GSM BASED REMOTE FAULT INDICATOR FOR

DISTRIBUTION LINE RELIABILITY IMPROVEMENT

BY: ALEMU ZELEKE BURUSSA

A Thesis Submitted to:

The department of Electrical power and control Engineering

School of Electrical Engineering and computing

Presented in Partial Fulfillment of the Requirement for the Degree of

Master’s in Electrical Engineering

(Specialization in Electrical power)

Office of graduate studies

Adama Science and Technology University

July, 2020 G.C

ADAMA, ETHIOPIA

GSM BASED REMOTE FAULT INDICATOR FOR

DISTRIBUTION LINE RELIABILITY IMPROVEMENT

By: ALEMU ZELEKE BURUSSA

Advisor: Dr. Tefera T.Y

A Thesis Submitted to:

The department of Electrical power and control Engineering

School of Electrical Engineering and computing

Presented in Partial Fulfillment of the Requirement for the Degree

Of Master’s in Electrical Engineering

(Specialization in Electrical power)

July, 2020 G.C

ADAMA, ETHIOPIA

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Approval of Board of Examiners

We, the undersigned, members of the Board of Examiners of the final open defense by Alemu

Zeleke have read and evaluated his thesis entitled “GSM based remote fault indicator for

distribution line reliability improvement” and examined the candidate. This is, therefore, to

certify that the thesis has been accepted in partial fulfillment of the requirement of the Degree

of Master’s in Electrical power Engineering.

Name Signature Date

_____________________________ _____________________ ___________________

Name of student

_____________________________ _____________________ ___________________

Advisor

_____________________________ _____________________ ___________________

External Examiner

_____________________________ _____________________ ___________________

Internal Examiner

_____________________________ _____________________ ___________________

Chairperson

_____________________________ _____________________ ___________________

Head of department

_____________________________ _____________________ ___________________

School Dean

_____________________________ _____________________ ___________________

Post graduate Dean

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Declaration I hereby declare that this MSc Thesis is my original work and has not been presented for a

degree in any other university, and all sources of material used for this thesis have been duly

acknowledged.

Name: Alemu Zeleke

Signature:_________________________________________________________________

This MSc Thesis has been submitted for examination with my approval as thesis advisor

Name: Dr.Tefera T.Y

Signature:_________________________________________________________________

Date of submission:……….

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Advisor’s approval sheet To: Electrical power and control engineering department

Subject: Thesis Submission

This is to certify that the thesis entitled “GSM based remote fault indicator for distribution line

reliability improvement’’ submitted in partial fulfillment of the requirements for the degree of

Master’s in Electrical engineering, the Graduate program of the department of Electrical power

and control Engineering, and has been carried out by Alemu Zeleke Id. No A/PE16435/10,

under my supervision. Therefore, I recommend that the student has fulfilled the requirements

and hence hereby he can submit the thesis to the department.

____________________________ _________________________ _________________

Name of Advisor Signature Date

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ACKNOWLEDGEMENT First and foremost, I thank the Almighty God for His guidance throughout my studies in the

University and the completion of this thesis.

I am very grateful to my advisor Dr.Tefera for his guidance throughout this thesis. The

sessions that I had with Dr.Tefera inspired me to work harder every time we met.I also thanks

the Department of Electrical and computer Engineering and my lecturers for instilling in me

the knowledge that has brought me this far.

Finally, I am grateful to all my classmates and friends who contributed to the success of my

studies in one way or another. I specifically thank Mr. Hayilemikael Mindaye(MSC), for his

invaluable support in material and knowledge and for being so great friends and brothers

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Table of Contents

CONTENTS PAGE

ACKNOWLEDGEMENT .............................................................................................................................. iv

List of table ............................................................................................................................................... vii

List of figure ............................................................................................................................................ viii

Abbreviation ..............................................................................................................................................ix

Abstract .....................................................................................................................................................xi

CHAPTER ONE ............................................................................................................................................ 1

Introduction ........................................................................................................................................... 1

1.1 Background of the study .............................................................................................................. 1

1.2 Problem statement ....................................................................................................................... 2

1.3 objective of the research .............................................................................................................. 2

1.4. Methodology .............................................................................................................................. 3

1.5 Significance of the study ............................................................................................................. 3

1.6 Thesis organization outline.......................................................................................................... 4

CHAPTER TWO ........................................................................................................................................... 5

Literature review and theoretical background ....................................................................................... 5

2.1 Literature review ......................................................................................................................... 5

2.2 Theoretical background ............................................................................................................... 8

2.3 Faults in the distribution line ....................................................................................................... 8

2.4 common distribution system faults .............................................................................................. 9

2.5 Effects of power system faults .................................................................................................. 14

2.6 Distribution system reliability ................................................................................................... 14

2.7 Distribution system fault detection and protection .................................................................... 16

CHAPTER THREE ................................................................................................................................. 19

Evaluations and Analysis of the Existing System ............................................................................... 19

3.1. Introduction .............................................................................................................................. 19

3.3. Data collection .......................................................................................................................... 22

3.4 Causes of power interruptions ................................................................................................... 25

3.5. Types of fault recorded in Assela substation ............................................................................ 26

3.6. Reliability Evaluation and Analysis Methods .......................................................................... 29

3.7. Data Analysis ........................................................................................................................... 30

3.8 Summary of the Result of Data Analysis for Existing Gumguma Feeder Line ........................ 33

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3.9. Bench Marking for Distribution System Reliability Indices .................................................... 34

3.10. Reliability cost and worth ....................................................................................................... 35

CHAPTER FOUR ................................................................................................................................... 38

Proposed Solution for (GSM based) improving reliability of distribution line ................................... 38

4.1 System Hardware ...................................................................................................................... 39

4.2 Mode of operation. .................................................................................................................... 40

4.3 Modeling Distribution Network fault location and Reliability improvement ........................... 43

4.4 Modeling and assessment technique ......................................................................................... 43

4.5 Comparisons of distribution line with and without FI ............................................................... 45

CHAPTER FIVE .......................................................................................................................................... 46

Results and Discussions ...................................................................................................................... 46

5.1 Introduction ............................................................................................................................... 46

5.2 Case-1 Placement of the three recloser in Feeder Line ............................................................. 48

5.3 Case-2 Placement of the six recloser in Feeder Line ................................................................. 50

5.4 Case-3 Placement of the seven recloses in Feeder Line ............................................................ 51

5.5 Simulation and result ................................................................................................................. 53

CHAPTER SIX ....................................................................................................................................... 63

Conclusion and Recommendation ....................................................................................................... 63

6.1. Conclusion ................................................................................................................................ 63

6.2 Recommendation ....................................................................................................................... 64

Reference ................................................................................................................................................ 65

APPENDIX ................................................................................................................................................ 68

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List of table Table 3.1 distribution line data for Assela feeder gumguma line……………………………...23

Table 3.2 Transformer data with its load rating of Assela gumguma line……….....................24

Table 3.3a Assela substation interruption total frequency from 2009-2011 e.c………………25

Table 3.3b Assela substation interruption total duration from 2009-2011 e.c………………...25

Table 3.4 Reliability indices for existing system……………………………………………...33

Table 3.5 International comparison of reliability indices……………………………………..35

Table 5.1 relation of switch ENS, SAIDI and max. Profit……………………………………48

Table 5.2 Result of reliability indices for case 1……………………………………………...51

Table 5.3 Result of reliability indices for case 2……………………………………………...52

Table 5.4 Result of reliability indices for case 3……………………………………………...54

Table 5.5 Result of each line under normal condition………………………………………..56

Table 5.6 Result of each line under normal condition………………………………………...57

Table 5.7 Summary of result displayed in each case………………………………………….62

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List of figure

Figure 2.1 single line to ground fault with fault impedance……………………………….......11

Figure 2.2 sequence network connection for single phase to ground…..……….……………..11

Figure2.3 phase to phase to ground fault with fault resistance and ground resistance……..….12

Figure 2.4 phase to phase fault with fault resistance….……………………………….………13

Figure 2.5 three phase short circuit and ground fault with ground resistance………………....14

Figure 3.1topography of Assela town…………………………………………………………20

Figure3.2 Assela substation…………………………………………………………………...21

Figure3.3 Assela distribution network…………………………………………………….......22

Figure 3.4 percentage of recorded fault in Assela substation Gumguma feeder line.................29

Figure 3.5 single line diagram of existing system…………………………………………......38

Figure 4.1 Block diagram of fault indicator…………………………………………………...41

Figure 4.2 Flow chart of proposed approach…………………………………………………..44

Figure 4.3 A typical distribution system with one FI………………………………………….45

Figure 4.4 Activity time diagram without FI………………….……………………….……....47

Figure 4.5 Activity time diagram with FI………………………………………….…..............47

Figure 5.1 Relation b/n switch cost maximum profit……………………………..……….......50

Figure 5.2 Single line diagram of case 1……………………………………………................51

Figure 5.3 Single line diagram of case 2……………………………………………………....53

Figure 5.4 Single line diagram of case 3……………………………………………................54

Figure 5.5Relation of fault indicator and SAIDI……………………………………………....55

Figure 5.6 Schematic diagram of proposed system/control station…………………………....56

Figure 5.7 Schematic diagram of proposed system/line station……………………………….57

Figure 5.8 Schematic diagram of proposed system under normal condition …………… …...57

Figure 5.9 Schematic diagram when ground fault occurs on line-1…………………...............58

Figure 5.10 Schematic diagram when short occur b/n line-1 and line-2……………………....57

Figure 5.11 Schematic diagram when ground fault occurs on line-3………..………………...58

Figure 5.12 the operation of auto recloser/relay during fault occur…………………………...60

Figure 5.13 the operation of auto recloser/relay under normal condition…………………..…61

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Abbreviation

ADC Analog to Digital Conversion

CAIDI Customer Average Interruption Index

CT Current Transformer

DA Distribution Automation

DS Distribution System

DN Distribution Network

DPEF Distribution Permanent Earth Fault

DPSC Distribution Permanent short Circuit Fault

DTEF Distribution Temporary Earth Fault

DTSC Distribution Temporary short Circuit Fault

DLOL Distribution Line Overload

EMS Energy Management System

EPRI Electrical Power Research Institute

EENS Expected Energy not Supplied Index

EEPROM Electrically Erasable Program Read Only Memory

ETAP Electrical Transient Analyzing Program

FI Fault Indicator

FLISR Fault Location Isolation and Service Restoration

GPS Global Positioning System

GSM Global system for mobile communication

ICT Information and Communication Technology

IEC International Electro technical Commission

IED Intelligent Electronics Devices

IEEE Institute of Electrical and Electronics Engineering

KM Kilo-Meter

KV Kilo-Volt

KVA Kilo Volt Ampere

KWh Kilo Watt hour

LV Low Voltage

MTTR Mean Time To Repair

MV Medium Voltage

RAM Random Access Memory

SCI Serial Communication Interface

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SIM Subscriber Identity Module

O/C Over Current

PT Potential Transformers

PTOL Power Transformer Overload

OP Operational Interruption

SAIDI System Average Interruption Duration Index

SAIFI System Average Interruption Frequency Index

SM Smart Grid

SOL System Over Load

TLP Transmission Line Fault

VT Voltage Transformer

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Abstract The paper presents development of distribution system GSM based fault detection and location

to decrease power outage and improve reliability of the system. Assela distribution system is

taken as case study to demonstrate the effectiveness of the proposed technique. It is found that

the three (3) year primary and secondary data is collected, analyzed and the result shows that

55.4% of the total hours and 52.95% of the total frequency is related to distribution related

problem.

The proposed distribution system fault detection and location is capable of detecting feeder

faults, fault location, isolation the faulty section of the feeder and finally reporting the faulted

area to the authorities or operator. Thus it has the capacity to significantly improve the

reliability of the distribution system by decreasing frequency of fault, decrease time for the

technical crew and decrease number of interrupted customer.

