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The 39th meeting of Protection Sub-Committee was held on 18.12.2019 at 10:00 Hrs at NRPC Secretarrat, New Delhi . The minutes of the meeting for the meeting is available on NRPC website and same can be downloaded from http://www.nrpc.gov.in .

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Members of Protection Sub-Committee (As per lisp

List of Members of PSC

Sl. No. Designation Organization Fax No. 1 Director (P&C) BBMB 0172-2652054

2 General Manager (SLDC) DTL 011-23236462

3 GM (O&M) Delhi Transco Limited 011-23236462

4 GM (T) Common Services IPGCL 011-23370247

5 Chief Engineer (TS) HVPNL 0172-2591244

6 SE (M&P) HVPNL 0172-2540014

7 SE (SO & SLDC) HVPNL 0172-2560622

8 SE (SLDC) PTCUL 0135-2763570

9 SE(T&C) PTCUL 0135-2451826

10 Chief Engineer (SLDC) UPPTCL 0522-2287880

11 SE(Tech) HPGCL 0172-5022436

12 SE(O&M-VI) HPGCL 0180-2566768

13 Chief Engineer (Transmission) HPSEB 01972-223435

14 SE (PR& ALDC) HPSEB 0177-2837143

15 Chief Engineer (Comml. & Survey Wing) PDD 0191-2474233

16 Chief Engineer (SLDC) PSTCL 0175-2365340

17 Chief Engineer (P&M) PSTCL 0161-2741280

18 CE (M&P) RRVPNL 0141-2291891

19 SE (Electrical) RRVUNL 01509-245299

20 Chief Engineer (LD) RRVPNL 0141-2740920

21 SE (SO&LD) RRVPNL 0141-2740920

22 Superintending Engineer (T&C) UPPCL 0121-2666062

23 Chief Engineer, (L-2) UPRVUNL 0522-2287822

24 DGM (T&C) PTCUL 0135-2760331

25 General Manager (O&M) NHPC 0129-2272413

26 GM (O&M) NR – I PGCIL 011-26601079

27 GM (O&M), NR-II PGCIL 01951-237186

28 Chief Manager (TS) N.R.L.D.C 011-26852747

29 GM(OS-NR) NTPC 0522-2305848

30 GM (OS) NTPC Ltd 0120-2410082

31 DGM (Maintenance) SJVNL 0177-2673283

32 DGM (O&M) THDC India Ltd 01376-236305

33 Director (GM division) CEA 011-26109750

34 General Manager APCLP 01251-266326

35 Director JPPVL 0120-4516201

36 Assistant Vice President BRPL 39996055

37 GM (Production) Jhajjar Power Ltd 01251-270155

38 GM(P&M) APL 7925557176

39 Sh. Umesh Gupta, AsVP BRPL 011-26419833

40 Director (NPC) CEA -

41

1.Maintenance Superintendent NAPS, NPCIL 05734-222167 2.Maintenance Superintendent RAPS, NPCIL 01475-242060

Minutes of 39th Protection Sub-Committee meeting (18th December, 2019)

Minutes of 39th Meeting of Protection Sub-committee

39th meeting of Protection Sub-Committee of NRPC was held on 18.12.2019 at NRPC Secretariat, New Delhi. The list of participants for the meeting is enclosed at Annexure–I.

A.1. Confirmation of minutes of 38th meeting of protection sub-committee

Minutes of 38th meeting of Protection Sub-committee were issued vide letter dated 09.10.2019. The Minutes are available on NRPC’s website at http://www.nrpc.gov.in. No comment has been received.

Sub-Committee confirmed the minutes.

A.2. Implementation of Recommendations of Task Force

As a follow up of one of the recommendations of Enquiry Committee headed by the Chairperson, CEA on grid disturbances that took place on 30th and 31st July 2012, Ministry of Power had constituted a ‘Task Force on Power System Analysis under Contingencies’ in December 2012. The Task Force had submitted its report in August 2013. In a meeting taken by Union Power Secretary on 11.03.2014, it was decided that the report be given wide circulation and its recommendations be implemented in a time bound manner. Some of the issues arising out of recommendations of the Task Force were as under:

A.2.1. Database of protection settings

Members were informed that protection setting database format is available at NRPC website and link for the same is available in the agenda. MS, NRPC informed members that as per the recommendation of Enquiry committee, data is to be provided by STU to concerned SLDC and CTU to NRLDC with a copy to NRPC. He stated that guidelines may be formulated for collection and regular updating of the protection setting database.

POWERGRID representative informed that protection setting data is collected at Regional level in POWERGRID and internal meetings are also conducted. He informed that protection settings are decided at Corporate level by all regions and same are shared at Regional level for implementation. He stated that protection setting data as extracted from the Relay is available at NTAMC, Manesar. He informed that there are two systems at Manesar i.e. RAS (Remote Accessibility System) & AFAS (Automatic Fault Analysis System) for substation connected from NTAMC, Manesar and DR can be extracted remotely for immediate analysis using these systems. However, protection setting updating need to be done only from OEM software of Relays and change in the setting of Relay are communicated to NTAMC for updating setting in AFAS. He also


highlighted that there were limitations of no. of clients from which relay can be connected.

It was decided that a visit to NTAMC, Manesar may be scheduled in the 1st week of January 2020 by a team of NRPC, NRLDC and POWERGRID to study the available infrastructure with POWERGRID to monitor and access protection relays remotely.

It was highlighted that implementation of such system may be difficult at Regional level. UP representative stated that it may be feasible at this stage to collate protection setting database in excel format.

Meanwhile, it was decided to start data collection in a phase manner by initially collecting protection setting data for 400 kV & above lines as well as ICTs of 400/220kV level. States and concerned transmission utilities were requested to submit 400kV & above data to NRPC Sectt. in the prescribed format (available at https://nrpc.gov.in/data-formats) by 10th January 2020.

It was also decided that a Nodal officer will be nominated from each utility/state who will co-ordinate for submitting new as well as updating the settings. Nomination of the nodal officer shall be submitted by 25th December 2019.

POWERGRID was requested to submit the protection setting data format for relay manufacturer other than already available in old format such as NR relays.

A.3. Final report of the Committee to suggest measures for bringing improvement in the field of Power System Protection among the utilities in Northern Region

Members were apprised that 2nd batch of 50 participants for each Level-2 and Level-3 Power System Protection training (classroom as well as hands-on) is being planned from 3rd week of January 2020 at PAL, Manesar as deliberated and approved in 44th TCC/47th NRPC meetings held on 10th /11th December 2019.

In the meeting, it was decided that TWO nominations from each utility/organization may be submitted to NRPC Sectt. (to email: [email protected]), latest by 30th December 2019. It was requested to all members to nominate those engineers who are working in the power system protection field for more than one year. Members deliberated that such trained participants may be kept in protection field only for better utilization of such training program.

It was also decided that entire training program will be organized in four batches (2 batches each for Level-2 and Levl-3 training) with sufficient time gap and Level–3 training will be conducted after completion of Level–2 training of two batches.

https://nrpc.gov.in/data-formats/

mailto:[email protected]


A.4. Persistent surge problem encountered by KWHEP since commissioning of Kala Amb substation (Agenda by KWHEP)

Members were informed that after the LILO of Kala Amb substation (about 175km from KWHEP), the problem of increase in LA counters had been witnessed at Karcham Wangtoo Pothead yard and the matter was deliberated in the last two PSC meeting. In the meeting, KWHEP representative informed that Karcham Wangtoo – Kala Amb line has been LILOed at 400 kV Wangtoo (HP) substation and line length of 400kV Karcham Wangtoo – Wangtoo (HP) substation is around 900 mtrs only. It was also informed that increase in LA counter has not been observed in recent 2-3 operations at 400kV Karcham Wangtoo. In view of the above, it was decided that this issue may be taken up in future meetings only if persistent surge problem is reported by Wangtoo (HP).

A.5. Oil leakage and High current/Overheating in Line reactor NGR (Agenda by NPCIL)

NPCIL representative informed that issue as highlighted in earlier meetings is still persisting and as decided in previous meeting, observations were recorded by taking Line shutdown RAPP-7&8 and Jaipur on 07.08.2019. The report regarding the flow of current in NGR was also submitted. Further, NPCIL representative gave brief presentation of the simulation studies carried out using PSCAD. He highlighted the result observations where zero sequence current was noticed in case of non-transposition of either RAPP-Kota or Kota-Jaipur lines. He requested that transposition details of 400kV Kota – Jaipur (S) line may be shared with NPCIL.

POWERGRID representative informed that R&D team of POWERGRID has been investigating and studying this issue. POWERGRID representative informed that such issues might have observed due to ferro-resonance and has been observed in cases where line is over compensated. He assured that complete details of 400kV Kota – Jaipur (S) line will be shared with NPCIL. He requested NPCIL that study report and PSCAD simulation model may be shared with POWERGRID for further studies.

NPCIL representative highlighted that operational modalities need to be finalized for 63 MVAr reactor at RAPP as well as 125 MVAr reactor at Jaipur (S). He stated that alternate operation of both reactors may be explored. In this regard, it was decided that agenda may be brought up by NPCIL in the forthcoming OCC meeting wherein interim measures may be deliberated until issue is resolved.

A.6. Follow up action on outstanding issues from previous meetings

A.6.1. Non-availability/defective PLCC link of STU Lines terminated at


POWERGRID (NR-2) substations

In the 38th PSC meeting held on 1st & 2nd August 2019, unavailability of PLCC for 220kV Verpal-I line at Amritsar S/s was discussed and PSTCL representative informed that end to end testing was pending.

The issue could not be deliberated in 39th Protection sub-committee meeting as there was no representation from PSTCL.

A.6.2. PLCC and Auto Re-closure issues related to UPPTCL

In the 28th PSC meeting held on 19.12.2014, POWERGRID informed that there were various lines of UPPTCL wherein PLCC panels and auto re-closure schemes were not in working condition due to which frequent tripping of lines on transient faults were taking place.

In the 39h PSC meeting, UPPTCL representative intimated that PLCC panel for 220kV Kanpur-Mainpuri line has been installed at Mainpuri end.

A.6.3. Islanding scheme for Rajasthan and Punjab

A.6.3.1. Islanding scheme for Rajasthan

In the 37th PSC meeting held on 21.01.2019, RVPNL representative informed that procurement was under process and expected to be completed by 30.06.2019. Subsequently, in the 38th PSC meeting held on 1st & 2nd August 2019, following status was updated by RVPNL:

UFRs for islanding scheme at 220kV S/s of Chittorgarh, Nimbahera, Sakatpura and Dahra commissioned

UFRs for islanding scheme at 220kV S/s of Baswara, Aspur and 132kV GSS Bagidora installed. Testing & commissioning to be done.

UFRs for islanding scheme at 220kV S/s of Debari and Madri – Relay received and installation under progress.

In the 39th Protection Sub-Committee meeting, matter could not be discussed as there was no representation from RVPNL.

A.6.3.2. Islanding scheme for Punjab

In the 38th PSC meeting held on 1st & 2nd August 2019, representative of Punjab informed that scheme has been installed and commissioned. In the meeting, PSTCL requested to conduct mock testing of the scheme and share the implemented scheme with NRPC/NRLDC.

The matter could not be deliberated in the 39th Protection sub-committee meeting as there was no representation from PSTCL.

A.6.4. Progress of rectification of deficiencies observed / improvements


suggested in Basic Protection Audit

The status of rectification of deficiencies observed in Basic Protection Audit carried out by POWERGRID & CPRI is enclosed as Annexure-II.

It was deliberated that there has been no representation from some utilities since last 3-4 Protection Sub-Committee meetings. It was decided that letter may be written to the head of these utilities regarding lack of representation in Protection sub-committee meetings.

A.6.5. Third-Party Protection Audit by the Protection Experts for intra-state system / balance system not covered in Basic Protection Audit.

In the 34th PSC meeting, stress was given over non-rectification of deficiencies found in the audit by most of the utilities. Utilities which have not submitted the action plan were requested to submit the same. Status of actions taken on Third Party Protection Audit is enclosed as Annexure-III.

All the utilities were again requested to submit the updated status and ensure expediting the process for rectification of discrepancies found in the audit.

A.6.6. Status of Bus Bar protection

The issue regarding non-availability/non-functionality of Bus Bar Protection has been deliberated in the past PSC meetings and utilities were regularly asked to take appropriate action on the findings of the report of Basic Protection Audit carried out by CPRI and POWERGRID in 2012.

The status of Bus bar protection for NR is enclosed as Annexure-IV.

All utilities were requested to update the status of Bus-bar protection and the status of interim measures taken at their end.

A.6.7. CERC order on Petition No. 9/SM/2014 and 10/SM/2014

Utilities were requested to submit the updated the status at the earliest. It was decided that NRPC Sectt. will again share the complete list of delayed clearance faults during April’14 to March’16 and utilities (except Central and East North Zone of UPPTCL, NJHPS, POWERGRID, NHPC, DTL and RRVPNL) shall submit the detailed report along with remedial measures taken/being taken by 1st January 2020.


A.7. Complete outage of Multi Terminal HVDC BNC-APD-Agra on 16th Sep 2019

POWERGRID representative presented the details of tripping which is enclosed as Annexure–V. It was informed that if there is fault between BNC-APD section, there will be 01 restart without Telecom after which complete tripping of link will take place. He stated that issue has also been discussed with OEM, consequently restart timing have been revised. He informed that DS which is like DC switch did not open at APD end and as there was Telecom failure only one restart attempt was taken after which complete link was tripped. The revised restart time will also allow larger time for fault clearances. In case of Telecom failure in healthy condition, there won’t be tripping of link.

Table Agenda: Formation of separate Post-Dispatch Analysis group at each SLDC/utility

Post-Dispatch Analysis is very important function for load dispatch centre/transmission licensee/generating stations. At RLDC front, such arrangement is working on following functions:

(i) Tripping Analysis

(ii) SoPR (Standard of Performance and Regulation) data for ISTS licensee

(iii) Frequent Single element tripping in a month

(iv) Multiple element tripping in a month

(v) Inter-Regional tripping in a month

(vi) FRC computation and analysis

(vii) Load Crash analysis

(viii) Reactive Power Management in its control area

(ix) LVRT/FRT issues or other protection related issues for renewable generators

(x) Protection database formation and updation

(xi) UFR and df/dt operation

(xii) ADMS (Automatic demand management system) related updates

(xiii) Analysis of sudden frequency excursions

(xiv) SPS operation and feedback

In line with RLDC, a dedicated Post-Dispatch Analysis group in state will help in coordinating with the site officials and prepare the detailed report for all


incidents and submit these reports to NRPC/NRLDC in a time frame stipulated in IEGC. UPPTCL representative in the 164th OCC meeting has cited improvement in its control area due to the formation of separate group to work on reliability issues. Other SLDC were also receptive to the idea of forming a separate Post-Dispatch Analysis group. 38th PSC and 164th OCC has agreed to the proposal and has advised for obtaining the approval of TCC/NRPC.

The issue was deliberated in 44th TCC/47th NRPC meeting, wherein TCC/NRPC gave its in-principle approval for the formation of the Post-Dispatch Analysis Group at each SLDC. It was decided that modalities for the group may be finalized in the upcoming PSC meeting.

In the 39th PSC meeting, it was deliberated that separate group for tripping analysis and other activities as mentioned above should be formed at each SLDC who may co-ordinate with STUs. BBMB representative informed that a group for tripping analysis has been formed. Utilities were requested that such group may be created at SLDCs at the earliest and details of the members in the group may be shared with NRPC/NRLDC.

A.8. Tripping events:

The complete summary of the events along with the information reported, action taken by entities is attached at Annexure-VI.

General Recommendation for NRPC-PSC meeting- NRPC suggested to all the utilities to prepare the presentation for all the tripping events for deliberation in PSC meeting. This procedure will be followed from next PSC meeting. Representative from the utilities shall collect all the information for its control area and share the details. At least one representative from each SLDC shall also be present during the meeting.

The recommendations of PSC are as follows:

A. Multiple Element tripping at 400/220kV Sultanpur (UP) Station at 22:55hrs of 09th Jun 2019 1. Distance protection setting of 400 kV Anpara (end)-Sultanpur ckt needs to

be reviewed and corrected. Changes in the setting to be shared with NRPC/ NRLDC. (Action: SLDC-UP, UPPTCL; Time: by 31.01.2020)

2. Timeframe for replacement of very old equipments in phased manner at 400 kV Sultanpur (UP) needs to be informed to NRPC/ NRLDC. (Action: SLDC-UP, UPPTCL; Time: by 31.01.2020)

3. DR time synch of all the 400 kV elements at 400 kV Sultanpur (UP) to be corrected. (Action: SLDC-UP, UPPTCL; Time: by 31.01.2020)

4. DR time synch of all the 400 kV elements at 400 kV Lucknow (PG) to be corrected. (Action: PG-NR3; Time: by 31.01.2020)


5. Availability of Analog and digital data of 400 kV Sultanpur (UP) needs to be ensured. (Action: SLDC-UP, UPPTCL; Time: by 31.01.2020)

6. Since, 400/220 kV ICT-3 didn’t trip due to wrong input of isolator auxiliary contact. Isolator auxiliary contact needs to be checked and recorded daily for healthiness of bus bar protection. It is a general recommendation already approved in PSC meeting and it needs to be strictly followed. (Action: General Recommendation)

7. CT having life more than 25 years should have monitored frequently with testing of CT parameters in every six months. (Action: General Recommendation)

8. Remedial action taken report needs to be shared by UPPTCL. (Action: SLDC-UP, UPPTCL; Time: by 31.01.2020)

B. Multiple element tripping at 400kV Alaknanda (UP) at 18:42hrs on 11-Jun-19

1. Since, Alaknanda HEP is in UP state control area. Therefore, UP SLDC

shall keep all the details w.r.t. tripping at Alaknanda HEP. All SLDCs to ensure that any information or detail in respect of any event concerning state control area generator to be available with by SLDC. (Action: All SLDCs)

2. Event couldn’t be discussed thoroughly due to insufficient information from the utilities. It was decided during the meeting that one team comprising of NRPC, NRLDC, POWERGRID, SLDC-UP and UPPTCL will do protection audit of 400 kV Alaknanda and Vishnuprayag in view of multiple times tripping in this area.

3. A report covering the following points w.r.t. the tripping to be shared (Action: SLDC-UP, UPPTCL; Time: by 31.01.2020):

a. Exact location of fault and nature of fault. b. Why 400kV Bus 1 at 400kV Alaknanda HEP(UP) tripped needs to

be looked into. c. Tripping of all tie CBs and main CBs connected to 400kV Bus1

shall be thoroughly checked in view of wrong wiring/operation of LBB/ Bus Bar Protection at 400 kV Alaknanda HEP.

d. Exact sequence of events in view of cause of event; protection operation/non-operation; opening, closing of breaker, isolator; relevant alarms and any other relevant detail to be shared.

e. 400 kV Bus Bar Protection/ LBB protection needs to be thoroughly checked at 400 kV Alaknanda HEP

f. Multiple protection related issues observed at 400 kV Alaknanda & Vishnuprayag station, Protection Audit needs to be done.

g. Detailed Report and Remedial measures report is still awaited from UPPTCL.


C. Complete Station outage of 400 kV Banda (UP) Station at 15:13hrs of 16th Jun 2019

1. Event couldn’t be discussed thoroughly due to insufficient information from

the utilities. It was decided during the meeting that UPPTCL shall internally review the protection setting of 400 kV Banda (UP) & Rewa Road station.


a. Sensitive distance zone protection setting at 400 kV Banda station needs to be checked and corrected.

b. Sensitive DEF protection setting in 400 kV Banda (end)-Rewa Road ckt-1 needs to be relooked.

c. Reason of tripping of 400kV Rewa Road (end)-Banda ckt-2 in Z-1 protection and over voltage protection also needs to be looked into.

d. Reverse zone protection setting in 400 kV Rewa Road (end)-Orai ckt-2 needs to be checked in view of reverse zone coverage upto transmission line from remote bus, single phase tripping & A/R in reverse zone.

e. Thorough protection setting review needs to be done at 400 kV Banda & Rewa Road ckts

f. Observation mentioned in UP report needs to relooked in view of aforesaid points.

g. Detailed report in NRPC approved format to be submitted considering the aforesaid points

D. Complete Station outage of 400 kV Hissar (PG) Station at 10:16hrs of 22nd Jun 2019

1. Event was discussed in details and it was concluded that till the time

POWERGRID explore any other option, transmission line shall be taken under emergency outage with taking code from RLDC in case of blocking of both M-I & M-II distance protection and line became unprotected. (Action: General Recommendation)

E. Multiple Element tripping at 400/220 kV Bareilly (UP) & 220kV Dhauliganga NHPC Station at 10:31hrs of 24th Jun 2019

1. Protection setting of 220 kV Dhauliganga HEP (end)- Bareilly (UP) & 220

kV Pithoragarh (end)-Bareilly (UP) needs to be checked in view of non-operation of distance protection in Z-2 & Z-3 time and share the report with NRPC/ NRLDC. (Action: SLDC-NHPC, POWERGRID & UPPTCL; Time: by 31.01.2020)

2. In 25th PSC meeting following was decided: Where Bus Bar Protection Scheme was currently not available, time setting of Bus coupler connected in between main Buses may be reduced to 100 msec. (operating time) and reverse reach of feeders may be reduced to 2 Km. and with time of operation as 160 msec. With above


settings, in case of actual Bus fault, Bus coupler operation will isolate the faulty Buses from other main Buses and feeders will also trip. This operation will reduce the fault duration and the healthy Buses will remain intact. PSC was of the view that scheme can be used purely as a temporary substitute till Bus Bar Protection is not installed. But at the same time, members expressed that endeavor should be made to operationalize Bus Bar Protection at the earliest. However, UPPTCL didn’t implement it at 400/220 kV Bareilly (UP). It shall be implemented till the time of outage of bus bar protection. (Action: SLDC-UP, UPPTCL; Time: by 31.01.2020) It was suggested to SLDC-UP and UPPTCL to check the compliance of decision occurred in PSC meeting.

3. Event couldn’t have concluded due to insufficient information from the utilities. It was decided during the meeting that UPPTCL shall conduct protection audit of 400/220 kV Bareilly (UP) in view of multiple times tripping at 400/220 kV Bareilly (UP). UPPTCL shall also share the protection audit report and consider the concerned raised in multiple elements tripping in last two years. (Action: SLDC-UP, UPPTCL; Time: by 31.01.2020)

4. A detailed report covering the following points w.r.t. the tripping to be shared (Action: SLDC-UP, UPPTCL; Time: by 31.01.2020):

a. Reason of non-tripping of 220 kV CB in newly commissioned bay of Bareilly UP (end)-CB Ganj2 ckt-2. Breaker operation testing report shall be submitted.

b. In flag details, over load tripping was mentioned for ICT-1 & 2, is it wrongly mentioned or actual tripping on over load protection?

c. Exact sequence of events in view of cause of event; protection operation/non-operation; opening, closing of breaker, isolator; relevant alarms and any other relevant detail to be shared.

d. Protection Audit at 400/220 kV Bareilly (UP) to be done. It was also proposed in earlier PSC meeting.

e. Reason of non-tripping of 220 kV Dhauliganga-Pithoragarh ckt & Dhauliganga-Bareilly UP ckt?

f. Detailed Report considering aforesaid points needs to be submitted from UPPTCL & NHPC.

F. Multiple element tripping at 400kV Alaknanda (UP) at 14:59hrs on 30-Jun-

19

1. Since, Alaknanda HEP is in UP state control area. Therefore, UP SLDC shall keep all the details w.r.t. tripping at Alaknanda HEP. All SLDCs to ensure that any information or detail in respect of any event concerning state control area generator to be available with by SLDC. (Action: All SLDCs)

2. Event couldn’t be discussed thoroughly due to insufficient information from the utilities. It was decided during the meeting that one team comprising of


NRPC, NRLDC, POWERGRID, SLDC-UP and UPPTCL will do protection audit of 400 kV Alaknanda and Vishnuprayag in view of multiple times tripping in this area.


a. Exact location of fault and nature of fault. b. Exact sequence of events in view of cause of event; protection

operation/non-operation; opening, closing of breaker, isolator; relevant alarms and any other relevant detail to be shared.

c. Why 400kV Bus 1 at 400kV Alaknanda HEP(UP) tripped needs to be looked into.

d. Tripping of all tie CBs and main CBs connected to 400kV Bus1 shall be thoroughly checked in view of wrong wiring/operation of LBB/ Bus Bar Protection at 400 kV Alaknanda HEP.

e. 400 kV Bus Bar Protection/ LBB protection needs to be thoroughly checked at 400 kV Alaknanda HEP

f. Multiple protection related issues observed at 400 kV Alaknanda & Vishnuprayag station, Protection Audit needs to be done.

g. Detailed Report and Remedial measures report is still awaited from UPPTCL

G. Multiple Element tripping at 400 kV Jodhpur (Raj) at 16:13hrs of 03rd July 2019

1. Event was not discussed due to no representation from RRVPNL & SLDC-

Rajasthan. 2. MS, NRPC suggested for DO letter to respective heads of the utilities

which are not present in the meeting like Rajasthan, Punjab,

Haryana, HP, Uttrakhand, J&K & SJVNL etc.

3. A report covering the following points w.r.t. the tripping to be shared (Action: Rajasthan; Time: by 31.01.2020):

a. Exact location and nature of fault? b. Operation of both the bus bar protection needs to be looked into. c. Complete station outage & delayed clearance of fault in case of

correct bus bar protection operation at 400 kV Jodhpur (Raj) needs to be looked into?

d. Healthiness of 400/220 kV bus bar protection at Jodhpur (Raj) needs to be checked and corrected.

e. Exact sequence of events in view of cause of event; protection operation/non-operation; opening, closing of breaker, isolator; relevant alarms and any other relevant detail to be shared.

f. Healthiness of station event logger at 400/220 kV Jodhpur (Raj) needs to be ensured.

g. Digital breaker status of 400 kV tripped elements & Analog data of outgoing line from 400 kV Jodhpur (Raj) needs to be checked and corrected.

h. Detailed Report and Remedial measures report is still awaited from Rajasthan.


H. Multiple Element tripping at 400 kV Akal (Raj) at 03:56hrs of 05th July

2019

1. Event was not discussed due to no representation from RRVPNL & SLDC-Rajasthan.

2. MS, NRPC suggested for DO letter to respective heads of the utilities



3. A report covering the following points w.r.t. the tripping to be shared (Action: Rajasthan; Time: by 31.01.2020):

a. Reason of delayed clearance of fault ? b. Healthiness of 220 kV bus bar protection/ LBB needs to be

checked. c. Exact sequence of events in view of cause of event; protection


d. Multiple 400 kV line tripping on over voltage protection needs to be looked into in view of CVT error, setting error and staggering in over voltage setting.

e. Non opening of 220 kV bus coupler at 400/220 kV Akal needs to be looked into.

f. Availability of SCADA digital data in Rajasthan/ NR SoE needs to be ensured.

g. It is suspected that cause of large renewable generation tripping is due to unavailability of FRT/ LVRT capabilities in various wind generating stations. These large scale tripping are serious threat for security of the entire grid and such type of incident also occurred in the past?

h. Detailed Report and Remedial measures report is still awaited from Rajasthan.