If the measured electrical quantity or parameter are above or below preset value then the

system automatically operate the auto recloser. Where as in another direction it will detect the

location of fault occurred by comparing voltage and current magnitude which insure shorter

response time for the technical crew to search this faults and helps in saving the system from

damage and long period energy waste.

The system have a master unit at the control station or at substation and line unit at each node

which have a current transformer , voltage transformer , Arduino microcontroller, RS 232

connector ,a GSM module and auto recloser switch .

The performance of the proposed model is tested with the simulation to check the reliability

improvements of Assela distribution gumguma feeder network. The result shows SAIDI and

SAIFI is improved by 62.084% and 64.2036%.

Key: GSM, microcontroller, fault detection, feeder network, fault location

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CHAPTER ONE

Introduction

1.1 Background of the study Due emerging developments in all sectors growing demands, electricity has become priority

for every individual and every organization. Basically, the power supply includes generation,

transmission, distribution and finally utilization at the end. Losses in the distribution side are

much higher than losses in the transmission side and also faults are more frequent in

distribution side. In distribution system most of the losses are caused by fault and theft [3].

Electrical power interruption/fault becomes a day today phenomenon. Even there are times

that electrical power interruption become occurs several times a day. And this makes the

power system unreliable.

In this thesis the focus is detecting and locating fault in power distribution line. When fault

occurs in a distributions line it becomes significant to detect and locate fault quickly. In

general there are two methods to improve network. The first method is to reduce the

frequency of interruption and the second is to reduce the outage duration while the fault

occurs. Installation of fault indicator (FI) in the primary feeders of distribution network is

one way to decrease the outage duration. This thesis is to provide with a simple way to

detect the fault and show the location of occurred fault which will ultimately lead to

optimum operation of the whole system and to improve the reliability of distribution

network.

In this concept electric distribution network is in to pieces of wireless sensor node which

will constantly interact with primary node which will be in control room. Each sensor node

contain of three components current and voltage sensor, microcontroller and GSM modem.

To reduce the duration of outages frequency and minimize the response time to major faults,

and to optimize a reliability of supply. It is helpful for power distribution companies to

search for low cost communicating devices with low power consumption that will transmit

accurate fault information at real time back to the control center.

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1.2 Problem statement In Assela Distribution system, Electrical power interruption becomes highly pronounced

phenomenon. Even there are times that electrical power interruption occurs several times a

day because of different factors, such as: Faults, overload, protection failure, aging

infrastructure, maintenance and operation practice, high expose to environment condition,

and human operational error have cause the electrical power distribution system to be

addressed as the main contribution to customer reliability problem that result in sustain

interruption.

Assela distribution network is radial and manually operated system. The maintenance

personnel have to perform fault management activities based on the customer and substation

operator’s outage calls, based on receiving trouble call, the utility/service center will then

dispatch a maintenance crew. The crew will at first locate the fault location in the

distribution line through visual tracing or try and error testing and then implement the

manual switching scheme to conduct fault isolation and power restoration. The maintenance

crew fined the fault location from substation to each end of the branched distribution line.

This is too tedious for the crew and time consuming especially when the line moves through

rural areas where there is no access to road and move through forest and also cross different

woredas as they which may responsible to maintain the distribution line. Therefore when

there is no power for long duration the consumer may directly or indirectly face for different

social and economic problem.

1.3 Objective of the research

1.3.1 General Objective The main objective of this research is to study and evaluate location of faults in the

distribution line. These enhance the distribution reliability improvement and satisfy the

customer by reducing outage impact, duration and frequency of power interruption.

1.3.2 Specific objective To design an efficient GSM based fault detection and location

To propose how to increase the government income

To develop user interface for practical fault locator implementation

To design ways how to reduce interruption

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1.4. Methodology The following methods are applied to perform this thesis

The study has been reviewed helpful literature which is mainly concerned on

number of journals, conference paper, article and papers on power distribution

system reliability assessment and study, feeder reconfiguration, FLI technology and

other related works.

Primary data collection like feeder length, number and ratings of transformers and

Load of the system has been collected from the existing system of Assela feeder

Gumguma line though site visit.

Secondary data like three years (2009-2011E.C.) interruption data has been collected

from Assela substation.

The data obtained from different categories of concerned bodies has been organized

to make it available for reliability analysis.

Assela feeder Gumguma line is represented using single line diagram.

Improved network topology reconfiguration with protection system has been

developed that is the thesis suggests the division of the DN in to manageable

area/zone and application of FL technology for protection of each zone has been

applied.

Reliability indices have been calculated for the existing selected feeder and the

modified systems.

Based on the result of this analysis and assessment, reconfigured network with

additional FL technology have been evaluated for potential reliability improvement.

The simulation has been made in ETAP16 software to evaluate the distribution

reliability performance and proteus software is used to simulate the location of fault

occurred which reduce the time of restoration of supply.

1.5 Significance of the study The study tries to find the reason that lead to fault location and use the result of study for

improving a distribution line reliability .According to the obtained data the line has 66

different rating transformers which serves health center, industry, consumers and supplies a

maximum power of 4MVA. This shows that the study attempts to give attention to the

problem of a considerable part which indicates its magnitude of significance.

In addition to this, the study may help other researchers to give clue to similar problem that

can arise their interest and effort in finding the proposed solutions.

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1.6 Thesis organization outline Chapter 1: This chapter gives an introduction to the power system faults, problem of

statements and an overview of the solution to address the problem as well as the main

objective and the specific objectives of the research is described.

Chapter 2: It describes collection of different literatures review from previous similar works.

Fault location in distribution systems in different techniques. Also describes about the power

system faults mainly distribution systems faults, distribution system protections and different

type of shunt faults and the fault conditions of the faults are described. And also the brief

overview of the reliability of power system.

Chapter 3: Existing system primary and secondary data collection, data analysis and draw

conclusion from the obtained result.

Chapter 4: proposed solution to improve the performance of the distribution line.

Chapter 5: Result discussion and Simulation.

Chapter 6: Describes the conclusion and recommendation of the thesis.

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CHAPTER TWO

Literature review and theoretical background

2.1 Literature review

2.1.1 Introduction A fault in the distribution system is located through conventional approaches, such as upon

receiving a complaint from a customer, a technical staff is deployed to find the fault by

patrolling the suspected faulted feeder. Meanwhile, for an underground cable system,

switching operations were widely practiced to identify the faulted section. Thus, the locating

process is time consuming and might expose additional stress to the equipment during the

switching on/off of a section. This conventional fault detection relay on visual inspections of

the faulted line parts resulting in long and tedious foot or aerial patrols. These methods were

expensive and prone to more errors. Due to these problems, many automated fault location

methods have been introduced by researches to expedite the process of locating faults. Some

of the fault detection methods are selected from technical journal paper of previous similar

works is reviewed in this section.

2.1.2 Impedance Based Method In impedance based fault location methods is using impedance as seen from a monitored

node to estimate the location of fault from measurement of voltage or current at the

monitored substation [10]. Based on Ohms Law, voltage and current from the monitoring

node can be used to determine fault [5]. The simple formulation of fault location solution

with absolute values is [45]:

lZI

Vd

* (2.1)

where: V ,voltage during the fault in Volt, I , current during the fault in Ampere, Zl, line

impedance in ohms per length unit, d ,distance to the fault in length unit such as miles.

The advantage of impedance based method is that it is cheaper compared to traveling wave

method as it only requires measurement data of the distribution line. As a result, the

accuracy of the method is based on the data taken from the system [14].Some improvement

to the impedance based fault location is made considering the capacitive effect of the power

distribution line [12]. The obtained result shows the capacitive effect Fault location

estimator design for power distribution system should not be neglected in the distribution

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system fault location with impedance based. In this method is good for less complex

distribution network and the limitations with this method is as the complexity of distribution

systems increase and various uncertainty factors such as length of conductors, type of

conductor and cables and unknown fault resistance makes it difficult to address using

impedance-based method fault location [5].

2.1.3 Technique based on travelling wave phenomenon The travelling wave technique which is based on the reflection and transmission of the

generated travelling waves along the faulty power networks [10]. Traveling wave based fault

location in distribution line or transmission line fault at any point on voltage wave

propagates step wave toward both the source and load direction. One method of determining

the fault location is precise time measurement of traveling wave arrival at both ends.

Traveling wave uses naturally occurring surges and waves occurred by faults. The fault

distance (df) can be calculated using the following expression [14]:

2

)(* 12 ttVd f

(2.2)

Where: V, the velocity of the traveling wave, 𝑡1 time when waveform started to travel, 𝑡2

time when waveform arrived at the record node. The limitation with this method is single

end line recorder and spreaded recorders along with the distribution line are used and it is

costly for practical implementation. The proposed technique extracts the fault initiated high

frequency components of the voltage signals, which are recorded only at the substation, by

using wavelet transformation technique. The fault location procedure described here

assumes that voltage measurements are available only at the sending end [21]. The

advantage of this approach is its insensitivity to naturally occurring in feed from the

distributed generators during a fault. But sometimes in feed is typically unpredictable and

makes the traveling wave based fault location methods vulnerable to errors.

2.1.4 Knowledge based fault location techniques Uncertainty of line parameter affecting variables, such as length of cables and unknown fault

resistance, coupled with the complex structure of distribution management systems tends to

make fault location through impedance and travelling wave techniques inaccurate. As a

result of this, knowledge-based technique for locating faults has receiving attention from

researchers in the last few years. In general, the technique requires information such as

substation and distribution switch status, line measurements, atmospheric conditions, and

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information provided by fault detection devices installed along the distribution feeders. This

information is analyzed using artificial intelligence methods to locate a fault.

2.1.4.1. Fuzzy logic.

In some electric power systems, the conventional algorithm is not suitable to produce the

information and location for the maintenance operation. It will be more appropriate to

implement the fuzzy-based approached as mentioned in [14]. This method concept is to

produce numbers of fuzzy rules for each type of fault available. This not only enables the

system to detect and locate the fault but also identifies the type of fault that occurred. The

advantages of fuzzy-based approach are that it is flexible in the aspect of the input value and

measurement accuracy. This is because the measurement accuracy depends on the rules

determined in the designing process of the fuzzy logic system. The more solid the

membership function of the fuzzy logic system, the more accurate the system. In the

situation where the measurement is inaccurate, the fuzzy sets provide more information as a

single input can use multiple membership degrees to be used in the calculation for a higher

accuracy. One of an example of a fuzzy logic application with solid membership function

was simulated in [14] where the system is capable of detecting and classifying all types of

shunt faults accurately. Other than that, the system is immune to the variation in resistance

of the fault, interception angle and location of the fault.

2.1.4.2 Neural network. System fault is the greatest threat to the electrical power system, especially in electrical

supply. This is because faults consist of many types and are unavoidable. Therefore, a

system that can detect and classified the fault occurrence is needed to protect the equipment

in the electric power system. Due to an increasingly sophisticated electric power system, the

procedure to deal with fault and the possibility of detecting a fault is the system becomes

more complicated. Therefore, artificial neural network is one of the solutions to solve the

protection issues as it can be trained especially with the ability to train with off-line data

[24].To detect fault location, the artificial neural network needs to be trained with

parameters or input such as voltage phase (𝑉) and the angle (∅) from the measurement node.

Similar to other fault detection and location method artificial neural network also use two

approaches in finding the fault location in the transmission/distribution line which is the one-

end measurement and two-end measurement. Other than detecting the fault location in the

transmission line, the artificial neural network also applied in the location or detection of

high impedance fault in the distribution system. The drawback of the application of artificial

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neural network in fault locating is that designing the system is time to consume as the system

needed to be trained using large size of data to ensure an accurate output of the system.

However, it is proven that the result of simulation of fault detection using the artificial neural

network is reliable as the system's operating time is 13ms after fault occurrence [23].

To summarize this section a number of literatures on different fault location methods are

reviewed. But impedance based fault location is presented in this method is good for less

complex distribution and it is less cost and it can be easily applied than other type of

methods [1].