I. Multiple Element tripping at 400 kV Bawana DTL at 10:58hrs of 25th July 2019

1. Actions have already been taken by Delhi-STU. Further details will be

submitted in line with discussion points raised in PSC meeting. (Action: STU/SLDC-Delhi; Time: by 31.01.2020):

2. A detailed report covering the following pending points w.r.t. the tripping to be shared (Action: STU/SLDC-Delhi; Time: by 31.01.2020):

a. As reported 220 kV Bawana – Shalimar bagh Ckt-II tripped on R-N fault on distance protection. Reason of tripping of 220 kV Shalimar Bagh-Bawana ckt-2 within 250ms of fault occurrence.

b. Station Event logger details are still awaited from 400/220 kV Bawana CCGT. Healthiness of station event logger needs to be ensured.

c. Time synchronization of DR to be checked and corrected. J. Multiple Element tripping at 400/220 kV Wagoora (PG) at 17:43hrs of 26th

July 2019


1. Preventive maintenance for bus side equipment shall be properly taken

during bus shutdown to check if there is any physical damage in bus side equipment. (Action: General Recommendation)

2. Old Isolator auxiliary contact of all the 220 kV elements at 400/220 kV Wagoora (PG) shall be replaced. (Action: POWERGRID; Time Frame: 180-days)

3. NRPC suggested POWERGRID to share the complete scheme of backup impedance protection for ICTs and scheme would separately be discussed in next PSC meeting. In this regard, POWERGRID shall share the agenda. (Action: POWERGRID; Time Frame: next PSC meeting)

4. NRPC suggested for implementation of over current protection in the outgoing line from 400kV Uri-1 with OFC cable protection instead of tripping og GT on phase over current protection because with this arrangement we can survive Uri-1 units. NHPC representative agreed to look into the scheme and revert back in 15 days. (Action: NHPC; Time Frame: 15days)

K. Multiple Element tripping at 220 kV Khodri (Uttrakhand) at 11:42hrs of 09th Sep 2019

1. Event was not discussed due to no representation from PTCUL. 2. MS, NRPC suggested for DO letter to respective heads of the utilities



3. A report covering the following points w.r.t. the tripping to be shared (Action: PTCUL, Uttrakhand; Time: by 31.01.2020):

a. Exact location and nature of fault? b. Exact sequence of events in view of cause of event; protection

operation/non-operation; opening/closing of breaker, isolator; relevant alarms and any other relevant detail to be shared.

c. Reason of tripping of generation at 220 kV Chibro (Uttrakhand) needs to be looked into.

d. Reason of tripping of generation at 220 kV Khodri (Uttrakhand) needs to be looked into. Status of 220 kV Khodri-Saharanpur & 220 kV Khodri-Sarsawan during event needs to be checked and reported.

e. SCADA digital status for 220 kV Khodri (Uttrakhand) was not available in SoE.

f. In SCADA SLD of 220 kV Khodri (Uttrakhand), digital status of isolators/CB needs to be ensured for the better visibility of the system.

g. Detailed Report and Remedial measures report is still awaited from Uttrakhand.


L. Multiple Element tripping at 400/220kV Agra (UP) Station at 13:10hrs of 05th Oct 2019 1. In DMT (double main transfer breaker) scheme, Bus side isolator shall be

opened at the time of line taken under shutdown with both side earth switch under closed condition. Compliance needs to be done by all the NR utilities. (General Recommendation)

2. Healthiness of 400 kV bus bar protection needs to be ensured and till that time following shall be implemented as approved in earlier PSC meeting: (Action: SLDC-UP, UPPTCL; Time: by 31.01.2020) Where Bus Bar Protection Scheme was currently not available, time setting of Bus coupler connected in between main Buses may be reduced to 100 msec. (operating time) and reverse reach of feeders may be reduced to 2 Km. and with time of operation as 160 msec. With above settings, in case of actual Bus fault, Bus coupler operation will isolate the faulty Buses from other main Buses and feeders will also trip. This operation will reduce the fault duration and the healthy Buses will remain intact. PSC was of the view that scheme can be used purely as a temporary substitute till Bus Bar Protection is not installed. But at the same time, members expressed that endeavor should be made to operationalize Bus Bar Protection at the earliest.

3. Reason of tripping of 400 kV Agra-Unnao ckt and Agra-Fatehabad ckt-1 shall be checked, remedial action to be taken and findings to be shared. (Action: SLDC-UP, UPPTCL; Time: by 31.01.2020)

4. As informed during meeting, Station Event logger & automatic disturbance recorder at 400 kV Agra (UP) shall be corrected before Mar-2020. (Action: SLDC-UP, UPPTCL; Time: by 31.03.2020)

M. Multiple Element tripping at 400/220kV Sarnath (UP) Station at 17:54hrs

of 05th Oct 2019 1. 400 kV Bus Bar Protection at 400/220 kV Sarnath (UP) needs to be

reviewed and corrected. Changes in bus bar protection setting to be shared with NRPC/ NRLDC. (Action: SLDC-UP, UPPTCL; Time: by 31.01.2020)

2. Reason of tripping of 400 kV Anpara-Mau ckt during fault at Sarnath (UP) shall be checked, remedial action to be taken and findings to be shared. (Action: SLDC-UP, UPPTCL; Time: by 31.01.2020)

3. Time synch error of digital status (SCADA SoE) of tripped elements from 400 kV Sarnath (UP) needs to checked and corrected. (Action: SLDC-UP, UPPTCL; Time: by 31.01.2020)

4. As informed during meeting, Station Event logger at 400 kV Sarnath (UP) shall be corrected before Mar-2020. (Action: SLDC-UP, UPPTCL; Time: by 31.03.2020)


N. Multiple Element tripping at 400 kV Agra (PG) Station at 13:33hrs of 07th Oct 2019 1. Detailed description of changes in HVDC converter differential protection

setting in HVDC Agra-BNC to be shared with NRPC/ NRLDC. (Action: POWERGRID; Time: by 31.01.2020)

2. Reason of tripping of 765/400 kV ICT-1 & 2 at Agra (PG) shall be checked, remedial action to be taken and findings to be shared. (Action: POWERGRID; Time: by 31.01.2020)

O. Multiple Element tripping at 400 kV Banala (PG) at 18:29hrs of 21st Oct 2019

1. POWERGRID representative agreed to check the reason of sending of DT

from 400 kV Hamirpur to Banala (PG) and it further resulted unto tripping in the complex as only line available in the complex.

2. A report covering the following points w.r.t. the tripping to be shared (Action: POWERGRID-NR3; Time: by 31.01.2020):

a. Exact location and nature of fault? b. Non A/R of 400 kV Banala-Hamirpur ckt needs to be looked into. c. Preliminary Report, DR/EL details and detailed report are still

awaited from POWERGRID-NR3

P. Multiple Element tripping at 400kV Akal (Raj) Station at 11:16hrs of 01st

Nov 2019

1. Event couldn’t be discussed due to no representation from RRVPNL & Rajasthan SLDC.




3. A report covering the following points w.r.t. the tripping to be shared (Action: SLDC-Rajasthan, RRVPNL; Time: by 31.01.2020):

a. Reason of delayed clearance of fault? b. Healthiness of 220 kV bus bar protection/ LBB at 400/220 kV Akal

(Raj) needs to be checked. c. Non opening of 220 kV bus coupler at 400/220 kV Akal needs to be

looked into. d. Reason of tripping of 400/220 kV ICTs at Akal (Raj) from 220 kV

side as mentioned in flag details also needs to be checked in view of directionality of back up over current earth fault protection of ICTs.

e. 220 kV Akal (end)-Bhu ckt-1 & 2 and Akal (end)-Akal ckt-2 didn’t trip in reverse zone (Z-4) instead tripped in Z-1. Distance zone setting (Z-1 & Z-4) needs to be reviewed at 400/220 kV Akal (Raj)


f. All the DR received from Rajasthan have time synch error, sequence of event couldn’t be established because of time synch error. It needs to be addressed on priority.

g. Healthiness of station event logger at 400/220 kV Akal (Raj) also needs to be looked into.

h. Exact sequence of events in view of cause of event; protection operation/non-operation; opening, closing of breaker, isolator; relevant alarms and any other relevant detail to be shared.

i. Tripping didn’t capture in Rajasthan/ NR SoE. Availability of SCADA digital data in Rajasthan/ NR SoE needs to be ensured.

j. It is suspected that cause of large renewable generation tripping is due to unavailability of FRT/ LVRT capabilities in various wind generating stations. These large scale trippings are serious threat for security of the entire grid and such type of incident also occurred in the past?

k. Multiple times fault occurrence indicate the poor maintenance and protection system at 400/220 kV Akal (Raj). Third party Protection audit needs to be carried out at 400/220 kV Akal (Raj)

Q. Multiple Element tripping at 400kV Muzaffarnagar (UP) Station at

03:16hrs of 05th Nov 2019 1. Enabling of backup over current earth fault protection and its co-ordination

with line distance and ICT backup over current earth fault protection for bus coupler in DMT scheme will be discussed in next PSC meeting. All the utilities shall share their experience in this regard before next PSC meeting (Action: All the NR utilities; Time: before next PSC meeting)

2. Reason of tripping in Vishnuprayag, Alaknanda and Srinagar complex yet to be finalized. NRPC suggested UPPTCL to go through the pending points and a report covering the following points w.r.t. the tripping to be shared (Action: SLDC-UP, UPPTCL; Time: by 31.01.2020):

a. If 400 kV Muzaffarnagar-Vishnuprayag (end) ckt didn’t trip than how fault get clear in 1.5 second.

b. Reason of tripping of running units of Vishnu Prayag needs to be established as 400 kV Vishnuprayag-Alaknanda one ckt & 400 kV Alaknanda-Srinagar D/C was still connected after multiple element tripping at 400 kV Muzaffarnagar (UP). Vishnuprayag end data was stucked. Is there any island formation at 400 kV Vishnuprayag & Alaknanda units with Srinagar load? Details are still awaited

c. Time synch error and nomenclature issue captured through DR of Muzaffarnagar (UP) end. DR was also received only for 400 kV Muzaffarnagar-Ataur ckt.

d. Exact sequence of events in view of cause of event; protection operation/non-operation; opening, closing of breaker, isolator; relevant alarms and any other relevant detail to be shared.

e. Vishnuprayag end digital/analog data availability needs to be ensured.


f. Detailed Report and Remedial measures report is still awaited from UPPTCL.

R. Multiple Element tripping at 400 kV Jhakri HEP Station at 20:43hrs of 24th

Nov 2019

1. Event couldn’t be discussed due to no representation from SJVN (Jhakri & Rampur HEP).




3. A report covering the following points w.r.t. the tripping to be shared (Action: SJVN-Jhakri; Time: by 31.01.2020):

a. Reason of non-opening & failure of R-phase breaker of 400 kV Jhakri (end) breaker-Karcham ckt-2

b. Breaker over hauling report needs to be shared for 400 kV Jhakri (end) breaker-Karcham ckt-2

c. SCADA digital data status didn't capture for all the tripped elements. It needs to be looked into.

d. Station Event Logger output needs to be looked into and sequence of event (in ms) to be shared.

e. DT (direct trip) needs to be mapped in Rampur end DR of 400 kV Jhakri-Rampur ckt-2.

f. Detailed report and remedial measures report needs to be submitted considering the aforesaid points

S. Multiple Element tripping at 400 kV Uri II HEP Station at 09:07hrs of 27th

Nov 2019

1. NRPC suggested to NHPC for review the over current setting in 400 kV Uri-1 Uri-II ckt,

2. A report covering the following points w.r.t. the tripping to be shared (Action: NHPC; Time: by 31.01.2020):

a. Distance Z-1 protection setting of 400 kV Uri1 (end)-Uri2 ckt needs to be reviewed in view of distance over reach, tripping of two phases (Y&B-phase) instead of Y-phase & two phase tripping instead of all three phase

b. GPS time synch at 400 kV Uri-II will be once again checked in a month and than take further action.

c. GT neutral over current high set setting (1.02 PU with 500ms time delay) shall be reviewed, changes to be done and to be shared with NRPC/ NRLDC.

T. Multiple Element tripping at 220 kV Samaypur BBMB at 15:05hrs of 30th

Nov 2019 1. One to one testing for carrier communication in 220 kV Samaypur

(BBMB)-Faridabad (NTPC) shall be done and report to be shared within 7days. (Action: BBMB, NTPC; Time: 31.01.2020)


2. Reason of delayed opening of 220 kV Bus Coupler-2 at Samaypur (BBMB) needs to be looked into in view of actual delayed operation or SoE time synch error and remedial measures report to be submitted. (Action: BBMB; Time: 31.01.2020)

3. Online event log at dedicated PC shall be operationalised at 220 kV Samaypur (BBMB) in 6 months. (Action: BBMB; Time: 30.06.2020)

4. Time Synch GPS at 220 kV Samaypur (BBMB) shall be checked and corrected. (Action: BBMB; Time: 31.01.2020)

5. NRLDC representative further raised concern for unhealthy station event log at many of the 220 kV stations in Northern Region and requested to NRPC to take up it as a regular agenda from next meeting.

U. Complete Station Outage of 400 kV Dasna (UP) at 15:08hrs of 30th Nov 2019 1. 400 kV Bus Bar Protection operation for 400 kV Bus-2 needs to be

checked and reviewed in view of correct protection setting or any other issue as fault was in 400 kV bus-1 at 400/220 kV Dasna (UP). (Action: WUPPTCL; Time: 31.01.2020)

2. 400 kV Bus Bar Protection setting in view of permanent selection of Bus coupler CT needs to be discussed with OeM and share the feedback report with NRPC/ NRLDC (Action: WUPPTCL; Time: 31.01.2020)

3. Availability of digital and analog data of 400 kV Dasna (UP) needs to be ensured (Action: SLDC-UP, WUPPTCL; Time: by 31.01.2020)

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Annexure-II

Status of pending rectification of defects observed during BPA

Sl.No. Utility

No. of sub-stations covered under BPA

Expected Completion Remarks

1 UPPTCL 21 - Representative of UPPTCL informed that in 220 kV stations, PLCC panels were being procured from CGL and all major deficiencies have been rectified.

2 UPRVUNL 4 - Obra ’A’ – including rectification of time synchronization & BBP, PLCC (to be installed by UPPTCL). Harduaganj – to be updated by UPRVUNL.

Status could not be updated as there was no representation from UPRVUNL in the meetings.

3 HPSEB Ltd. 1 October 2017 Out of 12 deficiencies observed, 8 already rectified.

To be updated by HPSEB.

Status could not be updated as there was no representation from HPSEB.

4 UJVNL 1 December, 2016 Breaker for 220 kV Khodri-I &II needs to be replaced. Expected date as intimated by SLDC Uttarakhand in 127th OCC meeting was 31.12.2016. Status could not be updated as there was no representation from UJVNL in the meetings.

5 PDD, J&K 3 Status of progress is not submitted. Target completion not known.

As informed during 33rd NRPC meeting that deficiencies where procurement was not involved had been rectified and other works where procurement is involved are yet to be taken up. PDD J&K informed that they have submitted the proposal for PSDF funding and deficiencies will be rectified when fund will be disbursed from PSDF. As informed by PSTCL defects at 220kV Sarna-Udhampur line, pertains to PDD, J&K. Status could not be updated as there was no representation from PDD J&K in the meetings.

Annex-III

Protection audit of intra-state system/balance system not covered in Basic Protection Audit

Utility

Third party

protection audit

carried out by

No. of sub-stations covered/

expected to be covered

Status of Audit

Status of Report

Status of submission of

action Plan for rectification of

deficiencies

RRVPNL, RRVUNL

CPRI RRVPNL-39

RRVUNL-5

Completed Submitted RRVPNL- Lead Acid Batteries have been procured and installed.

RRVUNL- Action Plan submitted.

BBMB -do- 20 Completed Submitted The action to attend the deficiencies observed in the audit is underway.

PSTCL, PSPCL

-do- PSTCL-22

PSPCL-3

Completed Submitted Representative of PSTCL informed that Report on CPRI Audit submitted.

UPRVUNL -do- 2 Completed Submitted Parichha TPS and Panki TPS: Updated status to be submitted by UPRVUNL.

UPPTCL -do- 41 Completed Shall be submitted after receipt and examination of Report, same.

In 43rd TCC/46th NRPC meeting, UPPTCL informed 68 nos. 220kV substations work awarded to CPRI and work at 33 substations completed. Rest to be completed by January 2020.

Rosa Power -do- 1 Completed Submitted Action Plan submitted and the deficiencies observed rectified.

Utility

Third party

protection audit

carried out by



Status of Audit

Status of Report



deficiencies

UJVNL -do- 2

(Chilla, Chhibra)

Completed Submitted Action Plan not submitted.

No representative was present.

PDD J&K -do- 3

(Janipur, Amargarh, Hiranagar)

Completed Submitted Action Plan for Heeranagar and Amargarh not submitted.


JSW -do- 1 Completed Submitted Rectification of observation complied.

HPSEB Ltd.,

-do- 6

(Uprela Nangal, Giri 220 kV, Jassore 220 kV, Baddi, 220 kV Kangoo, 220 kV Kotla)

Completed Submitted Action Plan for 220 kV Kotla not yet submitted. Rectification of observation partly complied.


UT Chandigarh

-do- 1

(Kishengarh)

Completed Submitted Not submitted.


Budhil Power

-do- 1 Completed Submitted Not submitted.


HVPNL -do- 4 (Sector 72, Gurgaon ; Tepla;

Completed Submitted No representative was present.

Utility

Third party

protection audit

carried out by



Status of Audit

Status of Report



deficiencies

Bastara; A-5, Faridabad)

DTL -do- 4

(Rohini; Mehrauli; Mundka; Shalimar Bagh)

Completed Submitted Action has already been taken. Report will be submitted.

PTCUL -do- 4

(Pantnagar, Haridwar, Kashipur, Roorkee)

Completed Submitted Not submitted for Haridwar, Roorkee.


Annexure-IV

Status of Bus bar Protection for Northern Region Constituents

State/

Constituent

TRANSCO/ GENCO

Total no. of S/S/

Sw. yards

(220 kV and

above)

No. of S/S/ Sw. yards where Bus

bar protection is functioning

Remarks Action Plan

Delhi DTL 37 34

For 220 kV S/S namely, Gopalpur and Kanjhawala is being planned.(Lodi Road is GSS)

P.O. for 26 Nos. of substations has been awarded and out of which scheme at 05 Nos. of substations have been commissioned.

Haryana HVPNL 63 48

12 out of which 5 in process; 7 (date is yet to be decided); 3 not required.

Tentative date of commissioning was informed to be 30.06.2019.

No representative was present in 39th PSC.

Rajasthan RVPNL 53 46

(7 defective)

74 nos. new Bus bar Protection Scheme under commissioning. Work at 56 out of 74 locations completed.


Himachal Pradesh

HPSEB 08 04

At one S/s it was working. At 2 S/s, it was defective.

04 nos. commissioned and for remaining 04 s/s to be done by Oct 2017.


Punjab PSTCL 98 (5 no 400 kV

s/s)

46 (5 no. 400 kV s/s)

Work in progress for BBPS protection, 46/98 (220kV) 05/05 (400kV) completed. Till then reverse zone protection

time set to 160 ms. For remaining substations, work has been undertaken by TS organization and will be completed by 31.12.19. by TS organization. Procurement process for BBPS delayed due to re-tendering twice by Finance wing of PSTCL. Re-tendered again and target date is 31-12-19 & PSDF funding available. PLCC work will also be completed by 31-3-19 as procurement process is underway.


J&K PDD 06 -

The status for the same could not be ascertained as representative from PDD, J&K was not present in the meeting.

Uttarakhand PTCUL 10 09

Order placed for 01 defective. Would be completed by May 2017.


BBMB BBMB 23 20

Not required at Dhulkote and Jagadhari. also for Sangrur, Kurukshetra and Delhi as no. of feeders is less than five. PSC decided that it needs to be installed.

For Barnala it is to be provided by PSTCL as agreed in PSC. PSTCL were to commission it by 31.12.2016. BBP is being provided at Kurukshetra and Delhi substations. New Numerical Bus Bar Protection for both the substations has been received at site and likely to be

commissioned by 31.03.2020.

Uttar Pradesh UPPTCL 141 94

Representative of UPPTCL informed that SEL panels are being procured and its installation would be completed within 6 months.

1

Tripping analysis

of

16.09.2019 at 13:00:56 Hrs..

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Annexure - V

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Case Study – Tripping of NEA link On 16.09.2019

2

• Pole-1,2,3&4 at Agra& their complementary pole -1

& 2 at BNC & pole-3 & 4 at APD were running in

normal direction with a total of 1900 MW on NEA

link (500 MW from BNC to Agra and 1400MW from

APD to Agra).The Pole-1, 2, 3 &4 all at BNC, APD

and Agra end tripped on DC Line Fault between

BNC and APD. Power Flow after fault was zero.

.

Telecom & Restart Attempts In Multiterminal Philosophy

3

• Unlike Point to Point HVDC systems where restart

happens at (one and only) rectifier, in multi-terminal

HVDC systems simultaneous restarts happens at

each and every rectifier.

• Simultaneous restart by all rectifiers requires fast

coordination & signal exchange between them hence

making telecom and integral part of restart logic.


4

NEA HVDC Link has following restart logic

1) Fault Between AGRA & APD

a) With Telecom - 3 restarts followed by tripping of entire link

b) W/O telecom - 1 restart followed by tripping of entire link

2) Fault between BNC & APD

a) With Telecom – 1 restart followed by isolation of APD –BNC section

b) W/O Telecom - 1 restart followed by tripping of entire link


5


6

Restart With Telecom OK

7

Restart With Telecom not OK

8

Corrective Action taken

9

OEM(ABB AB ) suggested that every possibility must be

explored to clear the line fault section in the very first

restart attempt. Consequently restart timings were

revised as follows

Revised Previously

1st Restart – 300ms 200ms

2nd restart – 400ms 250ms

3rd restart -300ms 200ms

Revision Order of ABB RO -653 is attached herewith.

Performance of corrective action

10

Recently from 30th October onwards Stage DC line

faults were done at various locations on the entire NEA

HVDC link under low power flow testing for Line fault

locator calibration and it was observed that at all

points and on all incident restart of the link was

successful

THANKS

11

Annexure - VI

A. Multiple Element tripping at 400/220kV Sultanpur (UP) Station at 22:55hrs of 09th Jun 2019 Event category: GI-2 Generation loss (in MW): Nil Loss of load (in MW): Nil Energy load (in MU): Nil Data Summary received/available at NRLDC:

Description Fault Info Remarks

Fault Clearance Time 100ms & 100ms

As per PMU data

Phase of the fault

B-phase to earth fault followed by Y-phase and R-phase to earth fault

As per PMU data

Description Utilities

Present Status

Remarks

Availability of Digital Data (SCADA Data)

Partially Available

Time Synch error

DR/ EL Uttar Pradesh Received After 24hrs

POWERGRID Received After 24hrs

Preliminary Report Uttar Pradesh Received After 24hrs


Detailed Report Uttar Pradesh Received

Description Clauses Utility Remarks

Violation of Clauses

1. IEGC 5.2.r & 5.9.6.c (VI) 2. CEA (Technical standards for connectivity to the Grid) Regulation, 2007: Schedule Part 1. ( 6.1, 6.2) 3. 43.4.A & 43.4.D of CEA Technical Standard for

Uttar Pradesh

1. Preliminary Report, DR/EL after 24hrs 2. Detailed Report yet to be received 3. Adequately Sectionalized and graded protective relaying system 4. Incorrect/ mis-operation

Construction of Electrical Plants and Electric Lines; CEA (Technical standards for connectivity to the Grid) Regulation, 2007: Schedule Part 1. ( 6.1, 6.2, 6.3, 6.4) CEA (Technical standard for connectivity to the Grid, Amendment Regulation 2013), part-II, B2

/ unwanted operation of Protection system

Violation of Clauses 1. IEGC 5.2.r & 5.9.6.c (VI) 2. CEA grid Standard 15.3

POWERGRID 1. Preliminary Report, DR/EL after 24hrs

Based on above information description of the events is: 1. Connectivity diagram of 400/220 kV Sultanpur (UP):

2. At 400/220 kV Sultanpur (UP) station have double main transfer breaker scheme. It is connected through Tanda S/C, Lucknow (PG) S/C, and Anpara (via Obra) S/C. It also has two 315 MVA & one 240MVA 400/220 kV ICTs and one 80MVAr bus reactor.

3. In antecedent condition:

Name of Equipments Bus Position on 400KV Side

Load (Imp/Exp) in MW

315 MVA ICT-I A Bus 170 MW (Exp) 240 MVA ICT-II A Bus 122 MW (Exp) 315 MVA ICT-III A Bus 170 MW(Exp) 400KV Sultanpur-Lucknow (PG) line A Bus 38 MW (Imp)

400KV Sultanpur- NTPC Tanda line A Bus 67 MW (Exp)

400KV Sultanpur-Anpara (Obra) line B Bus 491 MW (Exp)

4. At 400kV Sultanpur (UP), 400kV Sultanpur – NTPC Tanda line (connected

on 400 kV bus-A) tripped due to bursting of 400kV Blue-phase CT at Sultanpur substation. Blue-phase CT also damaged Y-phase CT. It further resulted into operation of 400kV bus bar protection which tripped 400 kV Bus-A at Sultanpur (UP).

5. Anpara (Obra) line (connected on 400 kV Bus-B) tripped in zone-2 at Anpara end.

6. 400/220kV 315MVA ICT-III was also running through Bus-A during fault occurrence, but isolator contact status was not healthy at the moment therefore Bus bar protection relay didn’t sense 400/220kV 315MVA ICT-III

as connected to Bus A and didn’t issue tripping command for this ICT. 400 kV Bus-A at 400/220 kV Sultanpur (UP) was under charged condition as ICT-3 was connected through 220 kV side.

7. 400 kV Anpara-Lucknow (PG) ckt tripped on operation of bus bar protection, DT received at Lucknow (PG) end. 400/220 kV ICT-1 & 2 at Sultanpur (UP) also tripped on bus bar protection operation.

8. No load loss was reported. 220kV substation Sultanpur was unaffected. 9. Name of the tripped element:

400kV Sultanpur-Lucknow (PG) line 400kV Sultanpur-Tanda (NTPC) line 400/220kV 315MVA ICT-1 at Sultanpur (UP) 400/220kV 240MVA ICT-2 at Sultanpur (UP) 400kV Sultanpur (UP)-Obra(Anpara) line 80MVAR Bus reactor at 400/220 kV Sultanpur (UP) 400kV Bus Coupler at Sultanpur (UP)

10. PMU plots:

11. As per PMU data:

As per PMU, B-phase to earth fault followed by Y-phase to earth fault & R-phase to earth fault.

Fault Clearance time: 100ms

12. SCADA data and SoE: SoE captured for some of the tripped elements

13. As per Constituents details:

BBC make (Mfg 1984) 400kV CT installed on B phase of 400kV Sultanpur-NTPC Tanda (earlier Azamgarh) line got damaged at 400 kV s/s Sultanpur leading to single (B) phase tripping of line at Sultanpur end & 3 phase tripping of line at NTPC end. The line auto reclosed through M1 protection at Sultanpur end but due to additional damage of Y phase 400kV CT (BBC make Mfg 1984) relay sensed fault current in Y & B phase and issued tripping command on SOTF. Due bursting of CT Bus bar protection relay sensed fault in 400kV Bus A, thereby tripping Bus Coupler C.B. and all elements connected with 400 kV Bus- A.

400/220kV 315MVA ICT-III was also running through Bus-A during fault occurrence, but isolator contact status was not healthy at the moment therefore Bus bar protection relay didn’t sense 400/220kV 315MVA ICT-III as connected to Bus A and didn’t issue tripping command for this ICT.

400 kV Bus-A at 400/220 kV Sultanpur (UP) was under charged condition as ICT-3 was connected through 220 kV side.

400kV Sultanpur-Anpara line tripped from Anpara end in zone-2 sensing R-ph fault which is also clear from DR. Reason may unbalance current due to 80MVAR bus reactor at Sultanpur which functions as line reactor for charging this line from Anpara end, After opening of bus coupler this line was not feeding any load

14. Remedial Action taken and identified in UPPTCL report: Action taken: Current transformers of all three phases have been

replaced. Isolator contact status of ICT-3 has been set right Action to be taken: 400kv CTs at substation are very old.

Replacement is under consideration.

15. Preliminary Report and DR/EL details received after 24hrs but detailed report in desired format is still awaited from UPPTCL. Station EL detail is also not submitted.

Points for Discussion: 1. Bus Bar protection setting at 400 kV Sultanpur (UP) needs to be checked. 2. Is there actual bus bar fault or mal-operation of bus bar protection during

through fault condition? 3. Exact reason of tripping of 400 kV Anpara-Sultanpur (UP) ckt needs to be

looked into in view of fault clearance time was ~100ms in PMU data however line tripped after 500ms in Z-2. Distance Protection setting needs to be reviewed

4. Time synch error in various triggered DR needs to be corrected. 5. Analog and digital data (SCADA SoE) status to be checked and corrected. 6. Current status of pending remedial measures needs to be updated. 7. Detailed Report considering the aforesaid points needs to be submitted

Discussion during the meeting:

1. UP representative prepared presentation for the meeting and informed about the incident. Presentation is attached as Annexure-VI.a

2. 400 kV Anpara-Sultanpur (end) line charged through bus reactor bay. In 400 kV Sultanpur-Tanda line blue & yellow–phase CT bursted. All three phase of the line tripped from Tanda end however A/R from Sultanpur end

and finally tripped. 400 kV bus bar protection at Sultanpur (UP) also operated during damage in the CT.

3. 400 kV Anpara (end)-Sultanpur ckt tripped in Z-2, R-phase. Fault current of 1.5kA sensed in the DR, reason of the same yet to be concluded. There may be a chances of separate fault in the line at the same time.

4. As fault was in CT (dead tank CT) itself thatswhy many times bus bar protection operated due to adjacent location of bus bar protection core and distance protection core. Fault got clear after tripping of 400 kV Sultanpur (end)-Tanda ckt.

5. Remedial action already taken by UPPTCL: All the CTs (BBC make 1986 mfg) of 400kV Sultanpur-Tanda(NTPC) Line replaced at Sultanpur end. Bus Isolator contact status of ICT-III also set right. Vigilance has been increased for bus isolator auxiliary contact status to control room operator.

B. Multiple Element tripping at 400kV Alaknanda (UP) Station at 18:42hrs of 11th Jun 2019 Event category: GD-1 Generation loss (in MW): 310 MW Loss of load (in MW): Nil Energy load (in MU): Nil Data Summary received/available at NRLDC:

Description Reference Fault Info Remarks

Fault Clearance Time PMU data NA

Phase of the fault PMU data No fault in the system

Description Utilities Status Remarks


Uttar Pradesh Available

DR/EL Uttar Pradesh Not Received

Preliminary Report Uttar Pradesh Not Received

Detailed Report Uttar Pradesh Not Received



1. IEGC 5.2.r & 5.9.6.c (VI) 2. CEA (Technical standards for connectivity to the Grid) Regulation, 2007: Schedule Part 1. ( 6.1, 6.2) 3. 43.4.A & 43.4.D of CEA Technical Standard for Construction of Electrical Plants and Electric Lines; CEA (Technical standards for connectivity to the Grid) Regulation, 2007: Schedule Part 1. ( 6.1, 6.2, 6.3, 6.4) CEA (Technical standard for connectivity to the Grid, Amendment Regulation 2013), part-II, B2

Uttar Pradesh

1. Preliminary Report & DR/EL yet to be received 2. Detailed Report yet to be received 3. Adequately Sectionalized and graded protective relaying system 4. Incorrect/ mis-operation / unwanted operation of Protection system

Based on above information description of the events is:

1. Connectivity diagram of 400/220 kV Alaknanda (UP):

2. At 400 kV Alaknanda (UP) station have one an half breaker scheme. It is connected through Srinagar D/C, Vishnuprayag S/C and Muzaffarnagar S/C. It also have four units of 82.5MW each.

3. As reported 400 kV Alaknanda-Vishnuprayag ckt-2 & Alaknanda-Srinagar ckt-2 tripped due to DC mal function. At the same time 400 kV Bus-1 & all four running unit of 400 kV Alaknanda HEP also tripped.

4. Reason of multiple element tripping is still awaited. 5. In antecedent condition all the elements at 400 kV Alaknanda was in

service, all four units was running and generation was ~310MW. 6. Name of the tripped element:

400kV Alaknanda HEP(UP)-Srinagar(UTT) ckt-2 400kV Alaknanda HEP(UP)-Vishnuprayag ckt-2 400kV Bus 1 at 400kV Alaknanda HEP(UP) 82.5MW Unit#1 at 400kV Alaknanda HEP(UP) 82.5MW Unit#2 at 400kV Alaknanda HEP(UP) 82.5MW Unit#3 at 400kV Alaknanda HEP(UP) 82.5MW Unit#4 at 400kV Alaknanda HEP(UP)

7. PMU plots:

8. As per PMU & SCADA datadata: As per PMU, slight voltage dip observed in all three phase. Fault Clearance time: NA At 18:42:13,802hrs unit-1 at Alaknanda tripped and tie CB of unit-4 &

Muzaffarnagar ckt-2 tripped At 18:42:15,432hrs other connected elements main CB and tie CB

tripped except Srinagar ckt-1 & Muzaffarnagar ckt-2


10. Preliminary Report and DR/EL details and detailed report is still awaited from UPPTCL.

Points for Discussion: 1. Exact location of fault and nature of fault. 2. Why 400kV Bus 1 at 400kV Alaknanda HEP(UP) tripped needs to be

looked into. 3. Tripping of all tie CBs and main CBs connected to 400kV Bus1 shall be

thoroughly checked in view of wrong wiring/operation of LBB/ Bus Bar Protection at 400 kV Alaknanda HEP.

4. Exact sequence of events in view of cause of event; protection operation/non-operation; opening, closing of breaker, isolator; relevant alarms and any other relevant detail to be shared.

5. 400 kV Bus Bar Protection/ LBB protection needs to be thoroughly checked at 400 kV Alaknanda HEP

6. Multiple protection related issues observed at 400 kV Alaknanda & Vishnuprayag station, Protection Audit needs to be done.

7. Detailed Report and Remedial measures report is still awaited from UPPTCL

Discussion during meeting: 1. Tripping couldn’t have concluded due to lack of time synch data and

DR/EL data from Alaknanda. 2. Representative from Alaknanda informed that there was problem of DC

malfunctioning at 400 kV Alaknanda, DC changeover was being taken without taking outage of bus coupler. It further resulted into multiple element tripping due to extension of tripping command. Later on fault was also reported in 400 kV Alaknanda-Srinagar ckt-2.

3. Issue couldn’t have discussed thoroughly due to insufficient information from the utilities. It was decided during the meeting that one team comprising of NRPC, NRLDC, POWERGRID, SLDC-UP and UPPTCL will do protection audit of 400 kV Alaknanda and Vishnuprayag in view of multiple times tripping in this area.

4. Since, Alaknanda HEP is in UP state control area. Therefore, UP SLDC shall keep all the details w.r.t. tripping at Alaknanda HEP

C. Complete Station outage of 400 kV Banda (UP) Station at 15:13hrs of 16th Jun 2019 Event category: GI-2 Generation loss (in MW): Nil Loss of load (in MW): Nil Energy load (in MU): Nil Data Summary received/available at NRLDC:



As per PMU data

Phase of the fault

R-phase to earth, fault again occurred in breaker reclaim time of 25 second

As per PMU data

Description Utilities Present Status Remarks


Available









Uttar Pradesh

1. Preliminary Report, DR/EL after 24hrs 2. Detailed Report yet to be received 3. Adequately Sectionalized and graded protective relaying system 4. Incorrect/ mis-operation / unwanted operation of Protection system



Based on above information description of the events is: 1. Connectivity diagram of 400/220 kV Banda (UP):

2. At 400/220 kV Orai (UP) connected with Banda D/C, Mainpuri (765/400kV) D/C, Parichha D/C & Orai (PG) D/C.

3. R-phase to earth fault in 400 kV Orai (UP)-Orai (PG) ckt-2, line A/R successfully and finally tripped due to fault in breaker reclaim time.

4. At the time of fault in aforesaid line, 400 kV Rewa Road (end)-Banda ckt-1 tripped on DEF protection. (start attempt at the time of initial fault, tripping at the time of final tripping)

5. 400 kV Rewa Road (end)-Banda ckt-2 tripped in Z-1 protection (A/R successful at the time of first fault and finally tripped due to fault in breaker reclaim time)

6. 400 kV Banda-Orai (UP) ckt-2 also tripped in Z-4 protection (A/R successful at the time of first fault and finally tripped due to fault in breaker reclaim time).

7. Name of the tripped element: 400 kV Bus 1 at 400/220kV Banda(UP) 400kV Banda(UP)-Rewa Road(UP) ckt-1 400kV Banda(UP)-Rewa Road(UP) ckt-2 400kV Banda(UP)-Orai(UP) ckt-2 400kV Orai(UP)-Orai 765kV(PG) ckt-2

8. PMU plots:

9. As per PMU data: As per PMU, R-phase to earth fault, fault again occurred after 11.4

second (breaker reclaim time- 25 second). Fault Clearance time: 100ms


Time (in hrs) Ref. TimeRef. Time

(2nd time)

S/S

Name

Voltage

Level

(in kV)

Element

Name

Element

TypeStatus Remarks (From PMU & DR)

15:13:02,800Time Synch

error0ms

R-phase of 400 kV Orai (end)-Banda ckt-2

tripped in Z-4 (reverse zone)


error

R-phase Main CB of 400 kV Orai (end)-

Banda ckt-2 A/R


error

R-phase Tie CB of 400 kV Orai (end)-Banda

ckt-2 A/R


error11400ms

400 kV Orai (end)-Banda ckt-2 tripped in Z-

4 (All three phase)

15:13:10,560 0ms PMU Ref time

15:13:10,639 80ms ALHA1_U 400 05BANDA2Z-1 trip from 400 kV Rewa Road (end)-

Banda ckt-2

15:13:10,673 110ms ORAI1_U 400 22ORAPG2 R-phase of Orai (UP)-Orai PG ckt-2 tripped

15:13:10,678 120ms ORAI1_U 400 22ORAPG2 CB disturbe

15:13:10,678 120ms ORAI1_U 400 23SPORA2 CB disturbe

15:13:10,679 120ms ALHA1_U 400 05BANDA2 CB disturbe

15:13:10,689 130ms ORAI1_U 400 06BANDA2 CB disturbe

15:13:10,692 130ms ORAI1_U 400 05BNDFT2 CB disturbe

15:13:11,655 1100ms ALHA1_U 400 05BANDA2 A/R from Rewa Road end

15:13:11,667 1110ms ORAI1_U 400 22ORAPG2R-phase of Orai (UP)-Orai PG ckt-2 A/R

successfully

15:13:11,699 1140ms ORAI1_U 400 LIORAPG2Protection

TripDisp

15:13:11,732 1170ms ORAI1_U 400 22ORAPG2 CB Close

15:13:11,798 1240ms ALHA1_U 400 05BANDA2 CB Close

15:13:11,823 1260ms ORAI1_U 400 06BANDA2 CB Close

15:13:12,822 2260ms ORAI1_U 400 05BNDFT2 CB Open

15:13:12,949 2390ms ORAI1_U 400 23SPORA2 CB Close

15:13:13,446 2890ms ORAI1_U 400 05BNDFT2 CB Close

15:13:19,299 8740ms ORAI1_U 400 LIORAPG2Protection

TripApp

Time (in hrs) Ref. TimeRef. Time

(2nd time)

S/S

Name

Voltage

Level

(in kV)

Element

Name

Element

TypeStatus Remarks (From PMU & DR)

15:13:21,960 11400ms 0ms PMU Ref time

15:13:22,039 90ms ORAI1_U 400 22ORAPG2400kV Orai (UP)-Orai PG ckt-2 tripped

(distance Z-1)

15:13:22,048 90ms ALHA1_U 400 05BANDA2

Z-1 trip from 400 kV Rewa Road (end)-

Banda ckt-2 followed by fuse fail alarm

(Only R-phase open)

15:13:22,077 11520ms 120ms ORAI1_U 400 22ORAPG2 CB Open

15:13:22,081 11520ms 120ms ORAI1_U 400 23SPORA2 CB Open

15:13:22,091 11530ms 130ms ALHA1_U 400 05BANDA2 CB disturbe

15:13:22,098 11540ms 140ms ORAI1_U 400 06BANDA2 CB Open

15:13:22,102 11540ms 140ms ORAI1_U 400 05BNDFT2 CB Open

15:13:23,310 1450ms ALHA1_U 400 04BANDA1DEF trip at 400 kV Rewa Road (end)-Banda

ckt-1

15:13:23,330 12870ms 1470ms ALHA1_U 400 04BANDA1Protection

TripApp

15:13:23,354 12890ms 1490ms ALHA1_U 400 04BANDA1 CB Open

15:13:23,412 12950ms 1550ms BNDA1_U 400 417ALHT1 CB Open

15:13:23,414 12950ms 1550ms BNDA1_U 400 416ALHA1 CB Open

15:13:27,295 5440ms ALHA1_U 400 05BANDA2

Fuse Failure alarm persisted (distance

blocked) 400 kV Rewa Road (end)-Banda

ckt-2

15:13:27,520 5660ms ALHA1_U 400 05BANDA2Y & B-phase also tripped at 400 kV Rewa

Road (end)-Banda ckt-2

15:13:27,525 17070ms 5670ms ALHA1_U 400 05BANDA2 CB Open

15:13:27,536 5680ms ALHA1_U 400 05BANDA2 TOV stage-1 start

15:13:28,366 5810ms ALHA1_U 400 05BANDA2 DT send signal

15:13:28,381 5820ms ALHA1_U 400 05BANDA2Protection

TripApp

15:13:32,543 10680ms ALHA1_U 400 05BANDA2 TOV stage-1 trip

12. Remedial Action taken and identified in UPPTCL report:

13. Preliminary Report and DR/EL details received after 24hrs from UPPTCL. Detailed report is still awaited. Station EL detail is also not submitted.

Points for Discussion: 1. Sensitive distance zone protection setting at 400 kV Banda station needs

to be checked and corrected. 2. Sensitive DEF protection setting in 400 kV Banda (end)-Rewa Road ckt-1

needs to be relooked. 3. Reverse zone protection setting in 400 kV Rewa Road (end)-Orai ckt-2

needs to be checked in view of reverse zone coverage upto transmission line from remote bus, single phase tripping & A/R in reverse zone.

4. Thorough protection setting review needs to be done at 400 kV Banda & Rewa Road ckts

5. Observation mentioned in UP report needs to relooked in view of aforesaid points.

6. Detailed report in NRPC approved format to be submitted considering the aforesaid points

Discussion during the meeting: 1. Issue couldn’t have discussed thoroughly due to insufficient information

from the utilities. 2. UPPTCL representative agreed to review the protection setting of 400 kV

Banda (UP) & Rewa Road station. 3. NRLDC representative raised concern for submission of incomplete &

inconclusive information after six month of the incident and requested

SLDC-UP to intervene in the matter and take regular follow up to identify the root cause analysis.

4. UPPTCL representative didn’t prepare any presentation for the PSC meeting.

MS, NRPC raised serious concern against unpreparedness of UPPTCL.

D. Complete Station outage of 400 kV Hisar (PG) Station at 10:16hrs of 22nd Jun 2019 Event category: GD-1 Generation loss (in MW): Nil Loss of load (in MW): 600 (Haryana may confirm about load loss) Energy load (in MU): ___ (Haryana may confirm about load loss) Data Summary received/available at NRLDC:


Fault Clearance Time 1200ms As per PMU data

Phase of the fault

R-phase to earth fault followed by Y-phase to earth fault

As per PMU data



Available (Partial)

Time Synch error

DR/ EL POWERGRID Received After 24hrs

BBMB Not Received

Preliminary Report POWERGRID Received After 24hrs

BBMB Not Received

Detailed Report POWERGRID Not Received


Violation of Clauses 1. IEGC 5.2.r & 5.9.6.c (VI) 2. CEA (Technical standards


for connectivity to the Grid) Regulation, 2007: Schedule Part 1. ( 6.1, 6.2) 3. 43.4.A & 43.4.D of CEA Technical Standard for Construction of Electrical Plants and Electric Lines; CEA (Technical standards for connectivity to the Grid) Regulation, 2007: Schedule Part 1. ( 6.1, 6.2, 6.3, 6.4) CEA (Technical standard for connectivity to the Grid, Amendment Regulation 2013), part-II, B2

2. Detailed Report yet to be received 3. Incorrect/ mis-operation / unwanted operation of Protection system


BBMB 1. Preliminary Report, DR/EL after 24hrs

Based on above information description of the events is: 1. Single Line diagram of 400/220 kV Hissar (PG):

2. At 400/220 kV Hisar (PG) station have one and half breaker scheme. It is

connected through Moga triple ckts, Bhiwadi triple ckts, Kaithal D/C, Bhiwani (PG) D/C, Bhiwani (BBMB) S/C and Fatehabad (PG) S/C. It also have three 315 MVA 400/220 kV ICTs.

3. In antecedent condition, shutdown of 400 kV Kaithal-Hisar ckt-2 was applied for replacement of CVT.

4. At 10:16 Hrs, “R” Phase CVT of 400kV Hisar (PG)-Kaithal Ckt#2 failed at Hisar (PG) S/S. “R” & “Y” Phase CVT and Wave trap installed in “R” phase also damaged.

5. Both Distance Protections (ALSTOM make P-444/GE make D60) were already out of service due to fuse failure which resulted into tripling of all 400kV lines from remote end in Backup zone (Zone-2) and ICTs on Backup Impedance protection.

6. Blocking of primary distance protection on fuse failure resulted into delayed clearance of fault. Remote end of the all the outgoing lines tripped in Z-2 distance protection and ICTs tripped on back up impedance protection.

7. All the protection operated correctly with set time delay. 8. Name of the tripped element:

400 kV Hisar (PG)-Kaithal (PG) ckt-1,& 2 400 kV Hisar (PG)-Fatehabad (PG) ckt 400 kV Hisar (PG)-Bhiwani (BBMB) ckt 400 kV Hisar (PG)-Bhiwani (PG) ckt-1 & 2 400 kV Hisar (PG)-Moga (PG) ckt-1,2 & 3 400 kV Hisar (PG)-Bhiwadi (PG) ckt-1,2 & 3 400/220 kV 315 MVA ICT-1 , 2 & 3 at Hisar (PG)

9. PMU plots:

10. As per PMU data: As per PMU, R-phase to earth fault followed by Y-phase to earth fault. Fault Clearance time: 1200ms

a. SoE captured only for some of the tripped elements


12. As per Constituents details: Sequence of Event:

• At 10:16 Hrs on 22nd June,19, “R” Phase of 400kV Kaithal Ckt#2 CVT failed at Hisar Sub Station.

• Both Distance Protections (ALSTOM make P-444/GE make D60) were already out of service due to fuse failure which resulted into tripping of all 400kV lines from remote end in Backup zone and ICTs on Backup Impedance protection.

• “R” & “Y” Phase CVT and Wave trap installed in “R” phase also damaged. Fault Analysis: • At 01:54 Hrs and 02:32 Hrs “Fuse Fail” alarm was reported in D60 and

P444 relay of 400 kV Hisar(end)-Kaithal ckt-2 respectively. After thoroughly checking the secondary voltage circuit by 09:00 Hrs, it is concluded that “Fuse Fail” Alarm is due to “NO VOLTAGE OUTPUT” from CVT secondary circuit.

• Message was sent to CPCC/RTAMC for emergency shutdown of line from 11:00 Hrs to 15:00 hrs. All arrangement including Hydra crane was made and shifting of CVT from store to site is underway but at 10:16 Hrs the “R” Phase CVT blasted which lead to tripping of all element connected to Hisar 400kV Buses

Charging Sequence: • 400kV Bhiwadi-Hisar-1 - Charged at 21:40 Hrs on 22.06.19 • 400kV Bhiwadi-Hisar-2 - Charged at 13:25 Hrs on 22.06.19 • 400kV Bhiwadi-Hisar-3 - Charged at 13:37 Hrs on 22.06.19 • 400kV Kaithal-Hisar-1 - Charged at 12:52 Hrs on 22.06.19 • 400kV Kaithal-Hisar-2 - Charged at 17:32 Hrs on 23.06.19 (after

replacement of “R” & “Y” Phase CVT) • 400kV Hisar-Bhiwani(BBMB) - Charged at 12:07 Hrs on 22.06.19 • 400kV Bhiwani-Hisar-1 - Charged at 11:59 Hrs on 22.06.19 • 400kV Bhiwani-Hisar-2 - Charged at 11:22 Hrs on 22.06.19 • 400kV Bhiwani-Hisar-3 - Charged at 12:03 Hrs on 22.06.19 • 400kV Fatehabad-Hisar - Charged at 12:58 Hrs on 22.06.19 • 400/220kV ICT-1 - Charged at 13:02 Hrs on 22.06.19 • 400/220kV ICT-2 - Charged at 13:02 Hrs on 22.06.19 • 400/220kV ICT-3 - Charged at 13:24 Hrs on 22.06.19 • 400kV Moga-Hisar-1 - Charged at 11:35 Hrs on 22.06.19 • 400kV Moga-Hisar-1 - Charged at 11:33 Hrs on 22.06.19 • 400kV Moga-Hisar-1 - Charged at 11:37 Hrs on 22.06.19

13. Remedial Action taken and identified in POWERGRID report:

A modality is being finalized for necessary action in case of such extreme contingency of “Fuse Fail” alarm in both distance relay simultaneously in future

14. Preliminary Report and DR/EL details received within 24hrs from PG-NR2

and after 24hrs from PG-NR1.

Points for Discussion: 1. In case of blocking of distance protection what is the backup protection? 2. Following are some of the proposal for further discussion:

Taking line under shutdown whenever fuse failure block observed for both main protection of the line.

Automatic enabling of definite time non-directional backup over current protection with time delay of 250ms in case of blocking of distance protection on fuse failure.

Main-1 & Main-2 distance protection may take input from line CVT and Bus PT respectively.

3. Detailed Report and Remedial measures report is still awaited from

POWERGRID

Discussion during the meeting: 1. NRLDC representative informed about delayed clearance of fault and

tripping of all the elements either from remote end or backup over current/ earth fault protection. He further informed that there should be some provision in case of fuse failure in both M-1 & M-2 relay which resulted into blocking of distance protection.

2. POWERGRID representative informed that this incident was rarest of the rare condition, in which actual CVT fault occurred. In POWERGRID, SoP (Standard Procedure) was also not framed for such incident. This incident was discussed in details within POWERGRID and after discussion it was decided that in case of fuse failure in both main protection of the line, that line will be manually opened immediately.

3. NRLDC representative asked the house for any other option to cater such situation instead of opening of the line.

4. Rajasthan representative informed they have the practices to enables backup over current protection respectively in M-I & M-II protection, in case of blocking of distance protection due to fuse failure in respective relay.

5. POWERGRID representative informed that due to automatic enabling of backup over current protection there may be chances of cascade tripping of that 400 kV line during over loading.

6. NRLDC representative further suggested that if there is no other option than opening of line may be done with taking code from NRLDC by giving clear reason to the real time system operator. System operator can also differ the emergency shutdown in case system needs that line.

7. All the NR utilities agreed for the aforesaid point and ready to follow the procedure.

8. NRLDC representative requested with POWERGRID to further explore the possibility for any other option in case of fuse failure in both main protections.

E. Multiple Element tripping at 400/220 kV Bareilly (UP) & 220kV Dhauliganga NHPC Station at 10:31hrs of 24th Jun 2019 Event category: GD-1 Generation loss: 200 MW (As per UP report) Loss of load: 210 MW Energy load: 0.11 MU Data Summary received/available at NRLDC:



Phase of the fault

R-phase to earth fault followed by Y-phase to earth fault

As per PMU data


Present Status

Remarks


Available (Partial)

DR/ EL

Uttar Pradesh Received After 24hrs

NHPC Not Received



NHPC Received After 24hrs





1. IEGC 5.2.r & 5.9.6.c (VI) 2. CEA (Technical standards for connectivity to the Grid) Regulation, 2007: Schedule Part 1. ( 6.1, 6.2) 3. 43.4.A & 43.4.D of CEA Technical Standard for Construction of Electrical Plants and Electric Lines; CEA (Technical standards for connectivity to the Grid) Regulation, 2007: Schedule Part 1. ( 6.1, 6.2, 6.3, 6.4) CEA (Technical standard for connectivity to the Grid, Amendment Regulation 2013), part-II, B2 4. CEA GRid Standard 2010-3.e & CEA Transmission Planning Criteria

Uttar Pradesh & NHPC

1. Preliminary Report, DR/EL within 24hrs 2. Detailed Report yet to be received 3. Adequately Sectionalized and graded protective relaying system 4. Incorrect/ mis-operation / unwanted operation of Protection system 5. Delayed Clearance of fault



Based on above information description of the events is: 1. Single Line diagram of 400/220 kV Bareilly (UP):

2. At 400/220 kV Bareilly (UP) station have double main transfer breaker scheme. It is connected through Unnao D/C and Bareilly (PG) D/C. It also has three 315 MVA 400/220 kV ICTs. At 220 kV level, it is connected with 220 kV Dohna D/C, CB Ganj D/C, Pilibhit D/C, Pantnagar (PTCUL) S/C, Shahjahanpur (UP) S/C, Pithoragarh (PG) S/C & Dhauliganga S/C.

3. In antecedent condition:

• 220 kV Bareilly (UP)-CB Ganj 2 ckt-2 was charged under no load

condition from 220 kV Bareilly (UP). • One unit of 220 kV Dhauliganga HEP was under outage

4. In antecedent condition, 220 kV Bareilly (UP)-CB Ganj 2 ckt-2 was charged under no load condition from 220 kV Bareilly (UP). R-phase wave trap at 220 kV Bareilly (UP) (end)- CB Ganj 2 ckt-2 bursted, backup over current protection operated but breaker at 220 kV Bareilly (UP) end failed to open. It seems, LBB protection of that bay didn’t operate.

5. All 220 kV elements tripped from remote end in Z-2 & Z-3 protection. 220 kV Dhauliganga-Bareilly (UP) ckt tripped from Bareilly end on DT received from remote end.

6. 400/220 kV all three ICTs tripped in back up over current earth fault protection.

7. As per POWERGRID report, 220 kV Dhauliganga-Pithoragarh ckt tripped from Dhauliganga HEP.

8. As per NHPC report, both the lines tripped from remote end and units tripped on over speed

9. R-phase jumper of 220 kV Shahjahanpur-Bareilly ckt snapped and touched to Y-phase and then grounded. It resulted into R-Y double phase to earth fault in the system.

10. Breaker at Shahjahanpur end didn’t trip. LBB protection was also not in service and all the 220 kV lines tripped from remote end except 220 kV Shahjahanpur-Hardoi ckt.

11. 220 kV Shahjahanpur-Hardoi ckt tripped from Shahjahanpur end. 12. 200MVA 400/220 kV ICT-1 & 2 of Rosa TPS also tripped at the time of

fault in the system. 13. Unit-2 of Rosa TPS also tripped on earth fault protection. 14. Name of the tripped element:

220kV Shahjahanpur(UP)-Bareilly(UP) 220kV Shahjahanpur(UP)-Sitapur(UP) 220kV Shahjahanpur(UP)-Nighasan(UP) 220kV Shahjahanpur(UP)-Hardoi(UP) 220kV Rosa(UP)-Shahjahanpur(UP) ckt-1 220kV Rosa(UP)-Shahjahanpur(UP) ckt-2 200 MVA ICT 1 at 400/220kV Rosa(UP) 200 MVA ICT 2 at 400/220kV Rosa(UP) 300 MW Unit#2 at 400/220kV Rosa(UP)

15. PMU plots:

16. As per PMU data: As per PMU, R-phase to earth fault followed by Y-phase to earth fault.


17. SCADA data and SoE: Digital status captured in NR SoE is given below:

18. As per UPPTCL details:

19. Remedial Measures taken/ to be taken as per UPPTCL report:

Replacement process of damaged Wave Trap is under way. UPPTCL may kindly look into non tripping of main CB of 220 kV

Bareilly-CB Ganj ckt-2 Bay Thorough protection testing required at 400/220 kV Bareilly (UP)

20. As per NHPC details:

21. As per POWERGRID report:

22. Preliminary Report received from UPPTCL, DR/EL details received from PG-NR3. Detailed report still awaited from UPPTCL. DR/EL and detailed report awaited from NHPC

Points for Discussion: 1. Reason of non-tripping of 220 kV CB in newly commissioned bay of

Bareilly UP (end)-CB Ganj2 ckt-2. Breaker operation testing report shall be submitted.