2.2 Theoretical background

2.2.1 Introduction A fault is any abnormal condition in a power system. The steady state operating mode of a

power system is balanced 3-phase a.c. However, due to sudden external or internal changes

in the system, this condition is disrupted. When the insulation of the system fails at one or

more points or a conducting object comes into contact with a live point, a short circuit or a

fault occurs. This chapter generally describes a typical distribution system and reviews the

shunt faults in power distribution system. This will help us in the data collection from the

simulation of distribution network in different conditions for different type of faults in

distribution system.

2.2.2 Typical distribution system Distribution networks of an electric power system link bulk sources of energy to customers'

facilities. If an outage occurs on a distribution circuit, supply to the customers is interrupted.

It is estimated that 70- 80% of all interruptions occur due to failures in distribution systems

as mentioned in documents [10], [11], [14]. A typical distribution system which includes

sub-transmission circuits, substations, feeders, transformers. At the High Voltage/Medium

Voltage (HV/MV) substations, voltages are stepped down to lower levels of, 33kV, 15kV

and 0.400kV secondary circuits and services to customers' facilities. Distribution substation

may include distribution transformers, buses, reactors, capacitors, circuit breakers, isolators

and recloser. The distribution transformers steps down the voltages from the medium voltage

levels to lower levels for local distribution.

2.3 Faults in the distribution line The distribution system fault causes in Ethiopia contain external factors, natural factors and

some of the improper maintenance factors. The external factors caused fault is high all over

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the year. It can be found that fault causes are affected by the seasons apparently. The fault

number in summer is much more than other seasons for the terrible weather, such as

lightning and high wind

Causes of power system faults

The causes of faults are numerous [04], e.g.

Lightning

Heavy winds

Trees falling across lines

Vehicles colliding with towers or poles

Birds shorting lines

Aircraft colliding with lines

Small animals entering switchgear

Line breaks due to excessive loading

2.4 common distribution system faults There are two types faults occur in the system.

2.4.1 Transient fault A transient fault is no longer present if power is disconnected for a short time and then

restored. Many faults in overhead power lines are transient in nature and power system

protection devices operate to isolate the area of the fault, clear the fault and then the power-

line can be returned to service. Typical examples of transient faults include:

momentary tree, bird or animal contact

lightning strike

conductor clashes

2.4.2 Permanent fault A permanent fault can cause lasting damage to the transmission/distribution lines. To

counter a permanent fault, the line first has to be isolated and then correction has to be made

to the line. Some examples of the fault of permanent nature are:

direct lightning stroke on line

man-made damage

mechanical damage due to environment and age

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Permanent faults can be divided in to two categories; these are open circuit and short

circuit

2.4.2a) open/series circuit fault These types of faults are also called Ferro-resonance [34].Series faults which represent open

conductor and take place when unbalanced series impedance conditions of the lines are

present. In the real world a series faults takes place, for example, when circuit breakers

controls the lines and do not open all three phases, in this case, one or two phases of the line

may be open while the other/s is closed. Series faults are characterized by increase of voltage

and frequency and fall in current in the faulted phases.

2.4.2b) short circuit/shunt circuit fault Shunt Faults are the most common type of fault taking place in the field. They involve

power conductors or conductor-to-ground or short circuits between conductors. One of the

most important characteristics of shunt faults is the increment the current suffers and fall in

voltage and frequency

It includes conventional shunt faults like:

Single line-to-ground fault

Line-to-line fault

Double line-to-ground fault

Balanced 3- phase-to-ground fault

Experience has shown that 95 percent of faults are single phase to ground fault [34]. All

faults, except the three-phase faults causes power systems to operate in unbalanced modes.

(a) Single-phase-to-ground faults

The following three types of single-phase-to-ground faults are experienced

(a) Phase A-to-ground faults.

(b) Phase B-to-ground faults.

(c) Phase C-to-ground faults.

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GND1

Zf BAZf

GND2 GND3

Zf

C

(a) (b) (c)

Figure 2-1 single phase to ground fault with fault impedance

Consider a single line-to-ground fault from phase A to ground (G) at the general three-phase

bus shown in Figure 2-1 (a). For generality, we include fault impedance Zf. In the case of a

bolted fault Zf = 0. Fault conditions in phase domain Single line-to-ground fault of phase A:

afacb IZVandII 0 (2.3)

Using the sequence transformation matrix fault conditions in sequence domain Single line-

to-ground fault of phase A,

1210210210 3)( IZIIIZVVVandIII ff (2.4)

Where 𝐼0, 𝐼1, I2𝑎𝑛𝑑𝑉0, 𝑉1, V2 zero, positive and negative sequence current and voltage

respectively.

Equation (2.2) can be satisfied if interconnection is made in series the sequence networks as

follows: Fault location estimator design for power distribution system

Z1

Z2

Z0

AC

I2

I1

I0

3Zf

V2

V1

V0

Figure 2-2 the sequence network connection for single phase to ground

From the figure the sequence fault current at phase a can be calculated [15]:

Page-12

fa ZZZZ

VaII

3

33

2101 (2.5)

Similarly it can be calculated for other phases,

(b) Two-phase-to-ground faults

Two-phase-to-ground faults are of the following three types.

(a) Phase B and phase C-to-ground faults.

(b) Phase C and phase A-to-ground faults.

(c) Phase A and phase B-to-ground faults.

W1W2 W3

Zf Zf

Zg

Zf Zf

Zg

Zf Zf

Zg

ground ground ground

IcIbIa

Ic Ia

Ig=Ib+IcIg=Ia+Ic Ig=Ia+Ib

Ib

(a) (b) (c)

Figure 2-3 phase to phase to ground fault with fault resistance and ground resistance

Consider a line-to-line-to-ground fault from phase B and C to ground at the general three-

phase bus shown in Figure 2-3 (a). For generality, we include a fault impedance Zf. Fault

conditions in phase domain line-to-line-to-ground fault of phase B and C:

))(2

(0 cbgf

cba IIZZ

VVandI (2.6)

(c) Phase-to-phase faults

The three types of phase-to-phase faults that can be experienced on lines are as follows.

(a) Phase B-to-phase C faults.

(b) Phase C-to-phase A faults.

(c) Phase A-to-phase B faults.

Page-13

Zf Zf Zf

Ib IcIa

Ib IaIc

(a) (b) (c)

Figure 2-4 phase to phase faults with fault resistance

Consider a line-to-line fault from phase B and C to ground at the general three-phase bus

shown in Figure 2-4 (a). For generality, we include a fault impedance Zf. Fault conditions in

phase domain line-to-line fault of phase B and C:

bfcbcba IZVVandIII ,0 (2.7)

(d) Balanced three-phase faults

Three phase faults that have equal fault resistances in the three phases are called balanced

three-phase faults. It occurs infrequently, as for example, when a line, which has been made

safe for maintenance by clamping all the three phases to earth, is accidentally made alive or

when, due to slow fault clearance, an earth fault spreads across to the other two phases or

when a mechanical excavator cuts quickly through a whole cable.

Figure 2-5 all phase to phase and to ground fault with and ground resistance

Page-14

2.5 Effects of power system faults Faults may lead to fire breakout that consequently results into loss of property, loss of life

and destruction of a power system network. Faults also leads to cut of supply in areas

beyond the fault point in a transmission and distribution network leading to power blackouts;

this interferes with industrial and commercial activities that supports economic growth,

interrupt learning activities in institutions, work in offices, domestic applications and creates

insecurity at night. All the above mentioned results into retarded development due to low

gross domestic product realized. It is important therefore to determine the values of system

voltages and currents during faulted conditions, so that protective devices may be set to

detect and minimize the harmful effects of such contingencies.

2.6 Distribution system reliability Distribution reliability primarily means continuation of power supply without interruption.

Simply, reliability is the measurement of equipment outage rates and power interruption

duration [29]. There are various events that disrupt normal operation of the distribution

system leading to power outages. However, some key descriptions pertaining to distribution

system reliability are explained below.

A. Customer Oriented Indices

1. System average interruption frequency indices /SAIFI/ is the average number of times

that a system customer experiences an outage during the year. It is the average frequency of

sustained interruption per customer over a predefined area. This index specifies on how

many times the customer experiences a nonstop interruption with a period of time in their

respective area. In order to obtain an accurate result, the improvement of SAIFI’s index is

the fixed number of customers also reducing the number of the continuous interruptions on

the system [27]. It show the customers at the utility that the probability of experience a

power outage.

NT

NiSAIFI

SAFI

Served Customers ofNumber Total

onsInterrupti Customer of Number Total

(2.8)

NT = Total Number of Customers Served

Ni=Total Number of customer interrupted

Page-15

2. System average interruption duration indices /SAIDI/ is used for performance

measurement of sustained interruption which measures the total duration of an interruption

for the average customer during the given time period. This index is responsible for the

average service interruption in the system. SAIDI’s purpose is to indicate the total duration

of an outage when continuous interruption occurs that result in power loss. [29] It is

commonly referred to as customer minutes of interruption or customer hour and provides

information as to the average time the customer is interrupted.

NT

riNiSAIDI

SAIDI

)(

served customer ofnumber Total

duration oninterrupti Customer

(2.9)

ri=Restoration time minute for each interruption event

NT = Total Number of Customers Served

Ni=Total Number of customer interrupted

3. Customer Average interruption frequency indices /CAIFI/ is gives the average frequency

of sustained interruption for this customer experiencing sustained interruption. It measures

the average number of interruption per customer interrupted per year. It is simply the

number of interruptions that occurred divided by the number of customers affected by the

interruption.

Ni

NoCAIFI

)(

dinterruptecustomer ofNumber Total

oninterrupti of Number Total The CAIFI

(2.10)

No = Number of interruption

4. Customer Average interruption Duration indices /CAIDI/ is once an outage occurs the

average time to restore service is found from the customer average interruption duration

indices. It is the average time needed to restore service to the average customer per

sustained interruption. It is the average interruption duration for those customers interrupted

during a year. It is determined by dividing the sum of all customer interruption durations by

Page-16

the number of customers experiencing one or more interruptions over a one year period [29]

SAIFI

SAIDI

Ni

riNiCAIDI

CAIDI

)(

onInterrupti Customer of number Total

Durationon Interrupti Customer

(2.11)

5. Average Service Availability Index (ASAI): This index represents the fraction of time

(often in percentage) that a customer has power provided during one year or the defined

reporting period.

B. Load or Energy Oriented Indices

1. Expected Energy Not Supplied Index (EENS): This index represents the total energy not

supplied by the system. [37]

HourswattLirii

durationoutageTheoutageduringloadAverageEENS

(2.12)

Where, 𝐿𝑖 is the average load connected to load point i and 𝑟𝑖 is outage duration for event i.

2. Average Energy Not Supplied Index (AENS): This index represents the average energy

not supplied by the system.

3. Average Customer Curtailment Index (ACCI): This index represents the total energy not

supplied per affected customer by the system.

4. Average Load Interruption Frequency Index (ALIFI): This factor is analogous to the

System Average Interruption Frequency Index (SAIFI) and describes the interruptions on the

basis of connected load (kVA) served during the year by the distribution system.

SAIFI, SAIDI and EENS are the most commonly used and known indices to measure

reliability performance of utilities [36].

2.7 Distribution system fault detection and protection The main objective of protection system is to minimize the duration of fault and to protect

power equipment from damage and also increase system performance and reliability.

Distribution systems experience different type of series and shunt faults. The commonly

used equipment for detecting and isolating the faulted circuits in a distribution system are

Page-17

fuses, relays, circuit breakers, and current and voltage transformers. Some of protection

equipment is described below.

2.7.1 Fuses A fuse is an over current protection device used in power system network. Under normal

operating conditions, the heat built up in the fuse element is dissipated to the surrounding air

and thus, the fuse remains at a temperature below its melting point. During fault conditions

such as a short circuit, the heats become very great and cannot be dissipated fast enough.

This causes the fuse element to heat up and melt, thereby breaking the circuit.