2. In flag details, over load tripping was mentioned for ICT-1 & 2, is it wrongly mentioned or actual tripping on over load protection?


4. Protection Audit at 400/220 kV Bareilly (UP) to be done. It was also proposed in earlier PSC meeting.

5. Reason of tripping of 220 kV Dhauliganga-Pithrogarh ckt & Dhauliganga-Bareilly UP ckt?

6. Detailed Report considering aforesaid points needs to be submitted from UPPTCL & NHPC.


1. UP representative gave presentation during the meeting. Same is attached as Annexure-VI.b

2. UPPTCL representative informed that fault was in newly commissioned 220 kV Bareilly (UP)-CB Ganj ckt-2. This line was charged from Bareilly (UP) end. CT of this line was inadvertently shorted and it further resulted into non-operation of distance protection at 220 kV Bareilly (UP) end. All the 220 kV outgoing lines except 220 kV Dhauliganga and Pithoragarh ckt tripped from remote end of 220 kV Bareilly (UP). Wave trap of this line also damaged due to mounting problem in the line. Wave trap has been replaced.

3. Bus Bar Protection is ABB make RADSS and it was out of service. New bus bar protection is to be implemented.

4. NRLDC representative informed that in case of outage of bus bar protection it was already approved in NRPC that (Z-4) reverse zone distance protection setting shall be set at 160ms for all the lines and bus coupler over current earth fault setting shall be set with 100ms time delay to segregate the healthy bus from faulted bus.

5. NRLDC representative informed that there was delayed clearance of time than why distance zone protection didn’t sense the fault at 220 kV Dhauliganga HEP and Pithoragarh (PG).

6. Exact sequence of event couldn’t conclude due to non-availability of time synch data from

7. UP representative informed that 400/220 kV ICTs tripped on backup over current/ earth fault protection, over load was inadvertently mentioned in the report.

8. NRLDC representative raised concern about multiple times tripping at 400/220 kV Bareilly (UP) and also asked for compliance of earlier PSC decision of protection audit.

9. NRLDC representative once again requested for protection audit of 400/220 kV Bareilly (UP). He further requested for considering all the tripping related points raised in last two years. UPPTCL representative agreed for protection audit on or before 31st Jan 2020.

10. NHPC representative informed that 220 kV Dhauliganga-Bareilly (UP) didn’t trip, Dhauliganga generator tripped on over speed protection.

11. 220 kV Pithoragarh-Bareilly (UP) also didn’t trip from Pithoragarh end.

F. Multiple Element tripping at 400kV Alaknanda (UP) Station at 14:59hrs of

30th Jun 2019 Event category: GD-1 Generation loss (in MW): 340 MW Loss of load (in MW): Nil Energy load (in MU): Nil Data Summary received/available at NRLDC:


Fault Clearance Time PMU data 80ms

Phase of the fault PMU data Y-phase to earth fault



Uttar Pradesh Available

DR/EL Uttar Pradesh Not Received

Preliminary Report Uttar Pradesh Not Received





Uttar Pradesh



1. Single Line diagram of 400/220 kV Alaknanda (UP):

2. At 400 kV Alaknanda (UP) station have one an half breaker scheme. It is connected through Srinagar D/C, Vishnuprayag S/C and Muzaffarnagar S/C. It also have four units of 82.5MW each.

3. As reported Y-phase to earth fault occurred in 400 kV Alaknanda-Muzaffarnagar ckt-2, Muzaffarnagar (UP) end tripped.

4. After some time (1600ms), all other connected elements at 400 kV Alaknanda ckt tripped except 400 kV Srinagar ckt-1.

5. 400 kV Bus-A at Alaknanda HEP became dead. 400 kV Bus-B at Alaknanda HEP was charged through Srinagar ckt-1.

6. Reason of multiple element tripping is still awaited. 7. In antecedent condition all the elements at 400 kV Alaknanda was in

service, all four units were running and generation was ~340MW. 8. Name of the tripped element:

400kV Alaknanda HEP(UP)-Srinagar(UTT) ckt-2 400kV Alaknanda HEP(UP)-Vishnuprayag ckt-2 400kV Alaknanda HEP(UP)-Muzaffarnagar UP ckt-2 400kV Bus 1 at 400kV Alaknanda HEP(UP) 82.5MW Unit#1 at 400kV Alaknanda HEP(UP) 82.5MW Unit#2 at 400kV Alaknanda HEP(UP) 82.5MW Unit#3 at 400kV Alaknanda HEP(UP)

82.5MW Unit#4 at 400kV Alaknanda HEP(UP)

9. PMU plots:

10. As per PMU & SCADA data: As per PMU, voltage dip in Y-phase. Fault Clearance time: 80ms

11. SCADA data and SoE: SoE captured for all the tripped elements

12. Preliminary Report and DR/EL details and detailed report is still awaited from UPPTCL.

Points for Discussion:

1. Exact location of fault and nature of fault. 2. Exact sequence of events in view of cause of event; protection


3. Why 400kV Bus 1 at 400kV Alaknanda HEP(UP) tripped needs to be looked into.

4. Tripping of all tie CBs and main CBs connected to 400kV Bus1 shall be thoroughly checked in view of wrong wiring/operation of LBB/ Bus Bar Protection at 400 kV Alaknanda HEP.

5. 400 kV Bus Bar Protection/ LBB protection needs to be thoroughly checked at 400 kV Alaknanda HEP

6. Multiple protection related issues observed at 400 kV Alaknanda & Vishnuprayag station, Protection Audit needs to be done.

7. Detailed Report and Remedial measures report is still awaited from UPPTCL.

Aforesaid points will be taken care during protection audit of 400 kV

Alaknanda HEP.

G. Multiple Element tripping at 400kV Jodhpur (Raj) Station at 16:13hrs of 03rd Jul 2019 Event category: GI-2 Generation loss (in MW): Nil Loss of load (in MW): Nil Energy load (in MU): Nil Data Summary received/available at NRLDC:


Fault Clearance Time

PMU data 1400ms

Phase of the fault PMU data All three phase



Rajasthan Not Available

DR/EL Rajasthan Received (after 24hrs)

Preliminary Report Rajasthan Received (after 24hrs)

Detailed Report Rajasthan Not Received



1. IEGC 5.2.r & 5.9.6.c (VI) 2. CEA (Technical standards for connectivity to the Grid) Regulation, 2007: Schedule Part 1. ( 6.1, 6.2) 3. 43.4.A & 43.4.D of CEA Technical Standard for Construction of Electrical Plants and Electric Lines; CEA (Technical standards for connectivity to the Grid) Regulation, 2007: Schedule Part 1. ( 6.1, 6.2, 6.3, 6.4) CEA (Technical standard for connectivity to the Grid, Amendment Regulation 2013), part-II, B2 4. CEA Grid Standard 2010-3.e & CEA Transmission Planning Criteria

Rajasthan



1. Connectivity diagram of 400/220 kV Jodhpur (Raj):

2. At 400/220 kV Jodhpur (Raj) station have one and half breaker scheme. It is connected through Kankani D/C, Rajwest S/C, Kankroli S/C, Akal S/C & Bhadla (Raj) S/C. It also have two 315 MVA 400/220 kV ICTs.

3. Due to heavy storm and rain, Bus Post Insulator of 400 kV Bus-I broken and fall down on other live conductor. Bus bar protection of 400 kV Bus-I & II at 400/220kV Jodhpur(Raj) operated and all 400 kV lines and 400/220 kV ICT at Jodhpur (Raj) tripped. As per PMU, Voltage dip in all three phases is observed. In antecedent conditions, 315MVA ICT-I & II carrying 129MW & 125MW respectively

4. AT 400 KV GSS SURPURA-400 KV BUS 'A' DAMAGED due to heavy rain & Storm and bus bar protection scheme of BUS'A" operated. 400 kV Surpura-Kankraoli Line didn’t trip due to non operation of 296A relay of bus bar scheme of BUS A hence resulted in tripping of Kankani-II, Rajwest & Kankroli lines in zone-II. Both 315 MVA ILT transformers tripped on backup protection from 220 kV Side and inter tripped on 400 kV Side. The Akal line connected with Bus A tripped with operation of bus bar and sent DT to Akal end since Breaker B was already out of circuit.

5. Name of the tripped element at 03:57hrs: 400 KV Bus I & II 315 MVA ICT-I & II 400 kV Jodhpur- Kankani-I & II 400 kV Jodhpur-Kankroli 400 kV Jodhpur-Bhadla 400 kV Jodhpur-Akal 400 kV Jodhpur-Rajwest

6. PMU plots:

PMU Plot of frequency at Bassi(PG)16:13hrs/03-July-19

PMU Plot of phase voltage magnitude at Ratangarh(Raj)

16:13hrs/03-July-19

16:13:21.120hrs

16:13:21.240hrs 16:13:21.440hrs

16:13:22.560hrs

7. As per PMU & SCADA data:

As per PMU, Maximum dip in all three phase. Fault Clearance time: 1400ms

8. SCADA data and SoE: SoE didn’t capture for all the tripped elements

Rajasthan Demand pattern during tripping

Change in Demand of around 150MW(as per SCADA data).

9. As per Rajasthan details:

NAME OF LINETRIPPING

DATE

TRIPPING

TIME

CLOSING

DATE

CLOSING

TIMEINDICATION REMARKS

400/220kV, 315 MVA T/F

ALSTOM make

03/07/2019 16:12 Hrs 03/07/2019 19:40 Hrs Master Trip Relay 86A & 86B Optd Bus Bar A Operated

(Damaged)

400/220kV, 315 MVA T/F

BHEL make03/07/2019 16:12 Hrs 03/07/2019 20:36 Hrs Master Trip Relay 86A & 86B Optd

Bus Bar A Operated

(Damaged)

220 kV ILT Ist 03/07/2019 16:12 Hrs 03/07/2019 19:38 Hrs Master Trip Relay 86L OptdBus Bar A Operated

(Damaged)

220 kV ILT IInd 03/07/2019 16:12 Hrs 03/07/2019 20:37 Hrs Master Trip Relay 86L OptdBus Bar A Operated

(Damaged)

400 kV Ju-Kankani 1st 03/07/2019 16:12 Hrs Master Trip Relay 86A & 86B OptdBus Bar A Operated

(Damaged)

400 kV Ju-Kankani 2nd 03/07/2019 16:12 Hrs 03/07/2019 21:18 Hrs Master Trip Relay 186A & 186B OptdBus Bar A Operated

(Damaged)

400 kV Ju-Rajwest 03/07/2019 16:12 Hrs 03/07/2019 21:32 Hrs Master Trip Relay 186A & 186B Optd

Bus Bar A Operated

(Damaged)

400 kV Ju-Akal 03/07/2019 16:12 Hrs 03/07/2019 19:56 Hrs Master Trip Relay 186A & 186B OptdBus Bar A Operated

(Damaged)

400 kV Ju-Bhadla 03/07/2019 16:12 Hrs 03/07/2019 21:48 Hrs Master Trip Relay 186A & 186B OptdBus Bar A Operated

(Damaged)

400 kV Ju-Kankaroli 03/07/2019 16:20 Hrs 03/07/2019 20:23 Hrs Manually Tripped Manually tripped

220/132 kV 100MVA T/F 03/07/2019 16:12 Hrs 03/07/2019 20:58 Hrs Inter Trip-

132 kV I/C 03/07/2019 16:12 Hrs 03/07/2019 20:59 Hrs O/C ,E/F Relay (27 trip)-

10. NRLDC presentation including comment on data submission is attached as Annexure-VI.c

11. Preliminary Report received after 24hrs & DR/EL details received after 24hrs but detailed report and remedial measures report is still awaited from Rajasthan.

Points for Discussion: 1. Exact location and nature of fault? 2. Operation of both the bus bar protection needs to be looked into. 3. Complete station outage & delayed clearance of fault in case of correct

bus bar protection operation at 400 kV Jodhpur (Raj) needs to be looked into?

4. Healthiness of 400/220 kV bus bar protection at Jodhpur (Raj) needs to be checked and corrected.


6. Healthiness of station event logger at 400/220 kV Jodhpur (Raj) needs to be ensured.

7. Digital breaker status of 400 kV tripped elements & Analog data of outgoing line from 400 kV Jodhpur (Raj) needs to be checked and corrected.

8. Detailed Report and Remedial measures report is still awaited from Rajasthan.

No representative from Rajasthan RRVPNL, SLDC-Rajasthan & RRVUNL) was attended the meeting. SE, NRPC raised concern for non-submission of detailed report and no representation in the meeting.

H. Multiple Element tripping at 400kV Akal (Raj) Station at 03:56hrs of 05th Jul 2019 Event category: GD-1 Generation loss (in MW): 1735 MW (As per Rajasthan report) Loss of load (in MW): Nil (As per Rajasthan report) Energy load (in MU): Nil (As per Rajasthan report) Data Summary received/available at NRLDC:



PMU data 1600ms & 620ms

Phase of the fault PMU data R&Y-phase followed by B-phase





Preliminary Report Rajasthan Received (after 24hrs)





Rajasthan



1. Connectivity of 400/220 kV Akal (Raj):

Connectivity of 220 kV Akal (Raj)

BUS I

BUS II

220 KV

LALA

220 KV

MOOLAN

220 KV

BHU II

220 KV

BHU I

220 KV

RAJGARH

220 KV

BHENSADA

220 KV

AKAL I

220 KV

DANGARI I

220 KV

GIRALICT I

ICT III

220 KV

JAJIYA

220 KV

AKAL II

220 KV

DANGARI

220 KV

BARMER

220 KV B/C

220 KV Bus-I Jumper of C Phase of 220 KV Akal- Bhu Line-I Snapped & Ground 2. At 400/220 kV Akal (Raj) station have one and half breaker scheme at 400

kV side. It is connected through Kankani D/C, Ramgarh D/C, Barmer S/C

and Jodhpur S/C. It also have three 315 MVA 400/220 kV ICTs & one 500MVA 400/220 kV ICT.

3. 220 kV Akal is connected with 220 kV Akal2 D/C, Bhu D/C, Dangari D/C, Jajiya S/C, Moolan S/C, Lala S/C, Rajgarh S/C, Bhensada S/C & Giral S/C. All the lines are importing wind generation toward 400/220 kV Akal station except 220 kV Barmer, Giral and 400/220 kV ICTs

4. At 03:57hrs, Bus isolator jumper of 220 kV Akal-Bhu ckt-1 snapped and resulted into bus fault for 220 kV Akal station.

5. At the same time multiple 220 kV elements tripped at 400/220 kV Akal (Raj).

6. Multiple 400 kV outgoing lines also tripped on over voltage protection. 7. At 04:57 hrs, again bus fault occurred in the system and multiple 220 kV

lines and 400 kV lines at 400/220 kV Akal station tripped. 8. Name of the tripped element at 03:57hrs:

220 kV Akal-Bhu ckt-1 220 kV Akal-Bhu ckt-2 220 V Akal-Dangri ckt-1 220 kV Bus coupler at Akal station 400/220 kV 315 MVA ICT-2 & 3 at Akal (Raj) 400 kV Akal-Kankani ckt-1 400 kV Akal-Ramgarh ckt-2 400 kV Akal-Ramgarh ckt-2

9. Name of the tripped element at 04:57hrs:

400 kV Akal-Kankani ckt-2 400 kV Akal-Jodhpur ckt 400 kV Akal-Barmer ckt

10. PMU plots:


Dip in frequency of around 0.120Hz.

PMU Plot of phase voltage magnitude at Jodhpur(Raj)

03:56hrs/05-July-19

03:56:18.780hrs

03:56:18.860hrs

03:56:19.400hrs


PMU Plot of phase voltage magnitude at Jodhpur(Raj)

04:59hrs/05-July-19

04:59:29.400hrs

04:59:29.480hrs 04:59:31.000hrs

04:59:30.740hrs

11. As per PMU & SCADA data: As per PMU, Maximum dip in R&Y-phase followed by B-phase. Fault Clearance time: 1600ms & 620ms


Rajasthan Wind Generation pattern during tripping

Wind Generation loss of around 1500MW

(as per SCADA data).




S.

No.Name of Feeder

Tripping Time/

Date

Closing Time

& Date

Indication This

End

Indication

Other End Status Remarks

1.400 KV Akal-

Kakani Line-I

03:57

Hrs/05.07.19

06:59

Hrs/05.07.19Over voltage

Line charge

via NR

Code=313

220 KV Bus-I

Jumper of C

Phase of 220

KV Akal- Bhu

Line-I

Snapped &

Ground

2.400/220 KV ICT-II

315 MVA

03:57

Hrs/05.07.19

86 Relay &

NDR Operated Not Charge

3.400/220 KV ICT-II

315 MVA

03:57

Hrs/05.07.19

86 Relay &

NDR Operated Not Charge

4.220 KV Akal-Bhu

Line-II

03:57

Hrs/05.07.19

Dist optd, C

phase Zone-IIINot Charge

5220 KV Akal-

Dangri-I

03:57

Hrs/05.07.19Not Charge

6220 KV Bus

Coulper

03:57

Hrs/05.07.19

06:11

/05.07.19LBB optd Charge

S.

NO.

NAME OF

ELEMENT

TRIPPING

DATE

TRIPPING

TIME

CLOSIN

G DATE

CLOSING


1.400 KV Akal-

Kankani Line-I05.07.19 03:57 Hrs 05.07.19 6:59 Over voltage

220 KV Bus-I

Snapped Jumper

of C Phase of 220

KV Akal- Bhu Line-I

swing due to

heavy wind and

ground again at

4.57 Hrs

2.400/220 KV ICT-II

315 MVA 05.07.19 03:57 Hrs 05.07.19 9:07 86 Relay & NDR Operated

3.400/220 KV ICT-

III 315 MVA 05.07.19 03:57 Hrs 05.07.19 9:02 86 Relay & NDR Operated

4.220 KV Akal-Bhu

Line-II05.07.19 03:57 Hrs 05.07.19 8:36 Dist optd, C phase Zone-III

5220 KV Akal-

Dangri-I05.07.19 03:57 Hrs 05.07.19 9:38 Dist optd, RYB phase Dist, 47KM

6220 KV Bus

Coulper05.07.19 03:57 Hrs 05.07.19 6:11 LBB optd

7400 KV Akal-

Kankani Line-II05.07.19 03:57 Hrs 05.07.19 8:45 Over Voltage & D/T Rec

8400 KV Akal-

Jodhpur Line 05.07.19 03:57 Hrs 05.07.19 9:07 PSB Operated & D/T Rec.

9400KV Akal-

Barmer Line 05.07.19 03:57 Hrs 05.07.19 7:09 DT rec

10220 KV Akal-Lala

Line 05.07.19 03:57 Hrs 05.07.19 8:21 Zone-4,Dist optd C phase

S.

NoName of Feeder

Tripping Time/

Date

Closing Time

& Date

Indication

This End

Indication

Other End Status Remarks

1.400 KV Akal-

Kakani Line-II

04:57

Hrs/05.07.19

O/v oltage &

D/T Rec.Not Charge

220 KV Bus-I

Snapped

Jumper of C

Phase of 220

KV Akal- Bhu

Line-I swing

due to heavy

wind and

ground again

at 4.57 Hrs

2.400 kV Akal-

Jodhpur Line

04:57

Hrs/05.07.19

PSB

Operated &

D/T Rec.

Not Charge

3.400KV Akal-

Barmer Line

04:57

Hrs/05.07.19

7.09 Hrs

/05.07.2019DT rec Charged

4.220 KV Akal-Lala

Line

04:57

Hrs/05.07.19

Zone-4,Dist

optd C phaseNot Charge

14. Preliminary Report received after 24hrs & DR/EL details received after 24hrs but detailed report and remedial measures report is still awaited from Rajasthan.

Points for Discussion: 1. Reason of delayed clearance of fault ? 2. Healthiness of 220 kV bus bar protection/ LBB needs to be checked. 3. Exact sequence of events in view of cause of event; protection


4. Multiple 400 kV line tripping on over voltage protection needs to be looked into in view of CVT error, setting error and staggering in over voltage setting.

5. Non opening of 220 kV bus coupler at 400/220 kV Akal needs to be looked into.

6. Availability of SCADA digital data in Rajasthan/ NR SoE needs to be ensured.

7. It is suspected that cause of large renewable generation tripping is due to unavailability of FRT/ LVRT capabilities in various wind generating

stations. These large scale trippings are serious threat for security of the entire grid and such type of incident also occurred in the past?


No representative from Rajasthan 9RRVPNL, SLDC-Rajasthan & RRVUNL) was attended the meeting. SE, NRPC raised concern for non-submission of detailed report and no representation in the meeting.

I. Multiple Element tripping at 400 kV Bawana DTL at 10:58hrs of 25th July 2019 Event category: GD-1 Generation loss (in MW): Nil Loss of load (in MW): 326 (As per Delhi report) Energy load (in MU): 0.225 MU (As per Delhi report) Data Summary received/available at NRLDC:



Delhi Not Available

DR/EL Delhi Received (after 24hrs)

Preliminary Report Delhi Received (Within 24hrs)

Detailed Report Delhi Received




Delhi



1. Single Line diagram of 400 kV Bawana DTL:

2. 400 kV Bawana (DTL) station has one and half breaker scheme and double bus double breaker scheme. It is connected through Mandaula D/C, Mundka D/C, Abdullapur S/C, Dipalpur S/C and interconnector to Bawana CCGT. Bawana CCGT further connected with Bahadurgarh S/C, Bhiwani S/C and Dipalpur S/C. Bawana (DTL) and Bawana (CCGT) have total six 315 MVA 400/220 kV ICTs (2 at DTL and 4 at CCGT.

3. At 10:58 Hrs, Y-phase bus fault occurred at 220 kV Bus section-5 at Bawana CCGT, at the same time 400/220 kV ICT-1,4 & 5 tripped on backup over current earth fault protection, 220 kV Bawana-Shalimar Bagh ckt-2 tripped on differential protection.

4. 220 kV Bus Bar Protection was out of service due to some rectification work.

5. All the protection operated correctly with set time delay except 220 kV Bus Sectionaliser 3.

6. Preliminary Report received within 24hrs from DTL, DR/EL details received after 24hrs from DTL and detailed report also received.

7. Name of the tripped element: 315 MVA ICT –I 315 MVA ICT -IV 315 MVA ICT -V 220 kV Bawana- Shalimar bagh-I 220 kV Bawana- Shalimar bagh –II 220 kV Bawana-Rohini-I 220 kV Bawana-Rohini-II 220/66 KV 100 MVA Transformer - 1 at Bawana 220/33 KV 100 MVA Transformer – 3 at Shalimar bagh

8. PMU plots:

9. As per PMU & SCADA data: As per PMU, Y-phase to earth fault followed by R-phase to earth fault.

Fault Clearance time: 960ms SoE captured only for some of the tripped elements. 220 kV Shalimar Bagh-Bawana ckt-2 tripped within 240ms of fault

occurrence. 220kV side CB of 100MVA 220/33kV ICT at Shalimar bagh(DTL)

opens after 800ms of fault occurrence. CB of 220kV Bawana(DTL)-Shalimar bagh(DTL){end} ckt-1 opens

after 800ms of fault occurrence. 220kV side CB of 100MVA 220/66kV ICT at Bawana(DTL) opens after

800ms of fault occurrence


Tripping of 220 kV Bawana Shalimar Bagh (SMB) Ckt-2 occurred at 10.58.16.498 Hrs. Simultaneously with HV IDMT EF tripping ICT-1 & 5 trip occurred at 400 kV Bawana S/Stn. on date 25-07-2019 along with I/C-1 & 5. Apart from above 220 kV I/C-4 of 315 MVA ICT-4 also tripped on EF IDMT. Flash observed on terminal clamps of ICT-1 & 4 at LV BPI and Bushing clamps. Flash also observed by PPCL staff in 400 kV switchyard involving Bay 420 ICT-1, Bay 422 ICT-4 and Bay 424 ICT-5.

Both switch yard thoroughly checked and no visual arcing or no other flash sign was found.

DR for all aforesaid bays including transformer differential relay DR is attached for information and analysis along-with DR of 220 kV Bus Bar relay.

220 kV Bus Bar relay CT nomenclature in Bus Bar relay DR shown as F1, F2, F3........etc. In 220 kV Bus Bar relay DR is F1 means B/S-1, F2 means B/S-2, F3 means TBC-2, F4 means I/C-1, F5 means I/C-4, F6 means RHN2Ckt-2, F7 means RHN2 Ckt-1, F8 means SMB1, L1 means SMB-2, L2 means B/C-2, L3 means B/S-3, L4 means B/S-4 to be considered. DR of Bus Bar Section-2 relays revealed that 220 kV fault flow through Bus section-3 out of Bus-3 towards Bus-5.

As per DR analysis: Load on 220kV Bus-1, 3, 5 and 220kV Bus 2, 4, 6 was running separately with Bus Section-1, 2, 3, 4 in closed position and Bus Coupler-1, 2, 3 in OFF position. Fault occurred on Y phase of 200 kV Bus-5 which was fed by 315 MVA ICT-1, 4 (Magnitude 14.2 kA) through 220kV Bus Section-3 (Bay 224) towards Bus-5 approx. Apart from above 315 MVA ICT-5 fed the fault 6.12kA on 220 kV Bus-5 since connected directly to Bus-5. Total magnitude of fault was approx. 18.3kA from all three 315 MVA ICTs. Since the interconnection wiring work of 220 kV new Bus Bar with existing Bus-5 & 6 protection relay was in progress, so 220 kV Bus-5 relay didn’t detect the fault as was out of service due to Bus Bar interconnection work during that period. Thus fault cleared by OC+EF relays of 315 MVA ICT-1 & 5 and 220 KV I/C-4

12. Preliminary Report received within 24hrs & DR/EL details along with detailed report received after 24hrs from BBMB.

13. Preliminary Report, DR/EL and detailed report is still awaited from Haryana

Points for Discussion: 1. Exact location and reason of fault? 2. Exact sequence of events in view of cause of event; protection


3. Reason of non-tripping of 220 kV bus sectionaliser at 220 kV Bawana CCGT? Protection Coordination with 220 kV feeders to be ascertained

4. 220 kV Shalimar Bagh & Rohini-1 was radially fed from 400/220 kV Bawana CCGT or not ?

5. As reported 220 kV Bawana – Shalimar bagh Ckt-I tripped on R-N fault on distance protection. Reason of tripping of 220 kV Shalimar Bagh-Bawana ckt-2 within 250ms of fault occurrence?

6. 220 kV Bawana – Shalimar bagh Ckt-II tripped on differential protection from Shalimar bagh only. The same needs to be investigated and further details required.

7. Reason for tripping of 220/66 kV 100 MVA transformer – 1 at 220 kV Bawana station to be ascertained

8. Present status of bus bar protection at 400/220 kV Bawana CCGT 9. Why differential protection signal initiated in DR of ICTs and if initiated why

ICTs didn’t trip on differential protection? Time synch error of DR needs to be looked into.

10. Station Event logger details are still awaited from 400/220 kV Bawana CCGT

11. Shalimar bagh and Rohini (DTL) End DRs and Els: No DRs and Event loggers have been submitted.

12. Shalimar bagh and Rohini (DTL) End Observations: As reported 220 kV Bawana – Shalimar bagh Ckt-II tripped without any

indication from Shalimar bagh end same needs to be investigated. 220 kV Bawana – Shalimar bagh Ckt-I tripped on differential protection

from Shalimar bagh only. The same needs to be investigated and further details required.