2.7.2 Instrument transformers Instrument transformers are transducers used to transform high electric current and voltages

to lower values proportional to the primary magnitudes thereby providing isolation between

the electric power circuit and the measuring instruments. These transducers current

transformers (CTs) and voltage transformers (VTs) measure the current and voltage in a

network and provide low level signals to relays in order to detect abnormal conditions

2.7.3 Relays:-

A protective relay is a device capable of detecting changes in the received signal and if the

magnitude of the received signal is outside a preset range, it operates to initiate appropriate

Fault location estimator design for power distribution system control action in order to

protect the power system. To safeguard the investment in transmission and distribution lines,

several types of protection techniques are used. Earth fault, over-current, differential,

directional, etc are some of these techniques. A single technique or combinations of two or

more techniques are employed to detect faults on transmission and distribution lines. The

digital protective relay is a protective relay that uses a microprocessor to analyze power

system voltages, currents or other process quantities for the purpose of detection of faults in

an electric power system or industrial process system.

2.7.4 Automatic Recloser A recloser is a device with the ability to detect phase and phase to ground over current

conditions, to interrupt the circuit if the overcurrent persists after a predetermined time, and

then to automatically reclose to re‐energize the line. If the fault that originated the operation

still exists, then the recloser will stay open after a preset number of operations, thus isolating

the faulted section from the rest of the system. The majority of faults on a distribution

network can be considered temporary in nature meaning that they do not reoccur if the

power is returned to the network soon after a trip [26]. Automatic reclosing devices are

Page-18

therefore specifically designed to trip and clear transient fault conditions. Automatic recloser

is hydraulically or electrically operated devices that can sense over-current (O/C), earth-fault

(E/F) or sensitive earth-fault (SE/F) conditions. Under these conditions the recloser will,

subject to pre-determined settings, trip and after a time delay reclose automatically. If the

fault is not cleared the recloser will go through a fixed sequence of a trip and reclose cycles

after which it will lockout. The recloser, with its opening/closing characteristic, prevents a

distribution circuit being left out of service for temporary faults. Typically, recloser is

designed to have up to three open close operations and, after these, a final open operation to

lock out the sequence. When the recloser is in the lockout mode the faulted section will be

isolated from the supply and human involvement is required to close the recloser [26]. The

influence of the pole/pad-mounted recloser (circuit recloser) is comparable to the circuit

breaker located at the primary substation. It detects and separates the faulted lines that are

located after the recloser. The operation of the recloser is similar to that of a circuit breaker

when the fault is momentary. This protects the customers before the recloser against the

faults occurring after the recloser. However, a circuit reclose provides a good means to

improve the reliability of the feeder.

Page-19

CHAPTER THREE

Evaluations and Analysis of the Existing System

3.1. Introduction The analysis of the existing system deals with the methodologies used for data collection as

primary and secondary data, in which thesis will be depending on the quality of these data;

the data obtained is organized to utilize it for distribution fault location estimation

implications, analyzes these data and simulate the design procedures for the existing system.

3.2 Background of the study/study area description

Assela is located in the Arsi Zone of the Oromia Region about 175 kilometers from Addis

Ababa through Adama towns which is at the foot of mount chilalo, the second heighst

mountains in the country. Assela is located between 7054’55’’N-8000’05’’N, 39006’10’’E-

39010’00’E. It is a capital of Arsi Zone and Tiyo district of Oromia regional national state. It

retains some administrative functions as the seat of the present Arsi Zone. The 2007 national

census reported a total population for Assela of 67,269.

Figure 3.1 Topography of Assela towns. Source; - (Assela town profiles, 2010)

Page-20

Assela Substation

Assela Substation received electrical power as input from Awash II with the rate of 132KV

transmission line to the two power transformers, The first 25MVA 132/15KV Transformer is

the old one which take as input and take out the five outgoing 15KV feeder lines which are

Etya Line-1, sagure Line-2, Industry Line-3, Assela line -4 and Abura line-5. The second

132/33KV power transformer is the new which installed in the nearest few years which is

not old as the first transformers. It supply electrical power to the other Arisi zone which are

Amude, cochebore, Assela malty Factory and Gumguma with 33kv distribution line which

are Amude line-1, Cochebore Line-2, Assela malty factory line-3 and Gumguma Line-4.

This 33KV feeder lines are extended for rural Arisi Zone towns which is far from Assela

town in order to cover all the rural electrification activities, whereas the towns near to Assela

town areas are feed from old 15KV medium voltage line from the first 132/15KV

transformer. Adami Tulu substation get 132KV Transmission line directly from Assela

substation as input of 132KV which is connected directly from132KV buses of Assela

substation input.

Figure 3.2Assela substation

Page-21

Fro

m A

was

h 2

To A

da

mi T

ulu

su

stat

ion

132/15kv132/33kv/15kv

25MVA 25MVA

15kv bus33kv bus

12.5MVA

132kv bus

1 2 3 4 5

Ass

ela

mal

ty F

Gu

mgu

ma

Am

ud

e

Ko

cho

bo

re

Under constraction

12.5MVA

15kv bus

1

DT

4MVA

4.2M

VA

1MV

A

5MV

A

LV

DT

MV

LV

Figure 3.3 Assela distribution network

Page-22

Case Study

The case study of this thesis is limited to Gumguma line out of the four outgoing line of

33KV distribution line. This line is radial distribution system which delivered electrical

power to the customers of the rural towns from Assela substation in a straight forward

fashion. The distribution lines feed 11 kebeles which have different infrastructure, two

hospitals two water factories. Gumguma Line branches in to various laterals which in turn

separate in to several sub laterals to distribution transformers. The main feeders are before

the distribution transformers are three phase three wires/MV line and low voltage side after

the distribution transformers are three phase four wire or single phase two wire circuit/LV

line.

3.3. Data collection

3.3.1 Primary Data Primary data has been collected by the direct involvement of the researcher and workers of

Assela substation for the purpose that is intended to be done. During the site survey, the

primary data necessary for this study were the length of the feeder, rating and type of each

transformer, topology and layout of the system, conductor type, topography and

environmental conditions.

Line length

One basic parameter for design of the existing system using the software (ETAP 16) is

length of the line. The total length of the feeder has been segmented based on the location of

tap points and transformers. The segments were represented as L1, L2, and L3… L86. The

total length of the feeder was summed up 265.2KM.

Table 3.1 Line Data for Assela Feeder gumguma line

No of Line

Length of feeder [ KM]

Thickness of conductor (mm2)

No of Line

Length of feeder [ KM]

Thickness of conductor (mm2)

No of Line

Length of feeder [ KM]

Thickness of conductor (mm2)

L1 12 95 L30 0.5 95 L59 0.7 95 L2 46 95 L31 7 95 L60 0.5 95 L3 2 95 L32 0.4 95 L61 0.7 95 L4 11.8 95 L33 0.8 95 L62 1.2 95 L5 2.1 50 L34 0.4 95 L63 0.9 95 L6 3.3 50 L35 0.9 95 L64 0.5 95

Page-23

L7 18 50 L36 2.7 95 L65 1.2 95 L8 0.2 50 L37 0.5 95 L66 0.6 50 L9 19 50 L38 2 95 L67 0.5 95 L10 2 50 L39 0.5 95 L68 0.9 95 L11 3 95 L40 0.6 95 L69 0.7 95 L12 5 95 L41 1.2 95 L70 0.8 50 L13 10.7 95 L42 0.5 95 L71 0.5 95 L14 2.9 50 L43 0.8 95 L72 0.9 95 L15 10.7 95 L44 0.9 95 L73 0.9 95 L16 1.5 95 L45 0.5 95 L74 7 95 L17 13 95 L46 1.5 95 L75 0.2 50 L18 2.5 95 L47 0.8 95 L76 4 95 L19 8 95 L48 0.4 95 L77 1.8 50 L20 1.6 95 L49 0.5 95 L78 2 95 L21 4.9 95 L50 0.3 95 L79 0.6 50 L22 0.7 95 L51 0.6 95 L80 5 95 L23 0.3 95 L52 1.1 95 L81 2 50 L24 0.2 95 L53 0.8 95 L82 3 95 L25 0.3 95 L54 1.4 95 L83 7 95 L26 0.5 95 L55 1.3 95 L84 1.2 95 L27 0.8 95 L56 0.5 95 L85 1.5 95 L28 3.5 95 L57 0.1 95 L86 1.3 95 L29 0.5 95 L58 0.6 95 L87

Transformer and Load

The second data required for ETAP 16 for distribution system analysis is transformer ratings

and its caring capacity and the load of the transformer. The total number of transformers

with their total loads is collected for Assela Feeder gumguma line.

Table3.2 Transformer data with its load rating of Assela gumguma line

No of Trans

Rate of Trans

Load kVA

No of Trans

Rate of Trans

Load kVA

No of Trans

Rate of Trans

Load kVA

T1 100 80 T28 50 40 T56 50 40 T2 100 80 T29 50 40 T57 100 80 T3 100 80 T30 50 40 T58 315 252 T4 100 80 T31 50 40 T59 50 40 T5 100 80 T32 100 160 T60 100 80 T6 50 40 T33 200 160 T61 50 40 T7 50 40 T34 200 160 T62 25 20 T8 50 40 T35 315 252 T63 100 80 T9 100 80 T36 50 40 T64 100 80

Page-24

T10 200 160 T37 315 252 T65 200 160 T11 25 20 T38 315 252 T66 100 80 T12 100 80 T39 315 252 T13 200 160 T40 200 160 T14 50 40 T41 200 160 T15 50 40 T42 100 80 T16 50 40 T43 100 80 T17 315 252 T44 315 252 T18 600 480 T45 200 160 T19 800 640 T46 100 80 T20 100 80 T47 600 480 T21 100 80 T48 50 40 T22 100 80 T50 200 160 T23 100 80 T51 200 160 T24 50 40 T52 100 80 T25 200 160 T53 25 20 T26 25 20 T54 315 252 T27 200 160 T55 50 40

3.3.2 Secondary Data The secondary data is collected from Assela substation which is recorded for last three year

from 2009-2011 E.C. of interruption data from 25MVA, 132/33KV transformers four

outgoing 33KV feeder Lines of gumguma line that have a number of frequency and

duration of interruption as recorded below in table (3.3a-b).

Table3.3a Assela substation interruption total frequency from 2009-2011E.C.for each

year from Appendix-A

Feeder Name 2009E.C. 2010E.C. 2011E.C.

Gumguma line 722 753 918

Table3.3b Assela substation interruption total duration from 2009-2011E.C. for each

year from Appendix-A

Feeder Name 2009E.C. 2010E.C. 2011E.C.

Gumguma line 914.53 HRS 964.495 HRS 1197.505 HRS

Page-25

3.4 Causes of power interruptions Assela substation has recorded data of fault type based on frequency and duration of

interruption. The workers records frequency and duration of power interruption and load of

each feeder per hour from the instrument reading and information from utility workers

during total outage. To know the cause of power interruption, the workers of substation

operator can easily identify what type of fault occurred on each distribution line from REF

615 relay installed on the substation control panel and records on the logbook and to know

the location of fault the operator must communicate with service center workers. the cause

of power interruptions are contact of tree, insulation crack some of the pole is steel which

sensitive during rainy season, equipment and wires, tree failing across line , pole failing,

over loading, insulation cracking, animals, large birds., winds, rains and lighting which

cause power interruption in the Assela distribution system and also distribution line are

interrupted for maintenances purposes.

Some cause of the power outage explained by the workers

Steel Poles

From site visit and interview response, the wajiashargie line which is 39.2 km from tapped

munesa branch is all steel pole which is the cause of most faults by cracked insulation during

wet weather condition which the relay shows earth fault and over current fault on the

substation.

Equipment failure

Power distribution system equipment failure results in major customers interrupt in this

section from response of interview, wire become broken and fail to ground, to the arm of the

insulator or to other phase line which form grounding or short circuit accordingly. The other

problem is cracking of insulators in each pole which become crack and make grounding

problems.

Tree

Arsi areas have tree plants which large in number and in size and most length of the feeder

pass near to these trees. The tree near to feeders grow in length of branch or its height which

make contact with phase or make short two or more phases. Or falling trees on feeder line

due to wind or an inappropriate or carelessly terminating of tree by customers interrupt

Page-26

power from the substation by tripping feeder circuit breakers due to tree either making short

circuit or grounding.