Reason for tripping of 220/33 kV 100 MVA transformer – 3 at Shalimar bagh to be ascertained, whether O/C low set or high set operated.

Tripping indications/ reason for 220 kV Bawana – Rohini – I & II from Rohini end to be indicated

13. Detailed Report and Remedial measures report is still awaited from POWERGRID.


1. 220 kV Bawana station have total six 220 kV buses. Bus-1,2,3 & 4 was under outage for replacement of old static bus bar protection with new numerical bus bar protection. bus bar protection of bus-5&6 was also under outage.

2. Both lines of Shalimar Bagh and Rohini from Bawana were radially feed by Bawana end

3. Location of fault was on Y phase CT of 220kV IC-5 towards 220kV Bus-5 side. Reason of fault was flash between CT terminal towards earth. It further resulted into bus fault for 220 kV bus-5 at Bawana. Since the interconnection wiring work of 220kV new Bus Bar with existing Bus-5 & 6

protection relay was in progress, 220kV Bus-5 relay didn’t detect the fault as it was out of service.

4. Fault was cleared by O/C & E/F relays (IDMT E/F) of 315MVA ICT-1&5 and 220kV I/C-4.

5. 220kV Bawana Shalimar Bagh Ckt-2 tripped on Neutral differential feature (166 ms clearance time) from Bawana end which was set with trip delay of 80 ms to let instantaneous Phase differential feature. Since the fault was at adjacent section of Bawana 220kV Bus-5, this circuit tripping on external fault of line occurred due to unbalance of both end neutral highly sensitiveness of Neutral differential set at 10% pickup. This line tripped at both ends.

6. 220 kV Bawana-Shalimar Bagh ckt-2 was tripped due to sensitive backup over current earth fault protection (10%- 80A primary side). 220kV Bawana Shalimar Ckt-2 tripped on neutral differential at Bawana end which was set with trip delay 80ms thus final trip time 166mSec. Over current earth fault setting has been blocked and phase differential current setting has been revised from 20% (160A) to 10% (80A).

7. 220kV Bawana Shalimar Bagh-1 line tripped from Shalimar Bagh end only. This line was tripped on distance protection and the parallel circuit-2 was tripped on neutral differential after clearance 166ms, The flow of current was towards Bawana end which remained upto 800ms thus

tripping the line-1 on distance protection having No volt on Shalimar Bagh Bus. The fault was in reverse zone at Bawana end so Bawana end of Shalimar Bagh Ckt-1 did not trip. Zero Sequence filter will be added for proper operation of distance protection.

8. Reason of tripping of 220/66 kV 100 MVA transformer – 1 at 220 kV Bawana station & tripping of 220/33 kV 100 MVA transformer – 3 at Shalimar Bagh: Old Static over current protection don’t have features of zero sequence filtering so during voltage dip in the system in fault condition, circulating current flows in the transformer which further reflected as 3I0 current in neutral and resulted into tripping of transformer on over current earth fault condition. Similar condition arose for ICT at Shalimar Bagh & Bawana.

9. 220 kV Bawana – Rohini ckt– I & II didn’t trip, manually opened after complete station outage.

10. Why differential protection signal initiated in DR of ICTs and if initiated why ICTs didn’t trip on differential protection: Differential current was just above differential setting due to through fault on 220kV Bus-5. Differential picked up in ICT but did not tripped since differential pickup was set at 20% but tripping can occur only if bias slope condition is met. The fault of about 7000A requires more differential current at slope of 30%

11. Tripping Sequence: 220 kV Bus-5 Fault at Bawana, 220kV Bawana Shalimar-2 (166ms),

220kV IC-4 (732ms), 400kV ICT-1 (950ms), 400kV ICT-5(966ms), Shalimar Bagh end tripping 220kV Shalimar Bawana 1(800ms) 220kV Bawana Rohini-1&2, no tripping since no line volts

12. There was no protection philosophy in 220 kV bus sectionaliser at Bawana, no protection available in bus sectionaliser except LBB protection from Bus Bar initiation (96). Since 220 kV Bus Bar protection was out during Bus fault so no initiation was available for Bus Section LBB trip. Backup over current earth fault protection is available in bus coupler but not available in bus sectionaliser.

13. Erection, testing & commissioning of new numerical Bus-bar scheme at 400kV and 220kV voltage level has been completed at 400kV S/Stn Bawana.

J. Multiple Element tripping at 400/220 kV Wagoora (PG) at 17:43hrs of 26th July 2019 Event category: GD-1 Generation loss: 525 MW

Loss of load: 1000 MW Energy load: __ (Report from J&K is still pending) Data Summary received/available at NRLDC:



Phase of the fault

Y-N fault followed by R-N and B-N fault

As per PMU data


Present Status

Remarks


Received Time Synch error

DR/ EL



J&K Not Received After 24hrs

Preliminary Report



J&K Not Received After 24hrs

Detailed Report POWERGRID Not received



1. IEGC 5.2.r & 5.9.6.c (VI) 2. CEA (Technical standards for connectivity to the Grid) Regulation, 2007: Schedule Part 1. ( 6.1, 6.2) 3. 43.4.A & 43.4.D of CEA Technical Standard for Construction of Electrical Plants and Electric Lines; CEA (Technical standards for connectivity to the Grid) Regulation, 2007: Schedule Part 1. ( 6.1, 6.2,

POWERGRID, NHPC & J&K

1. DR/EL within 24hrs 2. Detailed Report yet to be received 3. Adequately Sectionalized and graded protective relaying system 4. Incorrect/ mis-operation / unwanted operation of Protection system 5. Delayed Clearance of fault

6.3, 6.4) CEA (Technical standard for connectivity to the Grid, Amendment Regulation 2013), part-II, B2 4. CEA GRid Standard 2010-3.e & CEA Transmission Planning Criteria


1. Single Line diagram of 400/220 kV Wagoora (PG):

2. 400/220 kV Wagoora (PG) station has DMT scheme at 400 kV & 220 kV side. It is connected through New Wanpoh D/C, Amargarh D/C and Uri-2 S/C. It also have four 315 MVA 400/220 kV ICTs. At 220 kV, Wagoora (PG) connected with Ziankote D/C, Kishanganga D/C (under charging stage) and Pampore D/C

3. In antecedent condition, all 400 and 220 kV lines and ICTs were in service with following load distribution on 220 kV side 315 MVA ICT-1 & 3 were connected to bus-1.

315 MVA ICT-2 & 4 were connected to bus-2. 220 kV Pampore -1 & Zainakot-1 were connected to bus -1 220 kV Pampore -2 & Zainakot-2 were connected to bus -2

4. In antecedent condition at 400 kV level: 400 kV New Wanpoh Wagoora I & II in service 400 kV New Wanpoh Kishenpur I, II, III and IV in service. Both ICTs and SVC in service

5. 220 kV Wagoora- Kishanganga D/C was to be charged from Wagoora end as an anti-theft measure. Two days back there was an incident of jumper cutting and the line route is full of ROW issues. As the lines were to be charged for the first time and keeping in view the other issues as above to avoid unwanted tripping occurrence, it was thought that the entire load would be shifted to 220 kV bus-2 and the new lines would be charged from 220 kV bus-1.

6. Load shifting was started and 220 kV Pampore-1 line was put on bus-2 by closing 20789B isolator and opening 20789A isolator. While shifting ICT-1 bay-209 to bus-2, 20989B isolator was closed and 20989A isolator (connected to bus-1) was opened. As it got opened its bus side jumper along with isolator arm snapped due to breaking of head of the BPI on which it was resting. This resulted in fault on 220 kV Wagoora (PG) bus-1.

7. 220 kV Bus bar protection did not operate as it was blocked due non-switching of CT after isolator operation.

8. BACKUP OVER CURRENT EARTH FAULT PROTECTION of 400/220 kV ICT-1 also didn’t operate due to faulty VT selection switching.

9. SVC at New Wanpoh tripped on over current earth fault protection of coupling transformer.

10. Name of the tripped element: 220KV Wagoora- Pampore- I 220KV Wagoora- Pampore- II 220KV Wagoora- Zainkote- I 220KV Wagoora- Zainkote- II 220 kV Bus-1 at Wagoora (PG) 220 kV Amargarh-Zainkote-I 220 kV Amargarh-Delina 220 kV Amargarh-Uri II 220 kV Zainkote-Delina ckt Unit-I of URI-I & Unit-1, II & III of URI-II Unit-I, II, III & IV of Kishanganga

11. PMU plots:

12. As per PMU data:

As per PMU, R-phase to earth fault followed by Y-phase to earth fault. Fault Clearance time: 1560ms

13. SCADA data and SoE:

14. As per POWERGRID details:

220 kV Wagoora- Kishanganga D/C was to be charged from Wagoora as an anti-theft measure. Two days back there was an incident of jumper cutting and the line route is full of ROW issues. As the lines were to be charged for the first time and keeping in view the other

issues as above to avoid unwanted tripping occurrence, it was thought that the entire load would be shifted to 220 kV bus-2 and the new lines would be charged from 220 kV bus-1.

Load shifting was started and 220 kV Pampore-1 line was put on bus-2 by closing 20789B isolator and opening 20789A isolator. While shifting ICT-1 bay-209 to bus-2, 20989B isolator was closed and 20989A isolator (connected to bus-1) was opened. As it got opened its bus side jumper along with isolator arm snapped due to breaking of head of the BPI on which it was resting. This resulted in fault on 220 kV Wagoora (PG) bus-1.

Bus bar protection did not operate as it was blocked due non-switching of CT after isolator operation.

Sequence of Operation: Bus-2 isolator (20789B) of 220 kV Pampore-1 line was closed at

17:37 hrs. Bus-1 isolator (20789A) of Pampore-1 line opened after closing

of B-isolator. Next, bus-2 isolator (20989B) of ICT-1 was closed at 17:40:25

hrs. Bus-1 isolator (20989A) of ICT-1 was opened at 17:43:33 hrs. Isolator auxiliary contacts did not switch correctly resulting in

improper CT switching. Bus bar protection went in block mode as CT switching has not taken place after 5 sec.

Bus-1 side jumper along with arm and terminal connector assembly of 20989A isolator of ICT-1 snapped due to breaking of head of the BPI on which it was resting.

This created bus fault on bus-1. Bus bar protection was in blocked condition hence did not operate

Sequence of operation Bus fault was created by breaking of isolator BPI at

17:43:38.628 hrs. 220 kV Pampore – 1 & 2 lines opened from Pampore end in

zone-2 17:43:40.269 and 17:43:38.718 hrs respectively. 220 kV Zainakote – 1 & 2 lines opened at Wagoora in reverse

zone at 17:43:39.164 and 17:43:39.182 hrs respectively. ICT-2 tripped on HV Over Current protection operation at

17:43:39.899 hrs. ICT-3 tripped on HV Over Current protection operation at

17:43:39.899 hrs. ICT-4 tripped on Backup Impedance protection operation at

17:43:39.160 hrs.

Bus coupler tripped at 17:43:46 hrs which cleared the fault Event Analysis:

220 kV Zainakote-1 and ICT-3 were feeding the fault directly as these were still connected to bus-1. 220 kV Pampore-1 & 2, ICT-1, 2 & 4 were feeding the fault through bus coupler as these elements were connected to bus-2.

Bus Bar protection was in blocked mode hence did not operate. Pampore lines tripped from JKPDD Pampore end. However, it

seems that Pampore-2 has over reached, the matter needs to be coordinated with PDD.

Zainakote lines tripped in reverse zone which is correct operation. However, these lines could have tripped from Zainakote end which needs to be coordinated with PDD end.

ICT-1 did not trip which is unacceptable. It would have tripped on BU OC protection. Voltage selection scheme was not working and voltage did not appear to BU OC & EF relay leading to its non-operation. Back up Impedance function was kept disabled in the new HV BU OC EF relay which was retrofitted in July’19.

ICT-2 tripped on HV BU OC & EF protection operation. Back Impedance function was kept disabled resulting in its non-operation of Back up IMP protection.


ICT-4 got isolated by operation of Back up Impedance which was enabled in HV OC EF relay. This was a desired operation.

Finally, fault get isolated by opening of Bus Coupler on its OC relay operation

It is found that protection configuration has some issues which need to

be resolved immediately. All the settings and functions shall be done as per recommendations

Due to auxiliary contact switching issues, isolator opening closing event did not capture in the events. Moreover some of the BCUs installed for remote operation also found out of time sync

At New Wanpoh: SVC at New Wanpoh tripped at 17:43:39.889 hrs on neutral

over current protection (50Z) operation for coupling transformer. The setting for this protection is 0.44 Amp and 1.2 Sec.

After the occurrence of fault, there was imbalance in system voltage. Y-ph voltage was reduced due to fault in that phase and same also reflected at New Wanpoh. SVC tried to correct this voltage drop, TSC had been put into service. But the voltage in B-ph rose to 260 kV which led to the outage of TSC due to high current. From the DR it can be seen that TSC has been switched in thrice as MVAr has risen thrice during the disturbance.

During this disturbance the neutral over current has gone above the set value of protection operation and persisted for 1.2 Sec which led to the tripping

Root Cause: Non operative Bus bar protection due to CT switching problem.

If the bus bar protection would have operated, nothing would have gone abnormal and cascaded tripping of other elements would have not occurred.

Unreliable isolator Auxiliary contact: Isolators are very old and auxiliary contact operation is unreliable.

Disabling of Backup IMP protection: Distance protection was kept disabled in HV BU OC EF relays since retrofitting resulting in non-operation of protection.

Non operation of Voltage selection scheme: VT selection relay of protection has not been selected, results in non-availability of VT at ICT 1 leading to OC E/F. The magnitude of the current had not gone to high set value and OC EF was the only protection to operate. The cause for VT selection problem is also attributed to auxiliary contact of isolators.

Any other information: The fault was fed through an arc developed between broken

isolator arm and pipe structure of that isolator. Also the jumper was swinging which resulted in variation and arc resistance, hence the fault current has not gone that high as in case of a dead bus fault. ICT-1 was feeding the fault for so long but the current was of magnitude of 2.3 kAmps and high set value of OC relay operation did not reach

Restoration time:

15. Remedial Measures taken/ to be taken as per POWERGRID report: Isolator mechanism boxes need to be replaced at the earliest – The

case is already under process for replacement of isolators. Protection functions/schemes shall be corrected as per

recommendations and approved drawings-- The settings and configuration has been corrected as desired.

Automation schemes such as VT selection, CT switching, Isolator interlocks etc. need to be made functional as possible till the replacement of Isolators.

Time synchronization of BCU need to be done--Under progress and will be completed by 20.08.19.

It was observed that crack had developed earlier in the broken BPI at the joint of porcelain and metallic portion. It has also been instructed to the stations to visually inspect for such things during bus shut downs so that mechanical failures like this may be avoided

16. As per NHPC details:

17. Preliminary Report received within 24hrs. DR/EL details & detailed report

received from POWERGRID but still awaited from NHPC and J&K.

Points for Discussion: 1. Manual error during shifting from 220 kV one bus to another bus at

Wagoora (PG)

2. Delayed clearance of fault 3. Non-operation/ Failure of 220 kV Bus Bar Protection at 400/220 kV

Wagoora (PG) 4. Non-operation of backup over current earth fault protection of ICT at

400/220 kV Wagoora (PG) needs to be looked into. 5. Reason of tripping of SVC at New Wanpoh during extreme contingency. 6. Reason of unit tripping at Uri-1 & Uri-2 HEP needs to be looked into. 7. Status of unit-3 tripping of Dulhasti HEP 8. Remedial measures taken and to be taken


1. POWERGRID representative gave presentation during the meeting, same is attached as Annexure-VI.d

2. Point wise reply given by POWERGRID: Manual error during shifting from 220 kV one bus to another bus at

Wagoora (PG): Instruction has been issued in this regard and one internal committee was also visited the site in view of seriousness of the event.

Delayed clearance of fault: Delayed clearance of fault was due to multiple failure of protection system like blocking of 220 kV bus bar protection due to non reporting isolator auxiliary contact status to bus bar protection during ICT-1 shifting, disabled backup impedance protection of ICT-1 and failure of backup earth fault protection on VT selection relay and outage of 220 kV bus bar protection at the time of fault.

Non-operation/ Failure of 220 kV Bus Bar Protection at 400/220 kV Wagoora (PG): Non operative Bus bar protection due to CT switching problem. If the bus bar protection would have operated, nothing would have gone abnormal and cascaded tripping of other elements would have not occurred. Isolators are very old and auxiliary contact operation is unreliable

Non-operation of backup over current earth fault protection of ICT-1 at 400/220 kV Wagoora (PG) needs to be looked into: VT selection relay of protection has not been selected, results in non-availability of VT at ICT 1 leading to OC E/F. The magnitude of the current had not gone to high set value and OC EF was the only protection to operate. The cause for VT selection problem is also attributed to auxiliary contact of isolators. Backup impedance protection was also not operated as distance protection was left disabled in HV BU OC EF relays since retrofitting resulting in non-operation of protection.

Reason of tripping of SVC at New Wanpoh during extreme contingency: After the occurrence of fault, there was imbalance in system voltage. Y-ph voltage was reduced due to fault in that phase and same also reflected at New Wanpoh. SVC tried to correct this voltage drop, TSC had been put into service. But the voltage in B-ph rose to 260 kV which led to the outage of TSC due to high current. From the DR it can be seen that TSC has been switched in thrice as MVAr has risen thrice during the disturbance. During this disturbance the neutral over current has gone above the set value of protection operation and persisted for 1.2 Sec which led to the tripping.

Reason of unit tripping at Uri-1 & Uri-2 HEP needs to be looked into. Status of unit-3 tripping of Dulhasti HEP Remedial measures taken and to be taken

3. Time sych issue was also identified during the incident and same has been rectified.

4. POWERGRID has issued internal circular that during bus maintenance isolator position and BPI shall be thoroughly checked apart from oiling and other activity.

5. POWERGRID representative further informed that they have replaced the backup over current earth fault protection with backup impedance protection at 90% of the location. Settings are given below:

a. Z1- 20% of the ICT impedance with instantaneous tripping b. Z2- 120% of the ICT impedance with 500-600ms time delay c. Z3- 100% of ICT impedance+100% impedance of the line with

maximum line length (Time delay of 1-1.2 second)

6. NHPC representative informed that 400 kV Dulhasti unit didn’t trip, there was some other problem that will be checked and reverted.

7. Uri-1 tripped on GT phase over current protection because there was OFC cable in both the ckts of 400 kV Uri-1 Amargarh and to protect the OFC able from leakage this GT phase over current protection was enabled. OFC cable has been replaced with XLPE cable in one ckt but for second ckt it is not in the pipeline. Before replacing both the cable it is not safe to disable the GT phase over current protection however NHPC agreed to relook this issue and consult with the OeM.

8. Uri-2 units were tripped due to tripping of GTs on backup over current earth fault protection.

9. Kishanganga units were tripped due complete outage of evacuation path. 10. NRPC suggested for implementation of over current protection in the

outgoing line from 400kV Uri-1 with OFC cable protection instead of

tripping GT on phase over current protection because with this arrangement we can survive Uri-1 units. NHPC representative agreed to look into the scheme and revert back in 15 days.

K. Multiple Element tripping at 220 kV Khodri (Uttrakhand) at 11:42hrs of 09th Sep 2019 Event category: GD-1 Generation loss (in MW): 290 MW Loss of load (in MW): 112 MW Energy load (in MU): Data Summary received/available at NRLDC:


Fault Clearance Time PMU data 100ms

Phase of the fault PMU data B-N fault



PTCUL Not Available

DR/EL PTCUL Not Received

Preliminary Report PTCUL Not Received

Detailed Report PTCUL Not Received



1. IEGC 5.2.r & 5.9.6.c (VI) 2. CEA (Technical standards for connectivity to the Grid) Regulation, 2007: Schedule Part 1. ( 6.1, 6.2) 3. 43.4.A & 43.4.D of CEA Technical Standard for Construction of Electrical Plants and Electric Lines; CEA (Technical standards for connectivity to the Grid) Regulation, 2007: Schedule Part 1. ( 6.1, 6.2, 6.3, 6.4) CEA (Technical standard for

PTCUL, Uttrakhand

1. Preliminary Report, DR/EL within 24hrs 2. Detailed Report yet to be received 3. Adequately Sectionalized and graded protective relaying system 4. Incorrect/ mis-operation / unwanted operation of Protection system

connectivity to the Grid, Amendment Regulation 2013), part-II, B2

Based on above information description of the events is: 1. Single Line diagram of 220 kV Khodri (PTCUL):

2. 220 kV Khodri station is connected with Chibro D/C, Rishikesh S/C, Majri S/C, Saharanpur S/C and Sarsawan S/C. It has double bus single breaker scheme and four running units of 30MW. (Chibro have four units of 60 MW)

3. Generation loss of about 300 MW in Uttarakhand occurs due to tripping of Chibro and Khodri Hydro plants after tripping of 220 kV Khodri(UK)-Majri(HP) line on B-N fault, FC-9.7 kA. Generation restored by 12.25 hrs. In HP, Load loss of 118 MW reported by SLDC. As per PMU, B-N fault with no auto-reclosing is observed. In antecedent conditions, Generation at 220kV Chibro(UTT) & 220kV Khodri(UTT) was 202MW & 89MW respectively. 220 KV Khodri(UTT)-Majri(HP) carrying 112MW.

4. Name of the tripped element: 220 kV Khodri (UTT) – Majri (HP) 60 MW Unit-1,2,3&4 at 220 kV Chibro (UTT) 30 MW Unit-1,2,3&4 at 220 kV Khodri (UTT)

5. PMU plots:

6. As per PMU & SCADA data: As per PMU, B-phase to earth fault. Fault Clearance time: 100ms

7. SCADA data and SoE: No SoE captured in NR SCADA

8. NRLDC observations:

As reported and as clear from PMU there was B-N fault in 220 kV Khodri – Majri line. The fault got cleared within 100ms.

Reason for tripping of 220 kV Sarsawan and Saharanpur lines may be made clear.

Reason for tripping of 220 kV Khodri – Chibro Ckt – I&II may be clarified.

Khodri Station Event logger not submitted. DRs for all the tripped elements may be submitted.

9. Preliminary Report, DR/EL details and detailed report is still awaited from

PTCUL


1. Exact location and nature of fault? 2. Exact sequence of events in view of cause of event; protection


3. Reason of tripping of generation at 220 kV Chibro (Uttrakhand) needs to be looked into.

4. Reason of tripping of generation at 220 kV Khodri (Uttrakhand) needs to be looked into. Status of 220 kV Khodri-Saharanpur & 220 kV Khodri-Sarsawan during event needs to be checked and reported

5. SCADA digital status for 220 kV Khodri (Uttrakhand) was not available in SoE.

6. In SCADA SLD of 220 kV Khodri (Uttrakhand), digital status of isolators/CB needs to be ensured for the better visibility of the system.

7. Detailed Report and Remedial measures report is still awaited from Uttrakhand.

Representative from Uttrakhand was not present during the meeting.

L. Multiple Element tripping at 400/220kV Agra (UP) Station at 13:10hrs of 05th Oct 2019 Event category: GD-1 Generation loss (in MW): Nil (As per UP report) Loss of load (in MW): 210 (As per UP report) Energy load (in MU): 0.63 Data Summary received/available at NRLDC:



Phase of the fault B-phase to earth fault

As per PMU data


Present Status

Remarks







Detailed Report Uttar Pradesh Not received




Uttar Pradesh

1. DR/EL within 24hrs 2. Detailed Report yet to be received 3. Adequately Sectionalized and graded protective relaying system 4. Incorrect/ mis-operation / unwanted operation of Protection system

Based on above information description of the events is: 1. SLD of 400/220 kV Agra (UP):

2. 400 kV Agra (UP) is connected with Fatehabad (UP) D/C, Agra (PG) S/C and Unnao S/C. It also have three 400/220 kV ICTs (2*500MVA+1*315MVA). 400 kV Agra (UP) has double main and transfer scheme

3. In antecedent condition: 220 kV Agra-Samsabad & 220 kV Agra UP-Agra2 UP ckt-1 & 2 was

under open condition. 500 MVA ICT-2 was also under outage. 400 kV Agra-Fatehabad ckt-2 was also under planned outage and both

end earth switch was closed. 400 kV Bus Bar Protection relay was not healthy so bus bar protection

was not in service.

4. At the time of charging of 765 kV Fatehabad-Lalitpur ckt-2 at13:00hrs, ckt-1 also tripped on over voltage protection from Fatehabad end.

5. 765 kV Fatehabad (end)-Lalitpur ckt-2 main breaker was charged for 10 minutes and finally tripped on line fault (Blue phase, Z-2) at 13:10hrs.

6. During fault in 765 kV Fatehabad-Lalitpur ckt-2, M-1 protection of 400 kV Agra (end)-Fatehabad ckt2 which was under S/D (earth switch of both end

was closed) was operated. As line was already under outage but fault persisted for Z-2 time, LBB protection operated and tripped 400 kV Bus-2 at 400/220 kV Agra (UP). It further resulted into tripping of 400 kV Agra (UP)-Agra (PG) & 500 MVA ICT-1

7. As per flag details it seems 400 kV Agra-Fatehabad ckt-1 tripped on over voltage stage-2 & 400 kV Agra-Unnao ckt tripped on over voltage stage-1.

8. Name of the tripped element: 400 kV Agra (UP) – Unnao (UP) 400 kV Agra (UP) – Fatehabad (765kV) Ckt - I 400 kV Agra (UP) – Agra (PG) 400 kV 500 MVA ICT-1 400 kV Bus Coupler 220 kV Agra-Mitai ckt 132 kV feeders tripped on SPS operation after tripping of 500MVA ICT-

1 at Agra (UP)

9. PMU plots:

10. As per PMU data: As per PMU, fault clearance time within 360ms. Fault was B-N fault.

11. SCADA data and SoE: SoE captured all the breaker of Sarnath (UP)

tripped before actual fault time (reference time from PMU data).

12. NRLDC observation: As reported while charging 765 kV Fatehabad-Lalitpur-II, 765 kV

Fatehabad-Lalitpur-I tripped from both ends. DT was sent to Lalitpur end from Fatehabad end. Overvoltage protection operated in 765 kV Fatehabad-Lalitpur-I where as it is evident from SCADA that Bus voltage was around 815 kV at time of tripping. OV settings needs to be checked.

At 13:10 hrs 765 kV Fatehabad-Lalitpur-II which was charged from Fatehabad end experienced B-N fault in Z-2. It seems that due to exceedingly high voltage at the floating end flash-over must have occurred over under passing 400 kV Agra(UP) – 765 kV Fatehabad (UP) Line.

As reported 400 kV Agra(UP) – 765 kV Fatehabad(UP) – II line was under shutdown with both end earth switched closed. Looking at the DR it is clear that inspite of CBs being open at Agra(UP) end distance protection relay registered current in 3 phases.

At 13:10 hrs 400 kV Agra(UP) – 765 kV Fatehabad (UP) Line relay operated in DEF thereby giving initiation to LBB. As current persisted for 200 ms LBB protection operated and tripped Bus bar – I.

DRs may be submitted in native comtrade format

13. As per Uttar Pradesh details:

14. Preliminary Report and DR/EL details received after 24hrs from UPPTCL. But detailed report yet to be received.

Points for Discussion: 1. Similar type of incident also occurred at 220 kV Meerut (PG). In DMT

(double main transfer breaker) scheme, Bus side isolator shall be opened at the time of line taken under shutdown with both side earth switch under closed condition.

2. Reason of tripping of 400 kV Agra-Unnao ckt & Agra-Fatehabad ckt on over voltage protection needs to be looked into.

3. Exact sequence of events in view of cause of event; protection operation/non-operation; opening/closing of breaker, isolator; relevant alarms and any other relevant detail to be shared.

4. Detailed report has been submitted by UPPTCL. Implementation status of remedial measures identified by UPPTCL

Discussion during the meeting: 1. UP representative informed that 400 kV Agra-Fatehabad ckt may have

tripped on over voltage protection during hanging 765 kV Fatehabad-Lalitpur ckt-2 from Fatehabad end from 13:00 hrs to 13:10 hrs.

2. UP representative further informed that 400 kV Agra-Unnao ckt was also tripped from Agra (UP) end on bus bar protection, it may be due to delayed opening of 400 kV bus coupler and extension of tripping command to other bus. 400 kV Agra-Unnao ckt tripped on over voltage protection from Unnao end as line was hanging from one end (Agra-UP end was already tripped).

3. NRLDC representative raised concern for non-tripping of 400 kV bus coupler, he informed that as per NRLDC SCADA SoE it seems bus coupler was open properly and in case of outage of bus bar protection relay, non-opening of bus coupler didn’t extend tripping command to other bus. It may be possible only in case of bus tied operation. Exact Sequence of event couldn’t finalize due to lack of time stamped information from UPPTCL.

4. UPPTCL agreed to further looked into the issue of tripping of 400 kV Agra-Unnao ckt and 400 kV Agra-Fatehabad ckt-1 on over voltage protection.

M. Multiple Element tripping at 400/220kV Sarnath (UP) Station at 17:54hrs of 05th Oct 2019 Event category: GD-1 Generation loss (in MW): Nil (As per UP report) Loss of load (in MW): 400 (As per UP report) Energy load (in MU):0.42 Data Summary received/available at NRLDC:



Phase of the fault R-phase to earth fault

As per PMU data


Present Status

Remarks







Detailed Report Uttar Pradesh Not received




Uttar Pradesh




Based on above information description of the events is: 1. Connectivity diagram of 400/220 kV Sarnath (UP):

2. 400/220 kV Sarnath (UP) has double main transfer bus scheme. 400 kV Sarnath (UP) is connected with Varanasi (PG) D/C, 400 kV Anpara (UP) D/C and Azamgarh S/C. It also has three ICTs, one of 400/220 kV 315MVA and two of 500 MVA.

3. In antecedent conditions all 400 kV elements connected at 400 kV Sarnath (UP).

4. R-phase CT of 400 kV Sarnath (end)-Varanasi ckt-1 bursted and resulted into 400 kV bus fault at 400 kV Sarnath (UP). During the incident all the connected elements from 400 kV Sarnath (UP) tripped simultaneously and further resulted into complete station outage. Operation of both 400 kV bus bar protection resulted into complete station outage of 400 kV Sarnath (UP).

5. Details of operation of both 400 kV bus bar protection needs to be looked into.

6. 400 kV Anpara-Mau ckt also tripped at the time bus fault. Reason yet to be ascertained.

7. Name of the tripped element: 400/220 kV 315MVA ICT-1 at Sarnath (UP) 400/220 kV 315MVA ICT-2 at Sarnath (UP) 400/220 kV 500MVA ICT at Sarnath (UP) 400 KV Sarnath-Azamgarh 400 KV Sarnath-Varanasi-I 400 KV Sarnath-Varanasi-II 400 KV Sarnath-Anpara L3 400 KV Sarnath-Anpara L5 400 kV Anpara-Mau ckt

8. PMU plots:

9. As per PMU data: As per PMU, fault clearance time within 100ms. Fault was R-N fault.

10. SCADA data and SoE: SoE captured all the breaker of Sarnath (UP)

tripped before actual fault time (reference time from PMU data).

11. As per Uttar Pradesh and POWERGRID details:

A.

B.

C .

Flag Details, DR and EL for each affected element: Fiag of 400 SNT- Varanasi (PG)-I Flag at other End

Main-I(Micom):- RYB phase Tripped ,

Zone-4, Diff. Optd, final tripping relay

R,Y,B Optd.

Main-II(ERL):- Zone-l, Auto reclose,

Optd, final tripping relay R,Y,B.

Name and Time of the Tripped elements in time Chronology: Based upon

time stamped event log, etc.

Event Data

Bus Bar Panel = R phase trip, Differential operated, Zone-l & Zone-ll operated.

Bus Bar annunciator pannel flags Trip relay-1, Optd.= Varanasi-l

All afected Feeders, Transformer, ICTs tripped at same time on 05.10.2019 at

17:54 hr.

400 KV Sarnath-Varanasi - l, R Phase CT Burst Location and type of fault :

Generation Loss / Load Loss :

Single Line Diagram (SLD) of affected Aea : Attached

Load Loss 400 MW

Trip relay-3, Optd =Anpara (L5)

Trip relay-2, optd = Varanasi-ll

Trip relay-5 operated = Bus Coupler.

Trip relay 6 operated = Tr Bus Coupler( 315 MVA ICT-I)

Trip relay-8, Optd = Anpara (L3) .

Trip relay 7 operated = 500 MVA ICT-ll.

Trip relay-9, operated = 400 KV Azamgarh .

Trip relay- 10 operated = 315 MVA ICT-lll .

Appropriate Graphical Plot: Including SCADA data / print out of DR and EL

details . It may be seperately annexed:

DR is attached.

Weather Information: Cloudy

Nil

___Change in Frequency :

Additional relevant information viz. power flow :

Detailed Analysis Report of Multiple Tripping at 400 KV S/S Sarnath Varanasi all Details 05.10.2019 at

17:54 Introduction

Time & Date of Event :

Substation (S) affected along with voltage level :

Brief Event Summary :

05.10.2019 at 17:54 hr

400 KV R Phase CT (Sarnath end) of 400 KV Sarnath- Varanasi -I Burst and resulted into 400 KV Bus fault and operation of both Bus bar protection

resulted into tripping of all the connected elements at Sarnath.

Electricity 400 KV Sub Station Sarnath, Varanasi.

Antecedent Conditions

Shutdowns etc :

D.

Element Type Rating Make Year of Manufacturing Year of Commissioning

1 CT (NPOULVZ) 400 KV TELK 1992 14.02.1995

E.

F.

G. Remedial Action

H. Lesson Learnt:

I. Any Other Information

Restoration ;- Restoration time of tripped elements in time Chronology

Remedial Action to be taken along with time frame.

S.

No.

Equipment failure (if any):

05.10.19 at 18:55

Name of the Element (along with voltage level)

Attached

400 KV Anpara L5 05.10.19 at 18:35

Event Description / Analysis of the Event Description : Detailed description including the reference of DR /EL and

explanation based on Event data.

Remedial Action Taken: With the help of thoroughly analysis of DR and relay setting it was found that Bus Coupler security

logic was based on SPS (Single Pole System) in place of DPS (Double Pole System)due to which in

last incident on 19.04.19 within 20 mili second Zone determination started and both Zone (Bus-I &

Bus-II) of Bus bar protection operated, to rectify such problem a delay of 1.5 Cycle (30 mili second)

is provided to start Zone determination after Bus Coupler Operation In Bus Coupler security logic

on 08.10.2019. .

While at that time(on incident of 19.04.19) OeM (SEL) was called and the report submitted by SEL

and no any rectification done /Solution given for such problem or nor addopted DPS in place of

SPS by SEL.

400 KV Varanasi-ll, Bus Coupler, 500 MVA ICT-ll 05.10.19 at 18:50

400 KV Varanasi-l 12.10.19 at 00:23 (After Successful Commissioning of New CT.)

315 MVA ICT-l. 05.10.19 at 19:11

400 KV Anpara L3 05.10.19 at 19:11

315 MVA ICT-III 05.10.19 at 18:52400 KV Azamgarh

As per POWERGRID report, Distance Protection (Main-I)/Micom P444

Relay seen the fault in zone-II at 17:54:08:165 ms and therefore start Zone-II as well as Zone-III.

Differential cum Distance Protection (Main-II)/Micom P546 Relay seen the fault in within zone 17:54:08:206 ms and therefore initial trip to faulty R-Phase. R-Phase CB Open at 252 ms and other Y&B Phase Open at 317 ms on DT RECEIVE


Action taken: With the help of thoroughly analysis of DR and relay setting it was found that Bus Coupler security logic was based on SPS (Single Pole System) in place of DPS (Double Pole System)due to which in last incident on 19.04.19 within 20 mili second Zone determination started and both Zone (Bus-I & Bus-II) of Bus bar protection operated, to rectify such problem a delay of 1.5 Cycle (30 mili second) is provided to start Zone determination after Bus Coupler Operation In Bus Coupler security logic on 08.10.2019.

Damaged CT of 400 kV Sarnath (end)-Varanasi ckt-1 was replaced at 00:23 hrs on dated 12.10.2019

Action to be taken: A thorough protection testing at 400 kV Sarnath (UP) S/S is required.

13. Preliminary Report and DR/EL details received after 24hrs from

POWERGRID. 14. Preliminary Report and DR/EL details received after 24hrs from UPPTCL.

But detailed report yet to be received.

Points for Discussion: 1. Reason of operation of both 400 kV bus bar protection at 400 kV Sarnath

(UP) to be checked and corrected. 2. 400 kV bus bar protection setting at Sarnath (UP) needs to be looked into. 3. Healthiness of bus bar protection at 400 kV Sarnath (UP) 4. Load loss and Energy loss during the incident 5. Tripping of 400 kV Anpara-Mau ckt during fault at Sarnath (UP) shall be

checked. 6. Time synchronization of digital SCADA SoE of Sarnath(UP) needs to be

looked into in view of time difference between PMU timing and SCADA SoE timing.

7. DR/EL and detailed report are still awaited from UPPTCL. 8. Remedial measures taken report along with detailed report considering

the aforesaid points to be submitted by UPPTCL. 9. DR/EL and Preliminary report needs to be submitted by POWERGRID. 10. Similar incident of operation of both bus bar protections at 400 kV Sarnath

(UP) (19th Apr 2019) was discussed during 38th PSC meeting and UPPTCL agreed to take action however it seems remedial measures didn’t take at Sarnath (UP).

Discussion during the meeting: 1. UP representative informed that 400 kV Sarnath (end)-Varanasi ckt-1 was

connected on 400 kV Bus-2, Sarnath end CT bursted and further resulted into bus bar protection of 400 kV bus-2 at Sarnath (UP). As per DR details, bus coupler was tripped first but current was showing till 30 second of bus coupler opening, during this 30 second, Z-1 (400 kV Bus-1) bus bar protection operated first followed by Z-2 (400 kV Bus-2) bus bar protection.

2. He further informed that 400 kV bus bar protection (SEL make) is healthy however operation of both bus bar protection was due to some logic issue in bus bar protection, issue has already been taken up with OeM. Remedial action like time delay of 30ms incorporated in bus bar protection to check the current across bus bar protection.

3. NRLDC representative informed that in DMT (double main transfer) scheme, main and check zone concept persisted for bus bar protection but here it seems bus bar protection as not taking input of check zone during operation. Representative from Western UP zone also supported the NRLDC view and informed that similar type of issue also held in 400 kV G. Noida and some changes was done in 400 kV bus bar protection. Minutes of meeting for mal operation at 400 kV G. Noida (UP) is as below:

N. Multiple Element tripping at 400 kV Agra (PG) Station at 13:33hrs of 07th Oct 2019 Event category: GI-2 Generation loss (in MW): Nil Loss of load (in MW): Nil Energy load (in MU): Nil Data Summary received/available at NRLDC:



Phase of the fault Y-phase to earth fault

As per PMU data


Present Status

Remarks



DR/ EL Uttar Pradesh Not Received After 24hrs


Preliminary Report Uttar Pradesh Not Received After 24hrs





1. IEGC 5.2.r & 5.9.6.c (VI) 2. CEA (Technical standards for connectivity to the Grid) Regulation, 2007: Schedule Part 1. ( 6.1, 6.2) 3. 43.4.A & 43.4.D of CEA Technical Standard for Construction of Electrical Plants and Electric Lines; CEA (Technical standards for connectivity to the Grid) Regulation, 2007: Schedule Part 1. ( 6.1, 6.2,

POWERGRID


6.3, 6.4) CEA (Technical standard for connectivity to the Grid, Amendment Regulation 2013), part-II, B2


Uttar Pradesh 1. Preliminary Report, DR/EL after 24hrs

Based on above information description of the events is: 1. SLD of 400/220 kV Agra (PG):

2. 400kV Agra(PG)-Agra(UP) tripped due to blast in Y-phase LA at Agra(PG) end. At the same time, 800kV HVDC Agra(PG)-BNC(PG) Pole-3 also tripped.

3. As per PMU, Y-N fault with unsuccessful auto reclosing is observed. In antecedent conditions, 1500MVA ICT 1 & 2 carrying 139MW & 137MW respectively, 400kV Agra(PG)-Agra(UP) carrying 175MW and 800kV HVDC Agra(PG)-BNC(PG) Pole-3 carrying 315MW.

4. As reported, HVDC Agra-BNC Pole-3 tripped on converter differential protection in 80ms of fault occurrence.

5. Name of the tripped element: 400 kV Agra (PG) – Agra (UP) 800 kV HVDC Agra (PG) – BNC (PG) Pole – 3 1500 MVA 765/400 kV ICT-1 & 2 at Agra (PG)

6. PMU plots:

7. As per PMU data: As per PMU, fault clearance time within 80ms. Fault was Y-N fault.

8. SCADA data and SoE:

9. As per POWERGRID details:

10. Preliminary Report, DR/EL and detailed report are still awaited from POWERGRID-NR3

Points for Discussion: 1. Exact location and nature of fault? 2. Exact sequence of events in view of cause of event; protection


3. From SoE data it seems that 1500MVA 765/400 kV ICTs at Agra (PG) also tripped. It needs to be looked into.

4. Why HVDC Agra-BNC pole-3 tripped on converter differential protection during AC line fault?

5. Preliminary Report, DR/EL details and detailed report are still awaited from POWERGRID-NR3

Discussion during the meeting: 1. POWERGRID representative gave presentation during the meeting. It is

attached as Annexure-VI.e 2. At 133312hrs on dated 07.10.2019, the Y-ph LA of 400kV Agra (PG)- Agra

(UPPCL) line failed at PG end. The distance protection on detection of a LG fault (FC: 41kA), attempted auto reclose after 01 second. However, the line subsequently tripped on persistent Yph to Earth fault (FC:52kA) and both Main & Tie CB of the line got opened at Agra end @133313hrs

3. At the first instant of Y-N fault in the line, North East Agra HVDC Pole -3 also tripped on converter differential protection @133312hrs. It was a mal-operation of DC CT of Pole-3. It may be due to CT saturation.

4. Reason of tripping of 765/400 kV ICT-1 & 2 will be checked and reverted. 5. Action taken for restoration of faulted line:

The failed LA was replaced by a new one The failure of LA had caused damage to nearby BPI, wave trap

support insulators also All such damages rectified/ replaced The line was taken back into service @0040hrs on 08.10.2019

6. Action taken for restoration of NEA Pole-3: The converter differential protection operated from only System A On clear identification of the issue with Zero flux DC CT measurement

by observing the events/TFRs of all other poles, the NEA pole-3 was taken back into service at 1408hrs.

7. Proactive action taken to avoid such mal-operation of NEA Pole-3: The Issue of wrong measurement of DC current by DC CT of Pole-3

System A was been taken up with OEM

Based on their findings new hardware and software revision has been done as per Revision order No. RO-646 (HITECC status connection need to change to avoid disturbance) in all the poles

8. NRLDC representative suggested that HVDCs are important link in system operation and mal-operation or non-operation of these high capacity HVDC may hamper the safe and secure grid operation. POWERGRID shall strongly take up these trippings with respective vendor for immediate improvement.

O. Multiple Element tripping at 400 kV Banala (PG) at 18:29hrs of 21st Oct 2019 Event category: GD-1 Generation loss (in MW): 500 MW Loss of load (in MW): Nil (Didn’t receive from HP) Energy load (in MU): __ (Didn’t receive from HP) Data Summary received/available at NRLDC:




As per PMU data


Present Status

Remarks


Received

DR/ EL POWERGRID Not received


Preliminary Report POWERGRID Not received






POWERGRID



NHPC 1. Preliminary Report, DR/EL after 24hrs

Based on above information description of the events is: 1. Connectivity Diagram of 400 kV Banala (PG):

2. 400kV Banala (PG) connected with Parbati-II S/C, Parbati-II S/C, Hamirpur (PG) S/C, Amritsar (PG) S/C, Nalagarh S/C & Koldam S/C. It has double bus single breaker scheme.

3. In antecedent condition: 400kV Banala(PG)-Hamirpur(PG) carrying 499MW & Parbati 3

HEP(NHPC) generating 352MW. 400 kV Banala-Amritsar (PG) & Banala-Koldam (NTPC) was under

planned outage (for installation of polymer insulator in place of disc) 400kV Banala-Nalagarh ckt was manually opened on high voltage

a. 4. Name of the tripped element:

400kV Banala(PG)-Hamirpur(PG) 400kV Banala(PG)-Parbati 3 HEP(NHPC) 400kV Parbati 3 HEP(NHPC)-Sainj HEP(HP) 400kV Parbati 2 HEP(NHPC)-Sainj HEP(HP) 130MW Unit#2, #3 at Parbati 3 HEP(NHPC) 50MW Unit#1, #2 at Sainj HEP(HP)

5. 400kV Banala(PG)-Hamirpur(PG) tripped on Y-N fault without any A/R in

the line. Due to loss of the only evacuation line (400kV Banala-Hamirpur line) all units of Parbati complex (Parbati-III, Parbati-II and Sainj HEP) tripped on over speed.

6. PMU plots:

PMU Plot of frequency at Bassi(PG)18:29hrs/21-Oct-19

Dip in frequency of around 0.049Hz

is observed.

PMU Plot of phase voltage magnitude at Jalandhar(PG)

18:29hrs/21-Oct-19

18:29:15:360hrs

18:29:15:440hrs

7. As per PMU data:

As per PMU, Y-phase to earth fault. Fault Clearance time: 100ms

8. SCADA data and SoE: SoE captured is tabulated below

NHPC/POWERGRID SCADA SOE

Time S/S NameVoltage Level (in

kV)

Element Name

Element Type Status Remarks

18:29:14:623 BANALA 400kV 07HMRPR1 Protection Trip App

18:29:14:654 BANALA 400kV 07HMRPR1 Circuit Breaker disturbe

18:29:14:726 BANALA 400kV 07HMRPR1 Protection Trip Disp

18:29:15:428 BANALA 400kV 07HMRPR1 Circuit Breaker OpenCB of 400kV Banala(PG){end}-Hamirpur(PG)

opens.

18:29:15:480 HAMIRPUR 400kV 03BNALA1 Circuit Breaker disturbe

18:29:15:560 HAMIRPUR 400kV 03BNALA1 Circuit Breaker OpenCB of 400kV Banala(PG)-Hamirpur(PG){end}

opens.

18:29:19:906 PARBATI3 400kV 01G1 Circuit Breaker OpenCB of 130MW Unit#1 at Parbati 3

HEP(NHPC) opens.


HEP(NHPC) opens.


HEP(NHPC) opens.

Parbati 3 HEP(NHPC) Generation pattern during tripping

Generation loss of around 370MW

(as per SCADA data).

9. As per NHPC report:

Extract of NHPC report (Parbati III)

Extract of NHPC report (Parbati II)

10. Preliminary Report, DR/EL and detailed report received from NHPC but still awaited from POWERGRID

Points for Discussion: 1. Exact location and nature of fault? 2. Non A/R of 400 kV Banala-Hamirpur ckt needs to be looked into. 3. Preliminary Report, DR/EL details and detailed report are still awaited

from POWERGRID-NR3 POWERGRID representative agreed to check the reason of sending of DT

from 400 kV Hamirpur to Banala (PG) and it further resulted unto tripping in

the complex as only line available in the complex.

P. Multiple Element tripping at 400kV Akal (Raj) Station at 11:16hrs of 01st Nov 2019 Event category: GD-1 Generation loss (in MW): 1735 MW (Rajasthan may confirm about gen. loss) Loss of load (in MW): Nil (As per Rajasthan report) Energy load (in MU): Nil (As per Rajasthan report) Data Summary received/available at NRLDC:



PMU data 1000ms

Phase of the fault PMU data R-N fault followed by Y-N fault





Preliminary Report Rajasthan Received (Within 24hrs)





Rajasthan



1. Single Line diagram of 400/220 kV Akal (Raj):

2. At 400/220 kV Akal (Raj) station have one and half breaker scheme at 400

kV side. It is connected through Kankani D/C, Ramgarh D/C, Barmer S/C and Jodhpur S/C. It also have three 315 MVA 400/220 kV ICTs & one 500MVA 400/220 kV ICT.

3. 220 kV Akal is connected with 220 kV Akal2 D/C, Bhu D/C, Dangari D/C, Jajiya S/C, Moolana S/C, Lala S/C, Rajgarh S/C, Bhensada S/C, Amarsagar S/C, Mada S/C & Giral S/C. All the lines are importing wind generation toward 400/220 kV Akal station except 220 kV Barmer, Giral and 400/220 kV ICTs

4. At 11:16hrs, 220 kV Giral was feeding through 220 kV Bus-1 at 400/220 kV Akal (Raj). To avoid over load tripping of 220 kV bus coupler shift incharge tried to close 220 kV Bus-2 side isolator of 220 kV Giral feeder on load in the yard by pushing the closing push button. But isolator bar stucked near the jaw of the pole and due to continuous flash over jaw melted and jumper snapped from jaw. It further resulted into earth fault in the system.

5. At the same time multiple 220 kV elements along with all four 400/220 kV ICTs tripped at 400/220 kV Akal (Raj). 400 kV Akal-Ramgarh ckt-2 also tripped on O/V protection.

6. In antecedent condition 220 kV Akal-Giral ckt was connected through 220 kV Bus-1 and being shifted to 220 kV Bus-2 to avoid over current tripping of 220 kV bus coupler.

7. Name of the tripped element: 220 kV Akal-Bhu ckt-1 220 kV Akal-Bhu ckt-2 220 V Akal-Dangri ckt-2 220 kV Akal (400/220kV)-Akal ckt-2 220 kV Akal-Giral ckt 220 kV Akal-Amarsagar ckt 220 kV Bus coupler at Akal station 400/220 kV 315 MVA ICT-1, 2, 3 & 4 at Akal (Raj) 400 kV Akal-Ramgarh ckt-2

8. PMU plots:

9. As per PMU & SCADA data:

As per PMU, Maximum dip in R-phase followed by Y-phase. Fault Clearance time: 1000ms


12. Preliminary Report received within 24hrs & DR/EL details received after 24hrs but detailed report and remedial measures report is still awaited from Rajasthan.

Points for Discussion: 1. Reason of delayed clearance of fault? 2. Healthiness of 220 kV bus bar protection/ LBB at 400/220 kV Akal (Raj)

needs to be checked. 3. Non opening of 220 kV bus coupler at 400/220 kV Akal needs to be

looked into. 4. Reason of tripping of 400/220 kV ICTs at Akal (Raj) from 220 kV side as

mentioned in flag details also needs to be checked in view of directionality of back up over current earth fault protection of ICTs.

5. 220 kV Akal (end)-Bhu ckt-1 & 2 and Akal (end)-Akal ckt-2 didn’t trip in reverse zone (Z-4) instead tripped in Z-1. Distance zone setting (Z-1 & Z-4) needs to be reviewed at 400/220 kV Akal (Raj)

6. All the DR received from Rajasthan have time synch error, sequence of event couldn’t be established because of time synch error. It needs to be addressed on priority.

7. Healthiness of station event logger at 400/220 kV Akal (Raj) also needs to be looked into.


9. Tripping didn’t capture in Rajasthan/ NR SoE. Availability of SCADA digital data in Rajasthan/ NR SoE needs to be ensured.

10. It is suspected that cause of large renewable generation tripping is due to unavailability of FRT/ LVRT capabilities in various wind generating stations. These large scale trippings are serious threat for security of the entire grid and such type of incident also occurred in the past?

11. Multiple times fault occurrence indicate the poor maintenance and protection system at 400/220 kV Akal (Raj). Third party Protection audit needs to be carried out at 400/220 kV Akal (Raj)


No representative from Rajasthan RRVPNL, SLDC-Rajasthan & RRVUNL) was attended the meeting. SE, NRPC raised concern for non-submission of detailed report and no representation in the meeting. .

Q. Multiple Element tripping at 400kV Muzaffarnagar (UP) Station at 03:16hrs of 05th Nov 2019 Event category: GD-1 Generation loss (in MW): 220 (As per UP report) Loss of load (in MW): 150 (As per UP report) Energy load (in MU): __ (UP may confirm) Data Summary received/available at NRLDC:



As per PMU data

Phase of the fault

Y-phase to earth fault & B-phase to earth fault

As per PMU data



Partially Available

Time Synch error



Preliminary Report Uttar Pradesh Received Within 24hrs

POWERGRID Received Within 24hrs

Detailed Report Uttar Pradesh Received




Uttar Pradesh

1. Preliminary Report, DR/EL after 24hrs 2. Detailed Report yet to be received 3. Adequately Sectionalized and graded protective relaying system 4. Incorrect/ mis-operation / unwanted operation of Protection system 5. Delayed Clearance of fault



Based on above information description of the events is: 1. Connectivity diagram of 400/220 kV Muzaffarnagar (UP):

2. At 400/220 kV Muzaffarnagar station have double main transfer breaker scheme at 400 kV side. It is connected through Meerut (PG) S/C, Roorkee (PG) S/C, Ataur S/C, Vishnuprayag S/C and Alaknanda S/C. It also has three 315 MVA 400/220 kV ICTs.

3. Initially Yellow phase fault in zone1 of 400kV Muzaffarnagar- Attaur line was occurred at the time of 03:16:35.819hrs, at this time Yellow phase was opened (attach DR at time of 03:16:35.819) but again fault was occurred in Blue phase of this line at time 03:16:36.494 and thereof SOTF command generated by relay with 186R1, Y1, B1, but Red and Blue phase breaker failed to open. It resulted into delayed clearance of fault.

4. All other 400kV Lines connected at 400 kV Muzaffarnagar (UP) station tripped in Z3 from remote end except 400kV Muzaffarnagar-Vishnuprayag line which was hand tripped by Muzaffarnagar S/S Staff.

5. All three 400/220 kV 315 ICT-I, 315 ICT-II and 315 ICT-III also tripped on back up over current earth fault protection

6. In antecedent condition, one unit of Alaknanda and two units at Vishnuprayag was running.

7. Name of the tripped element: 400kV Muzaffarnagar(UP)-Ataur(UP)

400kV Muzaffarnagar(UP)-Roorkee(PG) 400kV Muzaffarnagar(UP)-Meerut(PG) 400kV Muzaffarnagar(UP)-Vishnuprayag(UP) 400kV Muzaffarnagar(UP)-Alaknanda(UP) 315MVA ICT 1 at 400/220kV Muzaffarnagar(UP) 315MVA ICT 2 at 400/220kV Muzaffarnagar(UP) 315MVA ICT 3 at 400/220kV Muzaffarnagar(UP)

8. PMU plots:

9. As per PMU data: As per PMU, Y-phase to earth fault followed by B-phase to earth fault. Fault Clearance time: 80ms & 1520ms



400 kV Vishnuprayag may check why the line didn’t trip at their end. 400 kV Muzaffarnagar may check LBB (ABB make static relay) for

delayed operation and rectify if any Broken earth wire of 400 kV Muzaffarnagar-Ataur line has been

repaired

13. Preliminary Report received within 24hrs & DR/EL details received after 24hrs but detailed report and remedial measures report is still awaited from UPPTCL.