During commissioning of new line

Gumguma feeder line is constructed and start operation from June 2008 E.C, so while the

line is trying to energize for the first time most of insulation cracked, the line is tripped due

to wrong connection, and the newly installed transformer insulation fail after it works some

hour.

Animals

Wild animals like Ape, ‘Gureza’ and monkey found in forest. They jump from one tree to

other tree. They make short circuit by tree branch to the line found near to large tree

branches. They also failed on it and they make connection and make short circuits.

3.5. Types of fault recorded in Assela substation 1. Distribution permanent Earth fault

This type of fault is occurred when the feeder line or equipment get in contact with the

grounding directly or indirectly. It is called permanent as it persists from long time after

occurrences. This earthling fault occurs due to tree contact with phase, broken conductor fail

to ground, making contact with other low voltage pole or Tele poles, phase line lose and fail

on the arm of insulator holders, Cracking of insulators and broken insulators by children and

raining and wind make contact with tree.

2. Distribution permanent short circuit fault

Permanent short circuit fault is occurred when two or more different feeder phase lines come

in contact with each other. When this happen, there is excessive current that travels along a

path that is different from the intended one in an electrical circuit, which can lead to circuit

damage, fire and explosion. Short circuit is the most commonly used terms to describe the

cause of power failures.

3. Distribution Temporary Earth Fault (DTEF)

The term DTEF is to indicate that the fault doesn’t persist long. As result it causes circuit

breaker to trip. DTEF occurs during rainy season because of the supporting few steel

structures gets in contact with distribution line and water leak to crack old insulator that

results in interruption. Wind blow forces feeder lines against tree or poles near to lines like

Page-27

Tele poles and low voltage poles. In this feeder, in some areas high voltage lines and

medium voltage lines are condensed in closely placed towers even high voltage line and low

voltage line found up and low in one poles. Possibility of a line getting pushed or pulled to

due to wind exists. Separation between lines gets close and forces of attraction /repulsion are

created. This event produces contact with tree, towers, etc. thereby creating contact to the

earth.

4. Distribution Temporary short circuit (DTSC)

As per interview response DTSC occurs in short time. It doesn’t persist long. Contacts

between distribution lines occur because of windy season, Large birds, Ape, monkey. These

make short two or more phase at the moment directly or indirectly. . The lines contact and

separate causing the breaker to trip. But these contacts do not stay long. It creates

momentary short circuits. Similar event occurs during tree movement by wind and Ape and

monkey jumping creating contact with distribution lines. The tree touches two line same

time forming line to line fault. Moreover, contact of birds dead on lines and stormy rain

season caused interruption.

5. Distribution Line Overload (DLOL)

Increasing demands for electric power have caused existing power grids to become

overloaded. Overloading is a common cause of line voltage fluctuations. Inadequate power

generation and inadequate distribution systems are also causes of line voltage problems.

Improper or poorly designed power regulating devices may create voltage fluctuations.

Loose or corroded connections at the electric service user end can create voltage

irregularities. The same conditions on the distribution power lines may also affect voltage.

Many voltage fluctuation problems can be traced back to inadequate infrastructure.

6. Generation Unit problem/GUP

The power supply include from generation up to utilization. When fault occur across a

Generation unit we cannot get any supply. So that when there is no supply from

source/Generation unit it can lead to total blackout of the system.

Page-28

7. Operational Interruption

It is necessary to interrupt customer service when performing work on the radial distribution

systems. As per Assela substation workers explanation, the feeder line interrupts voluntarily

i.e. when utility technician ask to interrupt the feeder line for maintenances, load transfer and

new transformer erecting and new feeder line installation for new areas.

8. Transmission Line Fault /TLP

Transmission line is used to transport generated power from Awash II with 132KV to Assela

substation. Transmission Line Fault /TLP are the fault that occurred on the transmission line

which cause total power interruption in Assela substation. Therefore any fault, inability to

transmit or any constraints violated in the transmission line which caused inadequate

problems in Assela distribution system.

9. System overloads (SOL)

This interruption type does not frequently occur and it’s general to all substations. It’s in

distribution system level. Faults in some Generation plants cause power shortage to supply

all loads. There has been a record of total blackout of system. Some generation plants faced

technical problem and power access had been short. System overload also occurs due to

imbalance of power demand and power generated during peak customer demand. In some

seasons water levels of hydropower plant decrease and generating capacities are limited.

Moreover system overload occurs. When Generated Power is below the total demand

decrease and generating capacities are limited. Moreover system overload occurs as a result

of poor load forecasting. If the available generation cannot supply the loads or if any

constraints are violated, the system is inadequate. In case of Assela all load are interrupted.

10. Power transformer overload/PTOL

The Service life of transformers is influenced by the temperature rise of winding and

temperature rise of oil due to the KVA loading. Overloading cause excessive temperature

rise and deterioration of the insulation and the oil overload reduce service life of the

transformers. The over loaded transformer beyond its rated name plate can lead to failures.

Page-29

Figure 3.1 percentage of recorded fault in Assela substation Gumguma feeder line

The above chart indicates that the percentage average duration recorded in three year of

Gumguma feeder line. DPEF is the highest percentage observed in the system. This is may

be environmental factors, thus it has a number of trees/forests it crosses. The second highly

observed fault type is DPSC, this is also may cause when a tree is inserted between two

different line or may be animal/ape bring conductor and short the line. So in general the DL

is passing through forest that is why the line is largely affected by these faults.

3.6. Reliability Evaluation and Analysis Methods Reliability of a distribution system using several performance measures which is reliability

indices that includes measurements of outage duration, frequency of outage, system

availability and response time. Reliability analysis needs interruption duration and

frequency, customer interrupted and load connected. Under this chapter the collected failure

data and basic electrical data of the power system which are necessary for reliability analysis

are presented. These data are analyzed to identify the current reliability status of the feeder

line and to distinguish the main problem of interruption.

Reliability evaluation of distribution systems consist of two main approaches. [26], [28],

[32].

25%

20%

6%5%6%

14%

6% 0%0% 18%

Fault recorded in gumguma line

DPEF

DPSC

DTEC

DTSC

TLP

SOL

GUP

DLOL

PTOL

op

Page-30

Simulation methods based on drawings from statistical distributions (Monte Carlo).

Analytical methods based on solution of mathematical models.

The Monte Carlo techniques are normally time consuming due to large number of drawing

necessary in order to obtain accurate results. The fault distribution from each component is

given by a statistical distribution of failure rates and outage times.

The analytical approach is based upon assumptions concerning statistical distribution of

failure rate and repair times. The most common evaluation techniques are using a set of

approximate equation of failure mode analysis. This method is less time consuming than the

simulation method, but suffers from problem representing repair times adequately.

The analytical approach to reliability evaluation of radial distribution system shall be used.

The approach is called Reliability in Radial systems. The vast majority of techniques have

been analytically based and simulation techniques have taken minor role in specialized

applications. The main reason for this is because simulation generally requires large amount

of computing time, and analytical models and techniques have been sufficient to provide

planners and designers with results needed to make objective decisions. Analytical

techniques represent the system by a mathematical model and evaluate the reliability indices

from this model using direct numerical solutions. They generally provide expectations

indices in a relatively short computing time. Reliability indices are usually evaluated by

analytical approach based on failure mode assessment and the use of equations.

3.7. Data Analysis The analytical approach calculates the average reliability indices using a set of mathematical

equations hence the procedure is relatively simple and requires a reasonably small amount of

computer time. The analytical approach is based on assumptions relating to the statistical

distributions of failure rates and repair times [32].

In this thesis, the primary as well as secondary data are collected from Assela substation.

The secondary data as frequency and duration of power interruption of Gumguma line

distribution system for three year (2009-2011 E.C.) are analyzed and interpreted and the

primary data of the total length of 265.2 KM the feeder is taken for load point indices

interpretation. The frequency and duration interruption and the length of the feeder are used

to calculate failure rate and mean time to repair of each failure [29]. The data obtained from

Assela substation are required to calculate the failure rate and mean time to repair. These

Page-31

data obtained are directly or indirectly used to design the existing system of Gumguma line

which is selected feeder in this thesis as a case study.

The performance of Gumguma line being evaluated using commonly used reliability indices.

These indices provide customer risk dimension accordingly this thesis present the result of

the reliability indices obtained by analytically for Gumguma line distribution system only. In

this thesis the reliability analysis of electrical distribution system in the line is carried out.

The system reliability is evaluated for systems feeder determining its performances indices.

The reliability is evaluated for system feeder line load point. While calculating the reliability

indices of the line only sustained interruption are considered. The collected secondary data

from Assela substation as sustained interruption in frequency and duration the whole

analysis is made only as system average indices of sustained interruption, no momentary

indices are considered additionally interruption recording method is not only on basis of how

many customers are affected by fault occurrence but also many delivery points are

monitored to clear the fault.

The reliability indices of Gumguma line of the Distribution system is calculated with the

help of ETAP 16 software package. To predict the reliability indices with ETAP 16

software, the value of failure rates and mean time to repair for each component are

necessary.

Failure rate:- To estimate the failure rate of the line per kilometer, the total number of

outages should be divided by the feeder length (KM) as indicated in the following equation

[38], [44].

yearfeederoflength

yearsbaseoferallofsumrateFailure

*

.int)( (3.1)

008.33*2.265

)918753722(

frequencyerAverage

durationerAverageMTTR

.int

.int (3.2)

286.1667.797

51.1025MTTR

Page-32

From the above equation, the calculated average failure rate of the line and repair times per

km of the existing feeder are 3.008(Interruptions /km. year) and 1.286 (Hrs. /interruption)

respectively. The failure rate of transformer, Breaker and bus bar is 0.005, 1.05 and 1.01

respectively but also their MTTR is 200, 50 and 2. [30], [32].

ETAP 16 software use failure rate and MTTR equation to predict the basic reliability

parameters for reliability analysis are calculated. To estimate the failure rate of a component

ETAP 16 uses combination of active failure rate and passive failure rates together. The

active failure rate in number of failures per year per unit length. The active failure rate is

associated with the component failure mode that causes the operation of the primary

protection zone around the failed component and can therefore cause the removal of the

other healthy components and branches from service, after the actively failed component is

isolated, and the protection breakers are reclosed. This leads to service being restored to

some or all of the load points. It should be noted, however, that the failed component itself

(and those components that are directly connected to this failed component) could be

restored to service only after repair or replacement. While μp is the passive failure rate in

number of failures per year per unit length. The passive failure rate is associated with the

component failure mode that does not cause the operation of protection breakers and

therefore does not have an impact on the remaining healthy components. Repairing or

replacing the failed component will restore service [Software Library]. As there is no means

of isolating a specific faulty area in the system, μp is assumed as zero in the modelTable3.4

below show the value of Gumguma feeder line reliability indices which are calculated with

the help of ETAP 16 software.

Table3.4 Reliability indices for existing system

SUMMARY System Indexes

AENS 6451.4710 MW hr. / customer. Yr.

ASAI 0.8781 pu

ASUI 0.12190 pu

CAIDI 1.474 hrs. / Customer interruption

EENS 322573.500 MW hrs. / Yr.

SAIDI 1067.8870 hrs. / Customer. Yr.

SAIFI 724.2955 f / customer. Yr.

Page-33

3.8 Summary of the Result of Data Analysis for Existing Gumguma Feeder Line The Existing system data analysis work describes system availability metrics and metrics

regarding unreliability. The results of the reliability indices from the data analysis of the

existing system compared with the bench marking of the computed reliability indices of

different countries, it is obvious that the Gumguma feeder Line distribution system has

worse performance and it needs to be improved up on to increases its reliability indices from

table3.4. The reliability indices from calculated values are used to measure the performance

of the distribution system/ Gumguma feeder Line/ for sustained interruption. The results of

reliability indices are explained as followed:-

SAIDI measures the total duration of an interruption for the average customers

during given time period. It is equal to hr. per customers per year. This indices show

that every customers experiences1067.8870 hrs. Per year that is customer was out for

1067.8870 hrs. Per year. This SAIDI result compared to the bench marking. It is

extremely large. Hence this provides that there is great reliability problem in the

existing Gumguma feeder line.

SAIFI is the average number of time that a feeder line customers experiences an

outage during the year from this point of view, the result of SAIFI is equal to f per

724.2955 customers per year. That is, per year customers at Gumguma feeder line

has 724.2955probability of experiencing a power outage. The value of this SAIFI is

compared with the bench marking values. It is much greater than the maximum value

of the bench mark. This clearly indicates that there is serious reliability problem in

the Gumguma feeder Line

CAIDI, once an outage occurs the average time to restore service is found from the

customer. The value of CAIDI of Gumguma feeder line is1.474 hrs. per customer

interruptions, i.e. on average, any customer who experienced an outage on a year was

out of services for 1.474 hrs.

ASAI, it is the average services availability index that services was available during a

given time period to the total customer hours demanded. I.e. it shows the fraction of

times that a customer has received power during the reporting period. The power

supply of the over all of Gumguma feeder Line 0.8781 is pu (87.81%) available as

show in table3.4.

Page-34

EENS: It indicates the un-served or unsold energy of each feeder. For the overall

system, the total unsold energy was 322573.500MWhr. /Yr. as given in Table3.4

AENS: This index represents the average energy not supplied per customer by the

system. The overall system has an AENS value of6451.4710MWhr. / Customer. Yr.

In general, based on the data analysis the following points can be drawn:

The reliability of the Gumguma feeder line does not meet the requirements as

compared to the bench marks of different country and the reliability of this feeder is

not good enough as compared to the international reliability indices of best

experienced countries.

There is high unavailability of services in the network.

3.9. Bench Marking for Distribution System Reliability Indices The standard with reliability of a distribution system in measured against is known as

reliability bench mark. The standards are given in order to provide a justification and given

acceptable margin for the reliability performance of distribution network [30]. The annual

value of SAIFI and SAIDI for each of the participating countries shown in the table3.5. The

countries gives emphasis to the power quality and reliability. From the table3.5 Germany has

high reliable power delivery compared to other developed country. Germany has lower

SAIDI which has lower sustained interruption duration/ shorter in duration of power outage

in a year/ but As considering USA compared to other eight countries. It is considered as

unreliable. The idea of power reliability is tremendously large which covers all parts of the

ability of the system to satisfy the customer’s requirements without the overburdening the

tariff. [31] The commonly used reliability indices for distribution system that must use to

assess the previous performance and predict the next performances of power system.

Table3.5 International comparison of reliability indices [31]

Country SAIDI SAIFI United State/USA/ 240 1.5 Australia 72 0.9 Denmark 24 0.5 France 62 1.0 Germany 23 0.5 Italy 58 2.2 Netherlands 33 0.3 Spain 104 2.2 UK 90 0.8

Page-35

3.10. Reliability cost and worth Distribution system is used to deliver electrical energy to the consumers. In modern society

the life greatly depends on the electrical energy because of its own advantages than other

form of available energies. When power is interrupted both utility and customers faces

different social problems and interruption costs.

The majority of the outages seen by customers are caused by failure in the distribution

system. The reliability of planning approach is based on cost of un-served energy. This is the

economic loss the customers experienced due to un-served energy as a result of planned or

unplanned interruptions. The approach balances the coast of improving service reliability for

customers and the economic benefits of such improvements. The importance of the power

grid depends on the customers being supplied. It is known truth that the reliability of a

system can be increased by increased investment. At the same time the outage costs of the

system will decrease and this lead to the concept of an optimum reliability [29], [31]. The

essential problem in applying the concept of optimum reliability is lack of knowledge of the

true outage cost and the feature that should be included. The outage cost has seen by utility

and the customers. The utility outage costs include: loss of revenue from customers not

served; loss of customer goodwill; increased expenditure due to maintenance and repair.

Power Interruption Cost Evaluation in the Distribution system

Electricity supplies in Ethiopia are at reasonable cost. If it supply’s with quality levels, it

becomes basic condition for development economic growth and welfare. Customer

Interruption cost is simply revenue lost by the utility companies due to power interruption to

the connected customers. This revenue may be in the form of system failure, ruin process,

over time pay and loss of production. When customer faces interruption, there is an amount

referred to as the customer cost of reliability. Such costs are of tangible and intangible types

and also there is an opportunity cost. But assessing the interruption cost from the customer

side is difficult. Power interruption costs are in both utility side and the customer side.

Page-36

Power Interruption Cost from Utility Side

Power interruption cost from utility side is estimated on customer data, interruption data and

cost outage data. Assela substation record interruption data that are usually recorded in the

form of interruption duration, interruption frequency and load reading of each feeder on each

hours. The utility has data of customers.

The energy is a very important terms to estimate the interruption cost of system for a typical

years. The basic factor used for cost estimation is the tariff (price in birr) for different type of

customers

Expected interruption cost/ EIC/ is calculated for each delivery point in the area by

computation of the contribution to EENS and EIC for each and every interruption expected

to occur during a year. The expected frequency and duration of each failure giving

interruption to the delivery point, in combination with the expected load and the specific

interruption cost for each interruption duration are used to obtain the delivery point EIC.

KWHperTariffEENSEIC * (3.3)

The average Equivalent Flat Rat of the utility is 1.03764cents

The Electrical Energy not supplied is

EENS =340200.300 MW hrs. / Yr.

birrcentiyMWhrEIC 665.334715103364.1*/500.322573

Generally the utilities loss 3347151.6654E.birr per year because of power unavailability or

power outage in the Gumguma feeder line.

Ethiopian Electricity Tariff from Assela utility in Appendix -D

Page-37

Figure 3.2 single line diagram of existing system

Cut-view of single line diagram

Page-38

CHAPTER FOUR

Proposed Solution for (GSM based) improving reliability

of distribution line

The system designed for detecting and locating power line faults caused by various

destructing forces which may be natural or man-made. The set of current and voltage sensors

attached with the line and control units help in monitoring the line continuously. The relay

disconnects the faulty section of line from mains so as to minimize accidents. This is

achieved with the help of a micro-controller that will produce control signals to cut the relay

whenever a fault is found out. All the units are named by using an identification number

SIM inserted in GSM so that under which unit the fault is found can be easily identified and

the fault location is calculated by impedance based algorithm feed in to microcontroller. The

mode of operation can be seen in Fig. 4.1 below.

It mainly divided in to two sections: The line unit and the control unit. The two sections are

connected wirelessly. Both are powered by DC power supply. The power supply can be a

DC battery or a solar panel. The line unit consists of mainly a microcontroller, voltage and

current sensors, GSM and relay. The whole system contains Seven (7) line units which are

placed in different points in the distribution line. The main function of line unit is to find the

faults in the distribution line and inform the corresponding location to the control station.

The control station consists of a Microcontroller, GSM modem, LCD, buzzer etc. Initially,

when the system is powered, the controller reads the sensor values that is, the line current,

voltage, and power values. The controller first check for the magnitude of voltage and

current. If the magnitude of voltage in all the three lines is between 200 to 220v the

controller understand that there is no fault and the control station displays all the three line

normal. But if the voltage is below the normal voltage, and the controller understands that

there is abnormal condition in the system and determines what type of fault and also

determine the distance of fault occurred based on the program feeded. If the above

mentioned fault is present, the micro-controller gives information to cut the relay and in the

control station the information is displayed on the LCD the status of all phase line and

distance of fault occurred. And the GSM also transmit the status of line in text mode to the

operator. The relay interrupt power supply if there is any fault in the system and again check

the line if the fault is temporary, so that if the fault is temporary the relay reclose the load

and the power is continued to deliver the system but if the fault is temporary the relay de-

Page-39

energized the load and separate from the system until the fault is removed and manually

switched on.

4.1 System Hardware The automatic fault detection and location system comprises of a current transformer, a

voltage transformer, a microcontroller, an RS-232 connector GSM modem and an LCD as

shown in the block diagram in fig 4.1

AC Load

Relay coil

Microcontroller

CT VTRelay

control

GSM

Microcontroller

GSM

LCD

Master/control station

Line station

Figure 4.1 block diagram of fault indicator

4.1.1 Working principle of the blocks Power Supply The power supply uses a step down transformer to step down the input mains voltage to a

voltage level suitable for the electronics within the device. A center tapped transformer, with

two diodes for full wave rectification is used to convert the ac voltage to a pulsating dc

voltage followed by a filter, comprising of a capacitor to filter out (smooth) the pulsation

Microcontroller The microcontroller performs the major functions of decision and control. The input voltage

monitor is connected to the microcontroller which provides a sample of the input supply

voltage to the microcontroller for comparison with the programmed set values in the

microcontroller. The microcontroller was used in the design in order to reduce the

complexity of the design and to ensure an easy interface with a liquid crystal display.

Page-40

Rectifier Rectifier: Often called as super diode, the rectifier is used in order to convert the alternating

value of line current into dc value. Also a three phase rectifier can be used, but due to high

output current and harmonic content former is preferred. The rectifier is made up of

Op‐Amp in conjugation with capacitor and resistors.

GSM MODEM

A GSM modem is a wireless modem that works with GSM wireless networks. A wireless

modem is similar to a dial-up modem. The main difference is that a wireless modem

transmits data through a wireless network whereas a dial-up modem transmits data through a

copper telephone line. Most mobile phones can be used as a wireless modem. To send SMS

messages, first place a valid SIM card into a GSM modem, which is then connected to

microcontroller by RS 232 cable. After connecting a GSM modem to a microcontroller, we

can control the GSM modem by sending instructions to it.

4.2 Mode of operation.

The set up or field device consists of 3 major components, instrument transformer (CT and

VT), GSM modem and microcontroller. The primaries of the CT and VT which are

connected to the line sense the corresponding current and voltage values of the system and

feed the output to the ADC of the microcontroller which converts the signal to a digital form

using LM358 IC in order to be processed by the CPU of the microcontroller. The

microcontroller serves as the central point of the set up. It contains a set of programming

codes which have been stored in the EEPROM which enables it to classify the fault type

based on the voltage and current values. Based on the program, the microcontroller

compares these values to see whether they are within the range required. If the voltage and

current values are out of range as compared to the reference, it gives an indication of a fault.

The microcontroller also calculates the fault distance, relative to the device based on an

impedance-based algorithm and then relays this information to the modem for transmission.

In summary, the microcontroller classifies, calculates the fault distance and relays the

information to the modem for transmission via the serial communication interface (SCI)

which serves as an interface between the microcontroller and the modem. The RS-232 serves

as the connector between the microcontroller’s serial communication port and the GSM

modem. The device is placed in the boundary of the sectionalized regions in the distribution

system and the location of the fault is calculated relative to the position of the device. The

unique identity of the SIM card in the GSM

Page-41

Algorithm of fault location and detection using GSM

Step1. Switch on the power supply

Step2. Initialize the LCD and GSM

Step3. Initialize the pin modes and variable

Step4. Voltage analog read by the ADC

Step5. Compare the value of voltage with normal

Step6. Display the status of each line and the GSM starts to transmit the magnitude of

Voltage, current, and power.

Step7. Else if voltage is less than normal magnitude, display fault type and location.

Step8. End

Page-42

A

End

start

Pull value from ADC

no

Is the value within range?

Analize and classify fault

Calculate distance of fault from device

Transmit fault data and distance

yes

Figure 4.2 Flowchart of proposed approach

Page-43

4.3 Modeling Distribution Network fault location and Reliability improvement Faults cause to decrease power quality, destroyed reliability indices, decrease benefits, and

satisfaction of consumers from distribution companies. Therefore, this is favorable for

consumers, if location of fault is found quickly and repaired them; consequently time of

restoration is reduced. When a permanent fault occurs in the network, faulted section of the

network is detected with FI, and system automatically is isolated faulted section with

autoreclosure and switches, and the sane section of the network is resupplying immediately.