14. DR/EL details have been received from POWERGRID after 24hrs

Points for Discussion: 1. Reason of failure of R&B-phase breaker of 400 kV Muzaffarnagar UP

(end)-Ataur ckt as fault was in other phase during –phase breaker dead time. (Relay correctly sensed the fault in Z-1 and send tripping command). Breaker over hauling report needs to be shared with NRPC/ NRLDC

2. Healthiness of 400 kV bus bar protection/ LBB at 400/220 kV Muzaffarnagar (UP) needs to be checked.

3. Non tripping of 400 kV bus coupler at 400/220 kV Muzaffarnagar (UP) needs to be looked into.

4. If 400 kV Muzaffarnagar-Vishnuprayag (end) ckt didn’t trip than how fault get clear in 1.5 second.

5. Reason of tripping of running units of Vishnu Prayag needs to be established as 400 kV Vishnuprayag-Alaknanda one ckt & 400 kV

Alaknanda-Srinagar D/C was still connected after multiple element tripping at 400 kV Muzaffarnagar (UP). Vishnuprayag end data was stucked. Is there any island formation at 400 kV Vishnuprayag & Alaknanda units with Srinagar load? Details are still awaited

6. Time synch error and nomenclature issue captured through DR of Muzaffarnagar (UP) end. DR was also received only for 400 kV Muzaffarnagar-Ataur ckt.

7. Healthiness of station event logger at 400/220 kV Muzaffarnagar (UP) needs to be ensured.


9. Vishnuprayag end digital/analog data availability needs to be ensured. 10. Detailed Report and Remedial measures report is still awaited from

UPPTCL.

Discussion during the meeting: 1. UPPTCL representative informed that there was fault in Y-phase of 400

kV Muzaffarnagar (UP)-Attaur ckt and Y-phase breaker tripped, during dead time of the breaker again fault occurred in Blue phase. This time three phase tripping should have occurred but R&B-phase breaker failed to open because of trip ckt faulty alarm. Later on less resistance of trip coil was identified as the main reason for non-operation of breaker. In case of breaker failure, LBB protection should have operated but LBB protection relay was also defective. PDR (Pole discrepancy relay) also didn’t operate due to less coil resistance. Coil resistance may have reduced due to overheating of the trip coils.

2. Remedial action of replacement of trip coil resistance for distance and PDR protection has already been taken on 07th Nov 2019. Defective LBB protection relay has also been replaced on 07th Nov 2019. At present LBB & Bus Bar Protection at 400/220 kV Muzaffarnagar (UP) is in healthy condition.

3. NRLDC representative asked for non-operation of backup over current/ earth fault protection of bus coupler in DMT (double main transfer breaker) scheme. If bus coupler tripped with proper time than there may be chances of saving of some of the elements from tripping.

4. UPPTCL representative informed that bus coupler at 400/220 kV Muzaffarnagar (UP) is worked as a simple switch, there is no dedicated protection available for bus coupler.

5. NRLDC representative asked from the PSC members about the general practice to kept protection for 400 kV bus coupler or not?

6. POWERGRID representative informed that they have very limited station with DMT scheme, they will confirm in next meeting.

7. NRLDC representative requested to all the members to check the protection setting implemented for bus coupler at their own end and this point will be discussed separately in next PSC meeting.

8. Alaknanda representative informed that relays at Vishnuprayag and Alaknanda is not GPS time synch.

9. UPPTCL representative confirmed that event logger is healthy at 400/220 kV Muzaffarnagar (UP) but protection relays are not time synch.

10. Apart from above reason of tripping of 400 kV Vishnuprayag, Alaknanda, Srinagar complex needs to be established. UPPTCL representative agreed to check the remaining points and submit the detailed report in 15days.

R. Multiple Element tripping at 400 kV Jhakri HEP Station at 20:43hrs of 24th Nov 2019 Event category: GD-1 Generation loss (in MW): 600 Loss of load (in MW): Nil Energy load (in MU): Nil Data Summary received/available at NRLDC:



80ms As per PMU data

Phase of the fault R-phase to earth fault

As per PMU data



Available (Partial)

DR/ EL NJPC Received Within 24hrs

JSW Not Received

Preliminary Report NJPC Received Within 24hrs

JSW Not Received

Detailed Report NJPC Not Received




NJPC

1. Preliminary Report, DR/EL within 24hrs 2. Detailed Report yet to be received 3. Adequately Sectionalized and graded protective relaying system


1. IEGC 5.2.r & 5.9.6.c (VI) 2. CEA grid Standard 15.3

JSW 1. Preliminary Report, DR/EL after 24hrs


1. Single Line diagram of 400 kV Jhakri HEP:

2. 400 kV Jhakri HEP station has double main single breaker bus scheme. It is connected through Karcham D/C, Rampur D/C and Panchkula D/C. It also has six units of 250MW.

3. Failure of R-phase breaker at Jhakri end of 400 kV Jhakri-Karcham ckt-2 and further resulted into 400 kV bus bar protection operation at 400 kV bus-2 of Jhakri HEP

4. During opening of 400 kV Karcham-Jhakri ckt-2, Karcham end breaker opened properly but Jhakri end breaker didn't open properly. After some duration R-phase breaker at Jhakri end failed and resulted into 400 kV bus bar protection operation at 400 kV bus-2 of Jhakri HEP. It further resulted into tripping of 400 kV Bus Coupler and 400KV lines i.e. NJ-Rampur-II & Unit#2 which were connected on the same bus bar - II. (NJ-Panchkula-II was already in open Condition). One unit of Rampur Hydro Power Station was also got tripped due to tandem operation.

5. Consequences of tripping of two evacuation line from Jhakri HEP, Planned SPS (Case-3) at NJHPS initiated trip command to Unit#3 (Running) and Unit#5 (Stopped) at NJHPS and subsequently one Unit of Rampur Hydro

6. In antecedent condition, Karcham generation was nil, Two units each at Jhakri and Rampur HEP was running. 400 kV Jhakri-Panchkula ckt-2 was

also under outage. Shutdown code was issued for taking out of 400 kV Karcham-Jhakri ckt-2 on high voltage.

7. Name of the tripped element: 68.67 MW Rampur hep - unit 6 400 kV Nathpa Jhakri(sj)-Rampur hep(sj) (pg) ckt-2 400 kV Bus 2 at Nathpa Jhakri(sj) 250 MW Nathpa-Jhakri hps - unit 2 250 MW Nathpa-Jhakri hps - unit 3 68.67 MW Rampur hep - unit 1 400 kV Nathpa Jhakri(sj)-Karcham Wangtoo(jsw) (hbpcl) ckt-2

8. PMU plots:

9. As per PMU & SCADA data: As per PMU, voltage dip in all three phase & R-phase to earth fault. Fault Clearance time: 80ms SoE didn’t capture for all the tripped element. 400 kV Jhakri-Karcham ckt-2 opened at 20:43:18,640hrs. At 20:43:29,580hrs 400 kV Jhakri-Rampur ckt-2 tripped due to bus bar

protection operation at 400 kV Bus-2 of Jhakri HEP




Points for Discussion: 1. Reason of non-opening & failure of R-phase breaker of 400 kV Jhakri

(end) breaker-Karcham ckt-2 2. Breaker over hauling report needs to be shared for 400 kV Jhakri (end)

breaker-Karcham ckt-2

3. SCADA digital data status didn't capture for all the tripped elements. It needs to be looked into.

4. Station Event Logger output needs to be looked into and sequence of event (in ms) to be shared.

5. DT (direct trip) needs to be mapped in Rampur end DR of 400 kV Jhakri-Rampur ckt-2.

6. Detailed report and remedial measures report needs to be submitted considering the aforesaid points

NJPC may elaborate the incident, submit the detailed report and may also apprise the members about corrective actions already taken/being taken (with time line) to avoid such events.

S. Multiple Element tripping at 400 kV Uri II HEP Station at 09:07hrs of 27th Nov 2019 Event category: GD-1 Generation loss (in MW): 215 Loss of load (in MW): Nil (Information didn’t receive from J&K) Energy load (in MU): Nil (NHPC may confirm about water spillage) Data Summary received/available at NRLDC:





As per PMU data



Available (Partial)

Time Synch error

DR/ EL NHPC Received After 24hrs


Preliminary Report NHPC Received After 24hrs


Detailed Report NHPC Not Received




NHPC

1. Preliminary Report, DR/EL within 24hrs 2. Adequately Sectionalized and graded protective relaying system





1. Single Line diagram of 400 kV Uri2 HEP:

2. 400 kV Uri II HEP station have double main single breaker scheme at 400 kV side. It is connected through Uri1 S/C & Wagoora S/C. It also has four unit of 60 MW each.

3. At 09:07hrs on 27th Nov 19 a fault occurred on Yellow Phase of 400 kV Uri2-Wagoora ckt. Y-phase breaker of Uri2 end open and successfully A/R. 400 kV Uri2-Wagoora ckt tripped from Wagoora end in distance Z-2 protection in 450ms of fault occurrence.

4. 400 kV Uri2-Uri1 ckt tripped from Uri1 end in Z-1 instantaneously. Blue phase along with faulted Y-phase also tripped. It further resulted into continuous fault feeding through R-phase and Uri2 end finally tripped on over current protection.

5. 400 kV Uri-2 HEP units also tripped in 300ms of fault occurrence. 6. Reason of continuous fault feeding despite of tripping of Uri2-Wagoora ckt

from Uri2 end in 80ms yet to be concluded.

7. Name of the tripped element: 400 kV Uri_2(nh)-Wagoora(pg) (pg) ckt-1 400 kV Uri_2(NH)-Uri_1(NH) (PG) Ckt-1 60 MW Uri-II HPS - UNIT 1 60 MW Uri-II HPS - UNIT 2 60 MW Uri-II HPS - UNIT 3

60 MW Uri-II HPS - UNIT 4

8. PMU plots:

9. As per PMU & SCADA data: As per PMU, Y-phase to earth fault. Fault Clearance time: 540ms

Tripping captured in NRLDC SoE. 400 kV Uri2-Uri1 ckt tripped from Uri2 end after 220ms of fault

occurrence. 400 kV Wagoora-Uri2 ckt tripped from Wagoora end after 640ms of

fault occurrence. Uri-2 end breaker tripping didn’t capture





Points for Discussion: 1. Exact reason and location of fault. 2. Reason of delayed clearance of fault. 3. Reason of Uri2 unit tripping needs to be established. 4. Reason of R-phase current in 400 kV Uri2-Uri1 ckt for more than 1 second

needs to be looked into? 5. Carrier communication in 400 kV Uri2-Wagoora ckt needs to be checked

and corrected. One to one testing of PLCC to be done. 6. Distance Z-1 protection setting of 400 kV Uri1 (end)-Uri2 ckt needs to be

reviewed in view of distance over reach, tripping of two phases (Y&B-phase) instead of Y-phase & two phase tripping instead of all three phase.

7. Over current setting in 400 kV Uri2-Uri1 ckt needs to be disabled. 8. Time Synchronization of all the DRs at 400 kV Uri2 HEP needs to be

corrected. 9. Detailed report and remedial measures report needs to be submitted

considering the aforesaid points Discussion during the meeting:

1. NHPC representative has showed the presentation during the meeting and same is attached as Annexure-VI.f

2. Connectivity and location of fault:

27/11/2019: Uri-I & II

Transient Fault was in Y-phase

3. Y-phase to earth fault in 400 kV Uri II-Wagoora ckt at 1.28kM from Uri II end. Line successfully A/R from Uri II end. Carrier communication was not working in the line and Wagoora end line tripped in Z-2.

4. POWERGRID representative confirmed that PLCC carrier scheme has been checked and corrected in last week.

5. Analysis Uri I-Uri II ckt: Fault seen by Uri-I end relay in Zone-I (Y-ph). Instead of only Y-ph, both Y & B phase got opened. All the Power from Uri-II PS flown through single phase causing

transformer neutral O/C & tripped the units. Uri-II GT have sensitive over current earth fault protection (on OeM

recommendation) to protect the unit for earth fault on neutral side of the transformer. Setting value is 0.5 PU and 500ms. GT tripped on this stage-2 protection and further resulted into tripping of units on over frequency/ over speed. OeM recommended this setting after failure of one of the GT in the past and fault in the neutral side may not picked by GT differential protection thatswhy we don’t want to change the setting.

6. At present DRs at Uri-II is GPS time synch however it will be once again checked with the site in next 1-2 months.

7. Over current setting in 400 kV Uri2-Uri1 ckt was based on OeM recommendation. It will be once again discussed with OeM and revert back to NRPC/ NRLDC.

T. Multiple Element tripping at 220 kV Samaypur BBMB at 15:05hrs of 30th Nov 2019 Event category: GD-1 Generation loss (in MW): Nil Loss of load (in MW): 200 Energy load (in MU): ___ (Haryana didn’t inform about energy loss) Data Summary received/available at NRLDC:





As per PMU data



Available (Partial)

DR/ EL

BBMB Received After 24hrs

Haryana Not Received

POWERGRID Not Received

Preliminary Report

BBMB Received Within 24hrs

Haryana Not Received After 24hrs

POWERGRID Not Received After 24hrs

Detailed Report BBMB Not Received




BBMB




POWERGRID & Haryana

1. Preliminary Report, DR/EL after 24hrs


1. Single Line diagram of 220 kV Samaypur BBMB:

2. At 220 kV Samaypur (BBMB) station have double main single breaker scheme at 220 kV side. It is connected through Ballabhgarh (BBMB) triple ckt, Faridabad Gas D/C, Palli D/C, Badshahpur D/C, Palwal D/C &

Charkhi Dadri S/C. It also have four 500 MVA 400/220 kV ICTs which are connected to 400 kV Ballabhgarh (PG).

3. At 15:04hrs on 30th Nov 19 a fault occurred on Yellow Phase of 220 kV Samaypur-FGPP 1 (PGCIL Line) at a distance of 2.292 kM in zone 1. Fault current shown by relays is 36kA. The circuit breaker could not clear the fault after 200ms it’s LBB protection operated and finally its yellow phase bursted. Y phase LA and line isolator also got damaged. Other circuit breaker also opened due to the operation LBB protection of 220KV Samaypur (end)-FGPP 1.

4. Setting of LBB is 0.2A & time Delay 200ms. As per the DR, Actual current flowing in primary was 37190 Amp at the time of operation of LBB.

5. After isolating 220 kV Samaypur FGPP 1 from the system other system was normalized by 17:31 Hrs except 220 KV bus coupler 1 due to the problem in circuit breaker developed while its closing. Thus Bus 1 was charged through Bus Coupler 2.

6. Reason of delayed clearance of fault was due to breaker failed to open and subsequently operation of LBB protection t 220 kV Samaypur (BBMB).

7. Name of the tripped element: 220kV bus 1 at Samaypur(BBMB) 220 kV Faridabad(PG)-Samaypur(BB) (UNDEF) Ckt-1, 220kV Ballabhgarh-Samaypur (BB) Ckt-2, 220kV Ballabhgarh-Samaypur (BB) Ckt-3, 220kV Palwal(HV)-Samaypur(BB) (UNDEF) Ckt-1, 220kV Samaypur(BB)-Badshahpur(HV) (UNDEF) Ckt-2, 400/220 kV 500 MVA ICT 1 at Ballabhgarh(PG), 400/220 kV 500 MVA ICT 2 at Ballabhgarh(PG), 400/220 kV 500 MVA ICT 4 at Ballabhgarh(PG), 220 kV Samaypur(BBMB)-Palli ckt-2

8. PMU plots:

9. As per PMU & SCADA data: As per PMU, Y-phase to earth fault. Fault Clearance time: 460ms Tripping captured in BBMB SoE for 220 kV elements but ICTs tripping

didn’t capture in BBMB SoE & NRLDC SoE. 220 kV Bus Coupler-2 a 220 kV Samaypur (BBMB) tripped after

360ms of inception of fault. 220 kV Faridabad end of 220 kV Samaypur BBMB-Faridabad ckt-1

tripped after 450ms of inception of fault.



12. Preliminary Report received within 24hrs & DR/EL details along with detailed report received after 24hrs from BBMB.

13. Preliminary Report, DR/EL and detailed report is still awaited from Haryana


1. Reason of delayed opening of 220 kV Bus Coupler-2 at Samaypur (BBMB).

2. Reason of delayed tripping of 220 kV Samaypur BBMB-Faridabad ckt-1 at 220 kV Faridabad end. (Haryana may kindly check and report). In case of Z-2 tripping why carrier communication didn’t work between these two station.

3. Uneven distribution of load through 220 kV bus as three 400/220 kV ICTs were connected on 220 kV Bus-1?

4. SoE of ICTs tripping at 220 kV Samaypur (BBMB) didn’t capture in BBMB & NR SoE. Are these ICTs tripped or not? In case of tripping of ICTs from 220 kV side, inter tripping from 400 kV side also needs to be looked into.

5. Time Synchronization of all the DRs at 220 kV Samaypur (BBMB) needs to be corrected.

6. Availability of Analog and Digital data of 400/220 kV Ballabhgarh (PG) ICTs needs to be looked into

Point wise reply and discussion during the meeting:

1. BBMB representative gave presentation during the meeting, same is attached as Annexure-VI.g

2. Reason of delayed opening of 220 kV Bus Coupler-2 at Samaypur (BBMB): BBMB agreed to check the reason of delayed opening of bus coupler in view of actual delayed operation or SoE time synch error.

3. Reason of delayed tripping of 220 kV Samaypur BBMB-Faridabad ckt-1 at 220 kV Faridabad end. (Haryana/ NTPC may kindly check and report). In case of Z-2 tripping why carrier communication didn’t work between these two station:

30.11.19 / 15:04 Hrs, Yellow phase fault was on 220kV Samaypur-FGGP-1.

15:04:10:30, any Trip B: ON due to Y- ph fault on FGPP ckt-1 at 2.292 Km.

Operation of MiCOM P444 of FGPP-1 was in order and trip command to Y-pole was extended.

Y- Pole opened but fault current of about 36 kA could not interrupted after opening of Circuit Breaker.

LBB of FGPP -1 operated after 200ms of any trip command from D.P. Scheme of FGPP Ckt-1

Feeders connected on Bus-1 tripped through 96 trip relays. Simultaneously, Y- pole C.B. of FGPP -1 damaged. Other end

(FGPP end) tripped in Zone-2.

Behavior of protection system was in order Y-Pole interrupter chamber of 245kV SF-6 ABB make Circuit

Breaker. Year of manufacturing – 1988. Year of commissioning: 1999.

Y-Phase 198kV CGL make L.A. Year of manufacturing & commissioning: 1998 & 1999.

Overhauling of C.B. in 2015 (only drive mechanism). Breaker operating time and CRM were normal during last periodical

testing on 16.05.19. No abnormality was observed in the breaker before failure. Exact reason of damage of pole could not be ascertained. BBMB representative further confirmed that carrier was send

in 220 kV Samaypur-Faridabad ckt-1 (faulted line) however NTPC representative informed that carrier communication didn’t received at Faridabad end.

4. Uneven distribution of load through 220 kV bus as three 400/220 kV ICTs were connected on 220 kV Bus-1:

Male & Female contact assembly along with arm of Y-phase 220kV Bus 2A isolator of ICT-4 got damaged in past. Spare isolator arm and male / female assembly are being arranged and will be replaced shortly.

Bus-II isolator of ICT-1 & 2 has hot points on female & male contacts. Male and Female jaw assembly is being arranged and will be replaced shortly.

5. BBMB representative informed that station event logger is not in service but they are in the process of implementation of automatic online logging of station events at dedicated PC. Implementation will be completed in 6 months.

6. NRLDC representative further raised concern for unhealthy station event log at many of the 220 kV stations in Northern Region and requested to NRPC to take up it as a regular agenda from next meeting.

7. SoE of ICTs tripping at 220 kV Samaypur (BBMB) didn’t capture in BBMB & NR SoE. Are these ICTs tripped or not? In case of tripping of ICTs from 220 kV side, inter tripping from 400 kV side also needs to be looked into: BBMB representative agreed to check the SoE for digital signal of ICTs.

8. Time Synchronization of all the DRs at 220 kV Samaypur (BBMB) needs to be corrected: GPS at 220 kV Samaypur (BBMB) didn’t time synch, it will be checked and corrected.

9. Availability of Analog and Digital data of 400/220 kV Ballabhgarh (PG) ICTs needs to be looked into: POWERGRID representative informed that inter-tripping was not occurred during the incident. POWERGRID agreed to check the analog data of 400 kV Ballabhgarh (PG).

U. Complete Station Outage of 400 kV Dasna (UP) at 15:08hrs of 30th Nov 2019 Event category: GD-1 Generation loss (in MW): Nil Loss of load (in MW): 36 Energy load (in MU): __ (UP may confirm) Data Summary received/available at NRLDC:



PMU data 80ms

Phase of the fault

PMU data Y-phase to earth fault



Uttar Pradesh Available (Partial)

DR/EL Uttar Pradesh Received

Preliminary Report

Uttar Pradesh Received




1. IEGC 5.2.r & 5.9.6.c (VI) 2. CEA (Technical standards for connectivity to the Grid) Regulation, 2007: Schedule Part 1. ( 6.1, 6.2) 3. 43.4.A & 43.4.D of CEA Technical Standard for Construction of Electrical Plants and Electric Lines; CEA (Technical standards for connectivity to the Grid) Regulation, 2007: Schedule Part 1. ( 6.1, 6.2, 6.3, 6.4) CEA (Technical standard for connectivity to the Grid, Amendment Regulation

Uttar Pradesh


2013), part-II, B2


1. Single Line diagram of 400 kV Dasna UP:

2. At 400/220 kV Dasna station have double main transfer breaker scheme at 400 kV side. It is connected through Hapur (UP) D/C. It also have two 315 MVA 400/220 kV ICTs.

3. In antecedent condition 400 kV Bus-2 of Dasna (UP) was under outage. Bus Bar Protection operated at 400 kV Bus-1 of 400/220 kV Dasna (UP).

It further resulted into tripping of all the connected elements namely 400 kV Hapur-Dasna ckt-1 & 2, 400/220 kV 315 MVA ICT-1 & 2 at 400 kV Dasna (UP

4. Name of the tripped element: 400 kV Hapur-Dasna (UP) ckt-2, 400/220 kV 315 MVA ICT 1 at Dasna(UP), 400/220 kV 315 MVA ICT 2 at Dasna(UP), 400 kV Bus 1 at Dasna(UP), 400 kV Hapur-Dasna (UP) Ckt-1

5. PMU plots:

6. As per PMU & SCADA data: As per PMU, Y-phase to earth fault. Fault Clearance time: 80ms Tripping captured in UP SoE for ICTs at Dasna (UP)


9. Preliminary Report received within 24hrs & DR/EL details received after

24hrs but detailed report and remedial measures report is still awaited from UPPTCL

Points for Discussion: 1. Exact location and nature of fault 2. Reason of outage of 400 kV Bus-1 at 400/220 kV Dasna (UP) in

antecedent condition. 3. Reason of operation of bus bar protection in view of actual bus fault or

mal-operation of bus bar protection for through fault condition? 4. Exact sequence of events in view of cause of event; protection


5. Availability of Analog and Digital data of 400 kV Dasna (UP) needs to be looked into.

6. Detailed report in NRPC approved format along with remedial measures report needs to be submitted


1. WUPPTCL representative informed that 400kV Hapur-I&II, ICT(315MVA)-I&II these four feeders were in service with 400 kV Bus-II connection. 400 kV Bus-I & BC (bus coupler) were out service for HV testing after replacing the flashover components in G9 partition of BC (red phase). Earlier 400 kV G9 section of BC (bus coupler) in Red phase got flash over and attended & replaced the same.

2. After HV test, Normalcy restored with 400 kV BUS-2. Later 400 kV Bus-I test charged through Bus Coupler-Circuit Breaker, but both 400 kV Bus – I & II got tripped on ‘Y’ ph, Bus Bar protection and caused for interruption of 400kV Hapur – Dasna Ckt- I & II and 315 MVA ICT 1 & 2 on 30-11-2019 at 15:10 hrs. There was actual bus fault for 400 kV Bus-1 at Dasna (UP). All the 400 kV elements tripped immediately on operation of bus bar protection.

3. WUPPTCL isolated Bus-I and request for code to charge 400kV Bus-II. After receipt of code 400kV Bus-II charged and normalcy restored on 30th Nov 2019.

4. Gas analysis conducted in all partitions of BUS-I, BC, PT-1. Observed SO2 in PT-1-yellow phase, also found it got flash over. WUPPTCL will try to complete the replacement work and HV test within a week.

5. POWERGRID representative suggested that in case of charging of bus through bus coupler in case of fault in upcoming bus, bus coupler should have tripped.

6. POWERGRID and Adani representative suggested to WUPPTCL for permanent selection of Bus coupler CT so that it will be tripped before operation of both bus bar protections.

7. WUPPTCL engineer agreed to take up the matter with OeM and take corrective action.

8. NRLDC representative further informed that soft copy (.dat & .cfg file) didn’t share by WUPPTCL and requested for sharing of the same.

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1

UPPTCL- Transmission Central

400 kV s/s Sultanpur

Tripping on 09.06.2019 (22:55hrs)

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Bus Position and load at 400KV S/S, Sultanpur at 22:00hrs

Name of Equipments Bus Position on 400KV Side Load (Imp/Exp) in MW

315 MVA ICT-I A Bus 170 MW (Exp)

240 MVA ICT-II A Bus 122 MW (Exp)

315 MVA ICT-III A Bus 170 MW(Exp)

400KV Sultanpur-Lucknow (PG) line A Bus 38 MW (Exp)

400KV Sultanpur- NTPC Tanda line A Bus 67 MW (Exp)

400KV Sultanpur-Anpara (Obra) line B Bus 491 MW (Imp)

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Main2 DPR of 400kV Sult-Tanda(NTPC) Line at Sult end

Main2 DPR of 400kV Sult-Tanda(NTPC) Line at Sult end

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Main1 DPR of 400kV Tanda - Sult Line at Tanda(NTPC) end


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Main1 DPR of 400kV Anpara- Sult Line at Anpara end

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Main1 DPR of 400kV Anpara- Sult Line at Anpara end

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Highlights

• Cause of Event• CT (BBC make 1986 mfg) failure of 400kV Sultanpur-

Tanda(NTPC) Line at Sultanpur end- first Bph & then Yph

• Action Taken• All the CTs (BBC make 1986 mfg) of 400kV Sultanpur-

Tanda(NTPC) Line replaced at Sultanpur end.• Bus Isolator contact status of ICT-III set right.• Measures to be taken in Future• Replacement of very old equipments in phased manner• Better Vigilance

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Thank you

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1

UPPTCL- Transmission Central

400 kV s/s Bareilly

Tripping on 24.06.2019 (10:31hrs)

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2

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220kV Bly-C.B.Ganj-II Line

Wave Trap

• On 24.06.2019

• at 10:31hrs

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Highlights

• Cause of Event

• Fault on newly energised 220kV C.B. Ganj II bay (probably due to Rph Wave Trap) was not cleared by main C.B. due to non operation of relay (CT secondary reportedly found shorted)

• Action Taken

• Fault rectified.

• Measures to be taken in Future

• Better Vigilance

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Thank you

30-01-2020

1

Complete Station Outage of 400 kV Jodhpur (RAJ)

03.07.2019 at 16:13:21 hrs

Antecedent Condition and Tripped ElementsAntecedent Condition:-NR demand Met : 62610 MW

Rajasthan Demand : 10350 MW

Frequency : 49.95 Hz.

Generation Loss/Load Loss: Nil

Following elements tripped at 16:13:21 hrs at 400/220 KV Jodhpur Sub-station :-

i. 400 KV Bus I & II

ii. 315 MVA ICT-I & II

iii. 400 kV Jodhpur- Kankani-I & II

iv. 400 kV Jodhpur-Kankroli

v. 400 kV Jodhpur-Bhadla

vi. 400 kV Jodhpur-Akal

vii. 400 kV Jodhpur-Rajwest

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Connectivity Diagram

SLD of Jodhpur (RAJ)

• Constituent Details\Rajasthan\DR_03.07.2019\SLD 400 KV GSS SURPURA (JODHPUR).pdf

Constituent Details/Rajasthan/DR_03.07.2019/SLD 400 KV GSS SURPURA (JODHPUR).pdf

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PMU Plot of phase voltage magnitude at Ratangarh(Raj)

16:13hrs/03-July-19

16:13:21.120hrs

16:13:21.240hrs 16:13:21.440hrs

16:13:22.560hrs

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SLD of 400kV Jodhpur(Raj) before the incident16:12hrs/03-July-19

315MVA ICT-I & II carrying 129MW &

125MW respectively.