Faulted section has to be repaired and then resupplied. The FI can decrease the process of

fault detection, and it improved the reliability cost.

4.4 Modeling and assessment technique The FI can decrease the process of fault detection, and it improved the reliability cost. For

example a sample feeder with a FI [41].

S FI

A=8KM B=4KM

Fig 4.3: A Typical distribution system with one FI

Assume that the total fault detection time of this feeder is 1 hour, and it is depended to

feeder length. With installation of a FI, the fault locating time for upstream part of the feeder

is as below.

Assume upstream length is A and the downstream is B the time taken in the upstream is:

LBLA

LTt A

A

* (4.1)

Where tA is time taken for upstream, LA is distance of upstream; LB is distance of low

stream and T is total time taken to detect the distribution line fault.

6667.048

8*1

At

Page-44

And the fault locating time for downstream part of the feeder is.

BA

BB LL

LTt

* (4.2)

Where tB is time taken to detect downstream

3333.084

4*1

Bt

In general, with installation of n FI on distribution feeder, that feeder is divided to n+1 part,

and the fault locating time for i th part is calculated as follow:

(𝑇 )𝑖 = 𝑇 × [∑

] (4.3)

Where Li: Length of part i th

T0: average of fault locating time without FI

With calculation the fault locating time and also with regarding repair or switching time, and

with application of customer damage function, can be calculating the customer interruption

cost.

Page-45

4.5 Comparisons of distribution line with and without FI

Report outageFault occur Crew on location Fault detacted Isolating faulty system from rest Feed back to normal

15-30minute 10-15minute5-15minute 15-30minute

Travel tme Fault investigation Repair time

45-90 minute

Figure 4.4: Activity-time diagram for a feeder fault without FI [42].

Report outage

Fault occur Crew on location Fault detacted

Isolating faulty system from rest Feed back to normal

Travel tme Fault investigation Repair time

Isolating faulty section and report location of fault

1-5minuteFigure 4.5: Activity-time diagram for a feeder fault with FI

AS we compare the successful implementation of FI system results mainly in Operational &

Maintenance benefits, financial benefits, and customer related benefits [41]. These benefits

are related to the improved reliability, reduced the time of crew to search occurred faults and

increase their productivity in operation and also reduced maintenance expenses, reduced

fault location time, increased revenue due to quick restoration, enhanced system efficiencies

and reduce consumer direct and indirect cost satisfaction.

Page-46

CHAPTER FIVE

Results and Discussions

5.1 Introduction GSM based fault location can be implemented by using electronic control recloser or

combination of recloser and switches /manual or automatics/ which have the purpose of

automatically switch and protect the feeder line with the aim of reducing restoration time,

and trying to eliminate faults or outages from the system. The Automatic recloser is selected

for automatically detect fault and isolate the fault line. Pole mounted automatic recloser

allows the feeders to detect the fault and isolate the fault section and based on the

instantaneous fault voltage and current measurement signals is processed by the arduino

microcontroller to determine the length/distance and type of fault sent to the control center,

at the control center show the outage zone/area of the faulted feeders. The recloser is

incorporated with microcontroller and wireless communication devices equipment in order

to identify fault location in the distribution system automatically at the node of divided zone

and finally the GSM will send this information to the operator/Authorities. Gumguma feeder

line is protected by circuit breaker of CT 75-150/1/1A rated at the outgoing of the

transformer at the substation and deactivated auto recloser for the safety of devices. This

feeder line has no section or division of zone and has no any protective devices other than

substation circuit breaker and line section switch. When the fault occurs at one point far

from substation or in one lateral feeder line, the total feeder lines are become out. All

customer on this feeder experienced power interruption. Power interruption stay for long

duration of time until the lateral faulted line are located and isolated manually. Hence fault

location and isolation is based on try and error or tracing of the line which take several hour

to restore power to the feeder. This thesis divides the feeder line into different 7zones. The

zone concept refers to a systematic method of dividing DN in to manageable area/zone/

based on length, loads, load criticality and disturbance vulnerability [25]. This thesis

proposes automatic recloser with integration of microcontroller and wireless communication

system and GSM system which make DS automatic to enhance reliability improvement. All

division zones are equipped with automatic electron control recloser, microcontroller, and

wireless communication technology. Placements of number of automatic recloser on

different point of feeder line are chosen by considering the different criteria based on the

utility faces the challenge of fault identifying, isolation and restoration manually.

Page-47

Determining number of switch/ auto recloser

The system has reasonably high reliability as interruption durations and energy losses are

minimized due to the installed sectionalizing switches.

Reliability indices such as the system average interruption frequency index (SAIFI), system

average interruption duration index (SAIDI), system unsupplied energy due to power

outages (ENS) can be calculated for this system. The reliability indices, SAIDI, ENS can be

calculated [40].

)cos**)( tswitchNstariffENSwsENSswsMaxproft (5.1)

Where, ENSwsw = ENS without any switch in radial distribution system.

ENSsw =ENS considering switches in the system.

Ns=Number of switches placed in the system n is total number of bus.

Table 5.1 relation of no of switch ENS, SAIDI and maximum profit

no of switch

ENS Switch cost

SAIDI Profit

0 322573.5 0 1067.887 0 1 288131.6 150000 639.7178 207300.3 2 158434.6 300000 529.2432 1402777.0 3 145866.6 450000 501.405 1383157.0 4 125898 600000 481.1792 1440312 5 125895 750000 447.308 1290343.0 6 122236 900000 416.56 1178301.0 7 122233 1050000 404.62 1028332 8 122225 1150000 392 878073 9 122218 1300000 379.5 728487.95

Page-48

relation b/n profit and cost of switch

0

200000

400000

600000

800000

1000000

1200000

1400000

1600000

1 2 3 4 5 6 7 8 9

no of switch

switc

h co

st a

nd m

ax. p

roft

in

Birr

Figure 5.1 relation b/n switch cost and maximum profit

As we increase the number of switch SAIDI will continuously improve but the profit gained

is declining due to cost of switch and due to deference in ENS is minimum as we increase

switch. So that we get maximum profit when the number of switch is 7. And its location is

determined by length of feeder line, no of load (load density) and by the criticality of the

load.

(Cost of switch is 3000- 8000$) [43].

So average Cost of a switch = 150000Et.Birr

5.2 Case-1 Placement of the three recloser in Feeder Line Recloser is designed to operate like station breaker. The recloser incorporated protective

relaying equipment which can be set to trip specific over current conditions and reclosed at

specific time interval [25]. It used on the main feeder of the circuit and are generally used on

lateral branches. The Gumguma feeder line could be divided in to Three zone/area for easily

manage the zone during the utility fault management case apply three automatic reclose to

protect each zone to the down side. The simulation focuses on evaluating the impacts of

using all recloser at the same time on reliability of the system.

Page-49

From Table5.2 illustrates the reliability improvement because of inserting recloser for each

division of zones of protection which are formed based on topology and environmental

factor, length of feeder, economical benefit and sensitivity for town as explained in the

introduction of this chapter. From this table, the reliability indices are improved. As the

reliability indices shown in the table5.2, SAIDI is reduced from 1067.887 to 512.hr per

customer per year i.e. SAIDI is improved by 52.047% from the existing status and also

SAIFI is reduced from 724.2955 to 338.5966 f per customers per year. I.e. SAIFI is

improved by 53.25% from the existing status; EENS is reduced from 322573.5 to 145866.6

Mw hr. per year. The Utility EIC /loss of earning Ethiopian birr due to EENS is also reduced

from 334715166.54.birr to 151322010.84.birr i.e. the utility get profit about

183393155.7cents=1833931.557et.birr per year in addition to ordinary profit from sold

electric consumption if this methodologies applied

Figure 5.2 Single line diagram of case one

Page-50

Table 5 .2 Result of Reliability indices for Case 1

SUMMARY System Indexes AENS 3169.1640 MW hr. / customer. Yr. ASAI 0.9428 pu ASUI 0.05724 pu CAIDI 1.481 hr. / customer interruption EENS 145866.6 MW hr. / Yr. SAIDI 512 hr. / customer. Yr. SAIFI 338.5966 f / customer. Yr.

5.3 Case-2 Placement of the six recloser in Feeder Line It used on the main feeder of the circuit and are generally used on lateral branches. The

Gumguma feeder line could be divided in to Six zone/area for easily manage the zone during

the utility fault management case apply Six automatic reclose to protect each zone to the

down side. The simulation focuses on evaluating the impacts of using all recloser at the same

time on reliability of the system. From Table5.2 illustrates the reliability improvement

because of inserting recloser for each division of zones of protection which are formed based

on topology and environmental factor, length of feeder, economical benefit and sensitivity

for town as explained in the introduction of this chapter. From this table, the reliability

indices are improved. As the reliability indices shown in the table5.2, SAIDI is reduced from

1067.887 to 417.2679hr per customer per year i.e. SAIDI is improved by 60.93% from the

existing status and also SAIFI is reduced from 724.2955 to 276.0437f per customers per

year. I.e. SAIFI is improved by 61.1888% from the existing status; EENS is reduced from

322572.5 to 122236 Mw hr. per year. The Utility EIC /loss of earning Ethiopian birr due to

EENS is also reduced from334715166.54cents to 126807626cents=1268076.26et.birr i.e.

the utility get profit about 2079075.4054.birr per year in addition to ordinary profit from sold

electric consumption if this methodologies applied

Page-51

Figure5.3 Single line diagram of case Two

Table 5 .3 Result of Reliability indices for Case 2

SUMMARY System Indexes

AENS 2464.2160 MW hrs. / Customer. Yr.

ASAI 0.9524 pu

ASUI 0.04763 pu

CAIDI 1.512 hrs. / Customer interruption

EENS 122236 MW hrs. / Yr.

SAIDI 417.2679 hrs. / Customer. Yr.

SAIFI 276.0437 f / customer. Yr.

5.4 Case-3 Placement of the seven recloses in Feeder Line It used on the main feeder of the circuit and are generally used on lateral branches. The

Gumguma feeder line could be divided in to seven zone/area for easily manage the zone

during the utility fault management case apply seven automatic reclose to protect each zone

to the down side. The simulation focuses on evaluating the impacts of using all recloser at

the same time on reliability of the system. From Table5.4 illustrates the reliability

improvement because of inserting recloser for each division of zones of protection which are

formed based on topology and environmental factor, length of feeder, economical benefit

and sensitivity for town as explained in the introduction of this chapter. From this table, the

reliability indices are improved. As the reliability indices shown in the table5.3, SAIDI is

reduced from 1067.887 to 404.9044hr per customer per year i.e. SAIDI is improved by

Page-52

62.084% from the existing status and also SAIFI is reduced from 724.2955 to 259.2716 f per

customers per year. I.e. SAIFI is improved by 64.2036% from the existing status; EENS is

reduced from 322573.5 to 122233Mw hrs. Per year. The Utility EIC /loss of earning

Ethiopian birr due to EENS is also reduced from334715166.54 .birr to

126911366.4cents=1269113.66 birr i.e. the utility get profit

about207803800.14.cents=2078038.00birr per year in addition to ordinary profit from sold

electric consumption if this methodologies applied

Fig 5.4 Single line diagram of case Three

Page-53

Table 5 .4 Result of Reliability indices for Case 3

SUMMARY System Indexes AENS 2464.2040 MW hrs. / Customer. Yr. ASAI 0.9538 pu ASUI 0.04622 pu CAIDI 1.562 hrs. / customer interruption EENS 122233 MW hrs. / Yr. SAIDI 404.9044 hrs. / Customer. Yr. SAIFI 259.2716 f / customer. Yr.

Figure 5.5 Relations of fault indicator and SAIDI

As we observe from the above figure if we increase the no of switch/fault indicator (FI) SAIDI continuously improved. So that FI improve the time of fault detection and improve the reliability of a distribution line.