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SLD of 400kV Jodhpur(Raj) after the incident16:18hrs/03-July-19

Data Suspected.

Constituent Details (RAJASTHAN DETAILED REPORT)

• Constituent Details\Rajasthan\Detailed report bus bar A.docx

Constituent Details/Rajasthan/Detailed report bus bar A.docx

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Extract of Rajasthan reportNAME OF LINE

TRIPPING

DATE

TRIPPING

TIME

CLOSING

DATE

CLOSING


400/220kV, 315 MVA T/F

ALSTOM make

03/07/2019 16:12 Hrs 03/07/2019 19:40 Hrs Master Trip Relay 86A & 86B Optd Bus Bar A Operated

(Damaged)

400/220kV, 315 MVA T/F

BHEL make03/07/2019 16:12 Hrs 03/07/2019 20:36 Hrs Master Trip Relay 86A & 86B Optd

Bus Bar A Operated

(Damaged)

220 kV ILT Ist 03/07/2019 16:12 Hrs 03/07/2019 19:38 Hrs Master Trip Relay 86L OptdBus Bar A Operated

(Damaged)

220 kV ILT IInd 03/07/2019 16:12 Hrs 03/07/2019 20:37 Hrs Master Trip Relay 86L OptdBus Bar A Operated

(Damaged)

400 kV Ju-Kankani 1st 03/07/2019 16:12 Hrs Master Trip Relay 86A & 86B OptdBus Bar A Operated

(Damaged)

400 kV Ju-Kankani 2nd 03/07/2019 16:12 Hrs 03/07/2019 21:18 Hrs Master Trip Relay 186A & 186B OptdBus Bar A Operated

(Damaged)

400 kV Ju-Rajwest 03/07/2019 16:12 Hrs 03/07/2019 21:32 Hrs Master Trip Relay 186A & 186B Optd

Bus Bar A Operated

(Damaged)

400 kV Ju-Akal 03/07/2019 16:12 Hrs 03/07/2019 19:56 Hrs Master Trip Relay 186A & 186B OptdBus Bar A Operated

(Damaged)

400 kV Ju-Bhadla 03/07/2019 16:12 Hrs 03/07/2019 21:48 Hrs Master Trip Relay 186A & 186B OptdBus Bar A Operated

(Damaged)

400 kV Ju-Kankaroli 03/07/2019 16:20 Hrs 03/07/2019 20:23 Hrs Manually Tripped Manually tripped

220/132 kV 100MVA T/F 03/07/2019 16:12 Hrs 03/07/2019 20:58 Hrs Inter Trip-

132 kV I/C 03/07/2019 16:12 Hrs 03/07/2019 20:59 Hrs O/C ,E/F Relay (27 trip)-

DETAILED TRIPPING ANALYSIS

AND

OBSERVATIONS EACH END WISE

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JODHPUR (RAJ) END

Jodhpur (Raj) End DRs and ELs.

1. AKAL LINE - AKAL LINE JODHPUR END

2. KANKANI LINE - 1 - KANKANI LINE - 1 JODHPUR END

3. KANKANI LINE -2 - KANKANI LINE -2 JODHPUR END

4. RAJWEST LINE - RAJWEST LINE JODHPUR END

5. KANKAROLI (PG) - NOT SUBMITED

6. BHADALA(RAJ) LINE - BHADALA LINE JODHPUR END

7. ICT – 1 & 2 AT JODHPUR – NOT SUBMITTED

8. BUS BAR PROTECTION DR – NOT SUBMITTED

9. STATION EVENT LOGGER - NOT SUBMITTED

JODHPUR (RAJ) END

Jodhpur (Raj) End Observations:

1. All the DRs sent are of different time instant and therefore are of no use in analysis.

2. Bus bar protection DRs not submitted.

3. Station Event logger not submitted.

4. From PMU the fault clearing time comes out to 1.2 sec.

5. Lines have tripped in Zone – 2 from remote ends.

6. Operation of Busbar protection not as expected.

Constituent Details/Rajasthan/DR_03.07.2019/DR 400 SURPURA 03 07 19/03 07 19 surpura_agsys/P442 400KV AKAL/1/DR/Wednesday 03 July 2019 16.07.27.000.CFG

Constituent Details/Rajasthan/DR_03.07.2019/DR 400 SURPURA 03 07 19/03 07 19 surpura_agsys/P444 distance m1 kankani-1/1/DR/Wednesday 03 July 2019 12.43.35.000.CFG

Constituent Details/Rajasthan/DR_03.07.2019/DR 400 SURPURA 03 07 19/03 07 19 surpura_agsys/P442 kankani-2 M1/1/DR/Wednesday 03 July 2019 11.29.10.000.CFG

Constituent Details/Rajasthan/DR_03.07.2019/DR 400 SURPURA 03 07 19/03 07 19 surpura_agsys/P442 400KV RAJWEST M1/1/DR/Wednesday 03 July 2019 12.32.04.000.CFG

Constituent Details/Rajasthan/DR_03.07.2019/DR 400 SURPURA 03 07 19/03 07 19 surpura_agsys/P442 400KV BHADLA M1/1/DR/Wednesday 03 July 2019 12.33.13.000.CFG

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BHADLA (RAJ) END

Bhadla (Raj) End DRs and ELs.

1. JODHPUR LINE BHADLA END DR

OBSERVATIONS:1. Time synchronization in relay to be checked. Not matching with PG Kankaroli.2. Line tripped on Z-2 after a time delay of 80 ms. Seems Zone – 2 timer is wrongly set at

80 ms.3. Fault appearing to be present in R-Y phases.4. Station Event logger not submitted.

Kankaroli (PG) END

Kankaroli (PG) End DRs and ELs.

1. Constituent Details\PG-NR1\03.07.19_Kankroli-Jodhpur_Zone-2\7SA522.CFG2. Constituent Details\PG-NR1\03.07.19_Kankroli-Jodhpur_Zone-

2\AA1C1Q1A2201907033e3.cfgOBSERVATIONS:1. Line tripped on Z-2 after a time delay of 350 ms.2. Fault appearing to be present in Y-B phases at start and then propagating to R-Y-

B-E fault.3. Y & B Phase voltages becoming zero at 393 ms after fault and R- phase voltage

persisting upto 1.5 sec after fault.4. Station Event logger not submitted.

Constituent Details/Rajasthan/DR_03.07.2019/400 KV Bhadhla Trip 03.07/400 KV JODHPUR TRIP 03.07_agsys/P442 M1 JODHPUR LINE/1/DR/Wednesday 03 July 2019 16.12.18.000.CFG

Constituent Details/PG-NR1/03.07.19_Kankroli-Jodhpur_Zone-2/7SA522.CFG

Constituent Details/PG-NR1/03.07.19_Kankroli-Jodhpur_Zone-2/AA1C1Q1A2201907033e3.cfg

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DR of 400 kV Kankroli (end)-Jodhpur

Z-2 tripping

Observations Event Category: GI-2

Generation Loss: Nil

Load Loss: Nil (Rajasthan may confirm about load loss )

Analysis of tripping (As reported):

At 400/220 kV Jodhpur (Raj) station have one and half breaker scheme. It is connectedthrough Kankani D/C, Rajwest S/C, Kankroli S/C, Akal S/C & Bhadla (Raj) S/C. It alsohave two 315 MVA 400/220 kV ICTs.

Due to heavy storm and rain, Bus Post Insulator of 400 kV Bus-I broken and fall downon other live conductor. Bus bar protection of 400 kV Bus-I & II at 400/220kVJodhpur(Raj) operated and all 400 kV lines and 400/220 kV ICT at Jodhpur (Raj) tripped.As per PMU, Voltage dip in all three phases is observed. In antecedent conditions,315MVA ICT-I & II carrying 129MW & 125MW respectively

AT 400 KV GSS SURPURA-400 KV BUS 'A' DAMAGED due to heavy rain & Storm and busbar protection scheme of BUS'A" operated. 400 kV Surpura-Kankraoli Line didn’t tripdue to non operation of 296A relay of bus bar scheme of BUS A hence resulted intripping of Kankani-II, Rajwest & Kankroli lines in zone-II. Both 315 MVA ILTtransformers tripped on backup protection from 220 kV Side and inter tripped on 400kV Side. The Akal line connected with Bus A tripped with operation of bus bar and sentDT to Akal end since Breaker B was already out of circuit.

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ObservationsAnalysis of tripping (As reported):

Preliminary Report and DR details (partial) received after 24hrs from Rajasthan. StationEvent logger details didn’t submit.

DR details received within 24hrs from POWERGRID, station event logger details didn’tsubmit.

ObservationsAs per PMU, SCADA data:

As per PMU, Voltage dip in all three phase.


SoE didn’t capture in Rajasthan SoE.

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Points for Discussion Exact location and nature of fault?

Operation of both the bus bar protection needs to be looked into.

Complete station outage & delayed clearance of fault in case of correct busbar protection operation at 400 kV Jodhpur (Raj) needs to be looked into?

Healthiness of 400/220 kV bus bar protection at Jodhpur (Raj) needs to bechecked and corrected.

Exact sequence of events in view of cause of event; protectionoperation/non-operation; opening, closing of breaker, isolator; relevantalarms and any other relevant detail to be shared.

Healthiness of station event logger at 400/220 kV Jodhpur (Raj) needs to beensured.

Digital breaker status of 400 kV tripped elements & Analog data of outgoingline from 400 kV Jodhpur (Raj) needs to be checked and corrected.

Detailed Report and Remedial measures report is still awaited fromRajasthan.

Presentation by

Praveen Kumar

DGM

Date & Time of Event: 26.07.2019 at 17:43 Hrs

Substations affected: 400 kV Wagoora and NewWanpoh.

Date & Time of Restoration: 26.07.2019 at 18:35 Hrs

At 400 kV Level Wagoora station is connected to Uri-1 PH through Amargarh station, to Uri-2 PH directly and rest of grid via New Wanpoh & Kishenpur stations.

At 220 kV Level there are six feeder connected to Pampore, Zainakote and Kishenganga HEP all on D/C towers.

All 400 and 220 kV lines and ICTs were in service with following load distribution on 220 kV side:

315 MVA ICT-1 & 3 were connected to bus-1.

315 MVA ICT-2 & 4 were connected to bus-2.

220 kV Pampore -1 & Zainakot-1 were connected to bus -1

220 kV Pampore -2 & Zainakot-2 were connected to bus -2

400 kV New Wanpoh Wagoora I & II in service

400 kV New Wanpoh Kishenpur I, II, III and IV in service.

Both ICTs and SVC in service

Generation Loss/Load Loss: 500 MW (Approx)

Sl No Element Tripped Time Remarks

1 220 kV Wagoora Pampore-2 17:43:38.718 Tripped from Pampore.

2 315 MVA ICT-4 17:43:39.160 Tripped on BU impedance.

3 220 kV Wagoora Zainakote-1 17:43:39.164 Tripped in reverse zone at

Wagoora

Z2 operated, Main & Tie CB

Trip

4 220 kV Wagoora Zainakote-2 17:43:39.182

5 315 MVA ICT-2 17:43:39.899 Tripped on OC EF.

6 315 MVA ICT-3 17:43:39.899 Tripped on OC EF.

7 220 kV Wagoora Pampore-1 17:43:40.269 Tripped from Pampore.

8 +200/-300 MVAr SVC N Wanpoh 17:43:39.889 Tripped on Neutral OC of

coupling transformer.

•Name and time of the tripped elements in time chronology:

At Wagoora:

220 kV Wagoora- Kishenganga D/C was to be charged from Wagoora as an anti-theft measure. Two days back there was an incident of jumper cutting and the line route is full of ROW issues. As the lines were to be charged for the first time and keeping in view the other issues as above to avoid unwanted tripping occurrence, it was thought that the entire load would be shifted to 220 kV bus-2 and the new lines would be charged from bus-1.

Load shifting was started and 220 kV Pampore-1 line was put on bus-2 by closing 20789B isolator and opening 20789A isolator. While shifting ICT-1 bay-209 to bus-2, 20989B isolator was closed and 20989A isolator (connected to bus-1) was opened. As it got opened its bus side jumper along with isolator arm snapped due to breaking of head of the BPI on which it was resting. This resulted in fault on 220 kV bus-1.

Bus bar protection did not operate as it was blocked due non-switching of CT after isolator operation.

Y-ph Bus-1 jumper with isolator arm

Bus-2 isolator (20789B) of 220 kV Pampore-1 line was closed at 17:37 hrs.

Bus-1 isolator (20789A) of Pampore-1 line opened after closing of B-isolator.

Next, bus-2 isolator (20989B) of ICT-1 was closed at 17:40:25 hrs. Bus-1 isolator (20989A) of ICT-1 was opened at 17:43:33 hrs. Isolator auxiliary contacts did not switch correctly resulting in

improper CT switching. Bus bar protection went in block mode as CT switching has not taken place after 5 sec.

Bus-1 side jumper along with arm and terminal connector assembly of 20989A isolator of ICT-1 snapped due to breaking of head of the BPI on which it was resting.

This created bus fault on bus-1. Bus bar protection was in blocked condition hence did not operate.

Bus fault was created by breaking of isolator BPI at 17:43:38.628 hrs.

220 kV Pampore – 1 & 2 lines opened from Pampore end in zone-2 17:43:40.269 and 17:43:38.718 hrs repectively.

220 kV Zainakote – 1 & 2 lines opened at Wagoora in reverse zone at 17:43:39.164 and 17:43:39.182 hrs respectively.

ICT-2 tripped on HV Over Current protection operation at 17:43:39.899 hrs.

ICT-3 tripped on HV Over Current protection operation at 17:43:39.899 hrs.

ICT-4 tripped on Backup Impedance protection operation at 17:43:39.160 hrs.

Bus coupler tripped at 17:43:46 hrs which cleared the fault.

220 kV Zainakote-1 and ICT-3 were feeding the fault directly as these were still connected to bus-1. 220 kV Pampore-1 & 2, ICT-1, 2 & 4 were feeding the fault through bus coupler as these elements were connected to bus-2.

Bus Bar protection was in blocked mode hence did not operate.

Pampore lines tripped from JKPDD Pampore end.

Zainakote lines tripped in reverse zone which is correct operation.

ICT-1 did not trip which is unacceptable. It would have tripped on BU OC protection. Voltage selection scheme was not working and voltage did not appear to BU OC & EF relay leading to its non-operation. Back up Impedance function was left disabled in the new HV BU OC EF relay which was retrofitted in July’19.


ICT-3 tripped on HV BU OC & EF protection operation. Back Impedance function was kept disabled resulting in its non-operation of Back up IMP protection. ICT-3 DR

ICT-2 DR

Wagoora/Wagoora Multiple Tripping 26072019/20190726 DR/ICT-3/ICT3_HV_BUI.CFG




ICT-4 got isolated by operation of Back up Impedance which was enabled in HV CO EF relay. This was a desired operation.

Finally fault got isolated by opening of Bus Coupler on is OC relay operation.

It was found that protection configuration had some issues which needed to be resolved immediately. All the settings and functions have been done as per recommendations.

Due to auxiliary contact switching issues, isolator opening closing event did not captured in the events. Moreover some of the BCUs installed for remote operation also found out of time sync.

ICT-4 DR

Wagoora/Wagoora Multiple Tripping 26072019/20190726 DR/ICT-4/ICT-4_HV_BUI.CFG

Wagoora/Wagoora Multiple Tripping 26072019/20190726 DR/ICT-4/ICT-4_HV_BUI.CFG

SVC at New Wanpoh tripped at 17:43:39.889 hrs on neutral over current protection (50Z) operation for coupling transformer. The setting for this protection is 0.44 Amp and 1.2 Sec.

After the occurrence of fault, there was imbalance in system voltage. Y-ph voltage was reduced due to fault in that phase and same also reflected at New Wanpoh. SVC tried to correct this voltage drop, TSC had been put into service. But the voltage in B-ph rose to 260 kV which led to the outage of TSC due to high current. From the DR it can be seen that TSC has been switched in thrice as MVAr has risen thrice during the disturbance.

During this disturbance the neutral over current has gone above the set value of protection operation and persisted for 1.2 Sec which led to the tripping.

SVC DRN WnphEvents

SVC_N Wanph_26072019_trip/Trip DFR DR/DR.cfg

SVC_N Wanph_26072019_trip/Trip DFR DR/DR.cfg

SVC_N Wanph_26072019_trip/Events/Events 26072019.pdf

◦ Non operative Bus bar protection due to CT switching problem. If the bus bar protection would have operated, nothing would have gone abnormal and cascaded tripping of other elements would have not occurred.

◦ Unreliable isolator Auxiliary contact: Isolators are very old and auxiliary contact operation is unreliable.

◦ Disabling of Backup IMP protection: Distance protection was left disabled in HV BU OC EF relays since retrofitting resulting in non-operation of protection.

◦ Non operation of Voltage selection scheme: VT selection relay of protection has not been selected, results in non-availability of VT at ICT 1 leading to OC E/F. The magnitude of the current had not gone to high set value and OC EF was the only protection to operate. The cause for VT selection problem is also attributed to auxiliary contact of isolators.

To avoid reoccurrence of such incident following needs to carried outurgently:

Isolator mechanism boxes need to be replaced at the earliest – Thecase is already under process for replacement of isolators.

Protection functions/schemes shall be corrected as perrecommendations and approved drawings -- The settings andconfiguration has been corrected as desired.

Automation schemes such as VT selection, CT switching, Isolatorinterlocks etc. need to be made functional as possible till thereplacement of Isolators.

Time synchronization of BCU need to be done -- has been done andunder continuous monitoring for healthiness.

It was observed that crack had developed earlier in the broken BPI atthe joint of porcelain and metallic portion. It has also been instructedto the stations to visually inspect for such things during bus shutdowns so that mechanical failures like this may be avoided.

1

Multiple element tripping (A8.14) analysis report

POWERGRID Agra Substation

Date of incident: 07.10.2019

Pre Incident system Conditions

2

NEA HVDC: All 04 poles in service (normal direction)

765kV System: All lines, Bus Reactors, Line reactors and

ICTs in service except 765kV Agra

Fatehpur-2 line

400kV System: All lines, 400/220kV ICTs and Line/ Bus

reactors except lines Sikar-1/ Jaipur South-

2/ Bhiwadi-1/ Auraiya-1 in service

220kV System: All lines except 220kV Firozabad are in

service

Description of Fault

3

At 133312hrs on dated 07.10.2019, the Yph LA of 400kV

Agra (PG)- Agra (UPPCL) line failed at PG end

The distance protection on detection of a LG fault (FC:

41kA), attempted auto reclose after 01 second

However, the line subsequently tripped on persistent Yph

to Earth fault (FC:52kA) and both Main & Tie CB of the line

got opened at Agra end @133313hrs

Description of Fault...Continued

4

At the first instant of Y-N fault in the line, North East Agra

HVDC Pole -3 also tripped on converter differential

protection @133312hrs

Description of FaultLine Y-N fault@133312hrs

5

Description of FaultAR attempt on persistent fault@133313hrs

6

Description of FaultPole-3 tripping

7

The Pole-1, 2, 3 & 4 i.e. all poles were running in normal

direction:

600 MW from BNC to Agra &

700MW from APD to Agra

Tripped on converter differential protection @133312hrs

The tripping of Pole-3 caused no loss of transmission

power (active power compensation)

Analysis of Fault400kV Agra- Agra line

8

There was a failure of Yph LA at Agra end of line

The protection system on detection of fault tripped only Yph

Main & Tie CBs for isolating the fault

Carrier to other end for aiding in tripping of remote end CB

After dead time of 01 sec, the auto reclose close was given to

only the Main CB from BCU

The Yph CB closed on to fault that was persisting due to LA

failure which led to 3phase tripping of both Main & Tie CBs

Analysis of FaultNEA Pole-3

9

• Due to AC grid disturbance AC bus voltage decreased causingdetection of commutation failure in all poles at Agra end

• Commutation failure causes increase in DC line current, which wasmeasured correctly on secondary side by DC CT of all poles exceptPole-3 system A

• This caused converter differential protection of System A to operate& trip pole-3

Analysis of FaultNEA Pole-3 Sys A TFR

10

Analysis of FaultNEA Pole-3 Sys B TFR

11

Action taken for restorationLine

12

• The failed LA was replaced by a new one• The failure of LA had caused damage to nearby BPI,wave trap support insulators also

• All such damages rectified/ replaced• The line was taken back into service @0040hrs on08.10.2019

Failed LAReplacement

13

Failed LA can be seen lying on the ground.

Erection of new LA in progress.

Action taken for restorationNEA Pole-3

14

• The converter differential protection operated fromonly System A

• On clear identification of the issue with Zero flux DCCT measurement by observing the events/TFRs of

all other poles, the NEA pole-3 was taken back into

service at 1408hrs

Proactive actions taken to avoid similar event in future

NEA Pole-3

15

• The Issue of wrong measurement of DC current byDC CT of Pole-3 System A was been taken up with

OEM

• Based on their findings new hardware and software

revision has been done as per Revision order No.

RO-646 (HITECC status connection need to change to

avoid disturbance) in all the poles

THANKS

16

30-01-2020

1

27/11/2019: Uri-I & II

Transient Fault was in Y-phase

Uri-II- Wagoora Line

Y-Phopen

Y-Phre-

close

30-01-2020

2

Uri-I to Uri-II Line

Uri-I End

Uri-II End

Analysis:Uri-II-Wagoora Line

• Fault was in Y-phase.

• Auto-reclose successful.

• But Tripped from other end in 400 ms.

• Carrier intertripping may be unsuccessful.

30-01-2020

3

Analysis:Uri-II-Uri-I Line

• Fault seen by Uri-I end relay in Zone-I (Y-ph).

• Instead of only Y-ph, both Y & B phase got opened.

• All the Power from Uri-II PS flown through single causing transformer neutral O/C & tripped the units.

Remedial action planed

• DPR at Uri-I end shall be tested.

• Carrier communication and its scheme shall be checked for Uri-II to Wagoora Line.

• GPS time synchronisation at Uri-II shall be checked.

1/30/2020

1

Multiple Element Tripping 30.11.2019 at 15:05Hrs

220kV Substation BBMB Samaypur PCC39_Agenda A.8. (Sr. No. 20)

Brief Event Summary

• On 30.11.19 / 15:04 Hrs , there was Yellow phase fault on 220kV Samaypur-FGGP-1.

• At 15:04:10:30, any Trip B became On due to Y- ph fault on FGPP Ckt-1 at 2.292 Km.

• Trip command to Y-pole extended. Y- Pole open but fault current of about 36kA could not be interrupted.

• LBB of FGPP -1 operated after 200ms of any trip command from D.P. Scheme of FGPP Ckt-1 and feeders connected on Bus-1 tripped through 96 trip relays.

• Simultaneously, Y- pole C.B. of FGPP -1 failed / damaged.

1/30/2020

2

Antecedent Condition Weather: Clear

Power flow, shutdowns etc:No Shutdown

Change in Frequency

1/30/2020

3

Change in Voltage – PMU data Plot Generation Loss/Load Loss

Generation Loss: Nil

Load Loss: 200MW

Load running before tripping (as per substation log sheet):

220kV Ballabgarh-2 (48MW),

220kV Ballabgarh – 3 (40MW),

220kV FGGP- 1 (23MW),

220kV Palli – 2 (53MW),

ICT Bank-1 (LV Side-38MW),

Bank-2 (LV Side-38MW) ),

ICT Bank-4 (LV Side- 37MW),

220kV Badshpur-2 (23MW),

220kV Palwal – 1 (103MW).

1/30/2020

4

SLD of Feeders connected on Bus

Ballabgarh-2, FGGP-1, Ballabgarh-3, ICT Bank-1, 2, 4 , Badshapur-2, Palwal-1 connected on Bus-1

1/30/2020

5

Tripped elements connected on Bus-11) 30.11.19/ 15.05.29.658 220kV Palwal - 1

2) 30.11.19/ 15.05.29.659 220kV FGPP – 1

3) 30.11.19/ 15.05.29.662 ICT Bank-1

4) 30.11.19/ 15.05.29.663 220kV Ballabgarh -3

5) 30.11.19/ 15.05.29.666 220kV Ballabgarh - 3

6) 30.11.19/ 15.05.29.666 220kV Bus Coupler-2

7) 30.11.19/ 15.05.29.668 220kV Badshpur-2

8) 30.11.19/ 15.05.29.689 220kV Palli-2

9) 30.11.19/ 15.05.29. 815 220kV Bus Coupler-1

10) 30.11.19/ 15.05.29. ICT Bank- 2

11)30.11.19/ 15.05.29. ICT Bank - 4

SCADA SOE

1/30/2020

6

Location and Type of Fault

Yellow pole currentinterrupter chamberdamaged. FGPP-1 wasconnected on Bus-1

Flag Details, DR and ELD.P. R. MiCOM P444 Indications

1/30/2020

7

Event Description – D.P.R. MiCOM P444 • 15:04:10.430: Any Int. Trip ON

• 15:04:10.430: DIST Sig. Send ON

• 15:04:10.430: DIST Trip B ON

• 15:04:10.430: Any Trip ON

• 15:04:10.430: Any Trip B ON

• 15:04:10.432: Any Pole Dead ON

• 15:04:10.651: All Pole Dead ON

• 15:04:10.676: Any Trip OFF

LBB - MiCOM P442 Indications

1/30/2020

8

Appropriate Graphical Plot DR - MiCOM P444 -DPR

Y-Pole open

IB Fault current 42795.8A at 15:04:10:408308

Any Trip B

DR LBB MiCOM P442 – FGPP-1

L2 Y-PH INI tBF1 Trip

IB 39574 A

1/30/2020

9

Description/ Analysis of the Event Description

• 30.11.19 / 15:04 Hrs , Yellow phase fault was on 220kV Samaypur-FGGP-1.

• 15:04:10:30, any Trip B: On due to Y- ph fault on FGPP Ckt-1 at 2.292 Km.

• Operation of MiCOM P444 of FGPP-1 was in order and trip command to Y-pole was extended.

• Y- Pole opened but fault current of about 36 kA could not interrupted after opening of Circuit Breaker.

• LBB of FGPP -1 operated after 200ms of any trip command from D.P. Scheme of FGPP Ckt-1

• Feeders connected on Bus-1 tripped through 96 trip relays.

• Simultaneously, Y- pole C.B. of FGPP -1 damaged.

• Other end tripped in Zone-2.

• Behavior of protection system was in order.

Restoration

1/30/2020

10

Equipment failure / Reason of Failure / Remedial Action

• Y-Pole interrupter chamber of 245kV SF-6 ABB make Circuit Breaker. Year of manufacturing – 1988. Year of commissioning: 1999.

• Y-Phase 198kV CGL make L.A. Year of manufacturing & commissioning: 1998 & 1999.

• Overhauling of C.B. in 2015 (only drive mechanism).

• Breaker operating time and CRM were normal during last

periodical testing on 16.05.19.

• No abnormality was observed in the breaker before failure.

• Exact reason of damage of pole could not be ascertained.

Breaker Test Results

1/30/2020

11

Y-Pole Damaged Adjacent Pole Collars damaged

1/30/2020

12

LA damaged Any other Information - Reason of Connecting three ICTs on Bus-I

• Male & Female contact assembly along with arm of Y-phase 220kV Bus 2A isolator of ICT-4 got damaged in past. Spare isolator arm and male / female assembly are being arranged and will be replaced shortly.

• Bus-II isolator of ICT-1 & 2 has hot points on female & male contacts. Male and Female jaw assembly is being arranged and will be replaced shortly.

1/30/2020

13

THANKS

6" I - Northern Regional Power Committee

Documents

Transcript of 6" I - Northern Regional Power Committee