5.5 Simulation and result The working of distribution line fault detection and location using GSM is based on the

Microcontroller. In this the distribution line consists of 220v, 50 Hz supply using VT, as that

we can’t use the 220 v supply directly for microcontroller. So instead of that we are using

the step down transformer for step down the input voltage into lower ac supply which makes

as the supply voltage. The step down voltage from the transformer is given to rectifier which

converts the ac supply into dc supply for the purpose of only the dc source or supply is used

as the source for the microcontroller. After converting as dc supply, the boost circuit or op-

Amp which take variable input from 3v to 32v which act as a sensor by supplying variable

output for the microcontroller. And the microcontroller makes decision based on program

feeded on it.

0

200

400

600

800

1000

1200

0 1 2 3 4 5 6 7 8

SAIDI

No of FI

SAIDI Vs F I

Page-54

The circuit is simulated for normal as well as faulty operation. The normal value is set to

200v to 220v in the program. Using the variable supply, the analog input to the ADC port of

the microcontroller was increased or decreased based on the supply of input transformer.

When the supply is normal the LCD in the control station display all the three lines normal

and the virtual terminal also display the magnitude of voltage, current and power.

Figure5.6 Schematic Diagram of the Proposed System/control station

Page-55

Figure 5.7 Schematic Diagram of the Proposed System/line or field station

Figure 5.8 Schematic Diagram whiles the circuit continuously checking lines under normal

condition.

Page-56

Table 5.5 Result of each line under normal condition.

S/NO Voltage across lines LCD display at cont. station

Virtual display KM of fault location both on LCD & Virtual display

Line voltage Voltage(V) Current(A) Power(W)

1 Line-1 215 Normal 215 0.18 38.7 2 Line-2 215 Normal 215 0.18 38.7 3 Line-3 215 Normal 215 0.18 38.7

Simulation that shows the normal operation of a line that, when the input voltage and current

is in normal range the microcontroller understands based on the given instruction make a

decision to order the GSM to transmit the line information to operators and control station.

Thus the control station display all the three line is normal and in the operator the

information is displayed the magnitude of voltage-1, current-1, voltage-2, current-2voltage-

3, current-3, power-1, power-2 and power-3 of their respective line. The load on the line unit

operates normally and the buzzer in the control station is in deactivated mode.

Figure 5.9 Schematic Diagram when ground fault occur on phase-1/line-1

Page-57

Table 5.6 Result of simulation when ground fault occur across Line-1 at 9KM

S/NO Voltage across lines LCD display at cont. station

Virtual display KM of fault location both on LCD & Virtual display

Line Voltage Voltage(V) Current(A) Power(W)

1 Line-1 5 Ground fault 15 0.05 0.76 9 2 Line-2 215 Normal 215 0.18 38.7 3 Line-3 215 Normal 215 0.18 38.7 Simulation shows that when fault occus across line-1/line to gound fault/ voltage across this

line is decreased below minimum value, so based on the code the micocontroller understands

that fault is occured on this line when voltage magnitude is below normal , there fore the

controller order the the GSM to tansmit the status of line to control station. Based on this

fault location can be calculated with the formula given to it. Thus , the status of line is

displayed on the control station and fault location also diplayed in km from the line unit.

In the the vitual terminal the value of current , voltage and power is displayed . The faulted

line/ line-1 location is also displayed in km. The load will deactivated from the supply and

the buzzer starts to give sound in the controll station.

Page-58

Figure 5.10 Schematic Diagram when Line-1and Line-2 short circuited

Simulation shows that when short circuit fault occus between line-1 and line-2 voltage

across this line is equal in magnitude but decreased below minimum value, so based on the

code the micocontroller understands that fault is occured both on line-1 and line-2., there

fore the controller order the the GSM to tansmit the status of line to control station. Based on

this fault location can be calculated with the formula given to it. Thus , the status of line is

displayed on the control station that display line-1 short , line-2 short , line-3 normaland km

magnitude also displayed (location of fault occurred) and the fault location is diplayed in

km from the line unit.

In the the vitual terminal the value of current , voltage and power is displayed . The faulted

line/ line-1 and line-2/ location is also displayed in km. The load will deactivated from the

supply and the buzzer starts to give sound in the controll station.

Page-59

Figure 5.11 Schematic Diagram when ground fault occur on line-3

Simulation shows that when fault occus across line-3/line to gound fault/ voltage across this

line is decreased below minimum value, so based on the code the micocontroller understands

that fault is occured on this line when voltage magnitude is below normal , there fore the

controller order the the GSM to tansmit the status of line to control station. Based on this

fault location can be calculated with the formula given to it. Thus , the status of line is

displayed on the control station and fault location also diplaye in km from the line unit.

In the the vitual terminal the value of current , voltage and power is displayed . The faulted

line/ line-1 location is also displayed in km. The load will deactivated from the supply and

the buzzer starts to give sound in the controll station.

Page-60

Figure 5.12 the operation of auto recloser/relay / during fault occur

When fault occurs across a line the auto recloser start to isolate/de-energize the line after

some delay of time then the switch /recloser stay ON for some seconds whether the fault is

permanent or temporary and reclosed after predetermined delay of time, then the recloser

again open/de-energize the load (the recloser in ON position) if the fault is permanently exist

but if the fault is removed/temporary the recloser stay de-energized.

Page-61

Figure 5.13 the operation of auto recloser under normal condition

When the system/ line is at normal condition the recloser is in off position and the load flow

continuously , the control panel on LCD display the status of the line and the virtual

terminal show the magnitude of voltage , current and power.

Page-62

Table 5.7 Summary of result displayed in each case

when all the supply voltage and current is in normal range

on the virtual terminal on the LCD at the control station

V-1 V-2 V-3 I-1 I-2 I-3 pow

e-1

pow

e-2

pow

e-2

Km L-1

L-2

L-3

Km

213.

85

213.

85

213.

85

0.18

0.18

0.18

38.

49

38.

49

38.

49

norm

al

norm

al

norm

al

when voltage across line-1 is less than normal voltage and the other two is in normal range

belo

w n

orm

al 21

3.85

213.

85

belo

w 0

.18

0.18

0.18

Bel

ow n

orm

al

38.

49

38.

49

Km

=(0

.03*

V-1

/I-1

)

gro

und

faul

t

norm

al

norm

al

Km

=(0

.03*

V-1

/I-1

)

when voltage across line-1 and line-2 is less than normal voltage and line-3 is in normal range

belo

w n

orm

al

belo

w n

orm

al 21

3.85

I-1<

0.18

I-2<

0.18

0.18

Bel

ow n

orm

al

B

elow

nor

mal

38.

49

Km

=(0

.03*

V-1

/I-1

)

Shor

t

Shor

t

norm

al

Km

=(0

.03*

V-1

/I-1

)

when voltage across line-1 is less than normal voltage and the other two is in normal range

213.

85

213.

85

belo

w n

orm

al

0.18

0.18

Bel

ow n

orm

al

38.

49

38.4

9

Bel

ow n

orm

al

Km

-1=

(0.0

3*V

-3/I

-3)

norm

al

norm

al

gro

und

faul

t

Km

=(0

.03*

V-3

/I-3

)

Page-63

CHAPTER SIX

Conclusion and Recommendation

6.1. Conclusion This thesis Investigate fault location using GSM for the reliability improvement of Assela

feeder Gumguma line, hence primary as well as secondary data have been organized for

evaluation of the Line reliability using analytical simulation approach with ETAP 16

software using Load point and determined the performance of the existing system based on

reliability indices. In this thesis, collected the cause of the fault from the utility workers

through interview based on substation fault record and through site visited. The feeder is

experienced to the number of power outage due to faults, over load, tree contact, winding

environment, wild animal like ape, and Gureza/colobuses/ farm animal, aging of pole and

equipment, maintenance and operational practices, protection failures and other hence the

response of interview from participant did not show the main and the higher cause of the

fault. Actually they did not level the degree of cause for each fault but they are responding in

one idea is that the power outage duration high because of the challenge of fault finding and

locating the fault through visual tracing, try and error testing due to high level of topology,

the length of feeder, environmental factors. etc.

The existing Assela feeder Gumguma line data analysis gives SAIDI, SAIFI, EENS, etc

which are equal to 1067.8hr/cust/yrs, 724.2f/cust./yrs, and 322573.5Mwh/yrs respectively.

This results has been compared to the bench marking, it is extremely large hence this

provides that there is great reliability problem in the Line. In general the result shows that

the Assela feeder Gumguma line is unreliable. This thesis propose GSM based FL

technology in order to enhance distribution reliability improvement based on the optimum

number and location of pole mounted electronic

Control recloser that automatically detects the fault and isolates the fault, and also it informs

the location of problem happen on the line and this will significantly reduce the time of fault

detection through manual. These enhance the distribution system reliability improvement

and satisfy the customer by reducing impact, duration and frequency of the power

interruption.

This thesis has been dividing the existing DN in to manageable area/zone and applies

technology for protection of each zone using automatic recloser integrating with FL and

GSM communication to the zone of the feeder node and use manual switch for different

lateral feeder and rural feeder line in the zone for isolation of fault feeder. These enhance the

Page-64

distribution reliability improved and satisfy the customer by reducing outage impact,

duration and frequency of power interruption.

This thesis considered three case studies, from these case study, using number of Recloser

and fault indicator circuit , and switching load isolation method in the case fault occurred in

the division zone improve the reliability of the feeder line. From this point of view, SAIDI,

SAIFI, is reduced to 404.9044 f/cust/yrs, 259.2716hrs/cut/yrs. i.e. they improved 62.08%

and 64.19% respectively and also EENS is reduced to124210.2Mwhrs/yrs. i.e. it also

improved by 61.49%. In other word, the utility will get198363.3MWhrs/yrs. are available

for soled because of this method of improvement in addition to the ordinary sold. This

increases the income of the utility and customer and also satisfaction of customer

6.2 Recommendation

It is recommended that:

The primary purpose of the system is to satisfy customer requirements and since the

proper functioning and longevity of the system should found to be essential requisites

for continued satisfaction.

The interruption data recording have to be made systematic and rationalized meaning

that all individual component failure data, localized fault data, have to be precisely

recorded if future system analysis should represent true state of the system. As of

now, the data have been recorded only when there is fault on the feeder. And all the

hard copy data are not kept properly.

Practical implementation of the recommended alternative solution is also important

to improve the reliability of the power distribution system.

If any interested researcher should include GPS for the accuracy of fault location the

reliability of a line improved more.

If the Ethiopian Electric utility applies this project practically, the income collected

from waste power due to service outage increased.

Page-65

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Page-68

APPENDIX APPENDIX A : summary of duration and frequency

Table-a Assela substation gumguma feeder line interruption frequency and duration in

2009E.C.

Month Outage in number September Freq. 63

Dur(Hr.) 70.935 October Freq. 46

Dur(Hr.) 58.47 November Freq. 37

Dur(Hr.) 42.783 December Freq. 72

Dur(Hr.) 86.817 January Freq. 34

Dur(Hr.) 39.015 February Freq. 46

Dur(Hr.) 51.345 March Freq. 66

Dur(Hr.) 89.004 April Freq. 102

Dur(Hr.) 122.711 May Freq. 80

Dur(Hr.) 86.134 June Freq. 47

Dur(Hr.) 58.614 July Freq. 62

Dur(Hr.) 64.69 August Freq. 66

Dur(Hr.) 69.012 Total Freq. 722

Dur(Hr.) 839.53

Page-69

Table- b Assela substation gumguma feeder line interruption frequency and duration

in 2010E.C

Month

Outage in number

September Freq. 56

Dur(Hr.) 90.935

October Freq. 36

Dur(Hr.) 78.47

November Freq. 36

Dur(Hr.) 55.783

December Freq. 47

Dur(Hr.) 58.817

January Freq. 39

Dur(Hr.) 62.32

February Freq. 57

Dur(Hr.) 82.137

March Freq. 69

Dur(Hr.) 89.004

April Freq. 89

Dur(Hr.) 122.711

May Freq. 91

Dur(Hr.) 121.567

June Freq. 83

Dur(Hr.) 97.532

July Freq. 77

Dur(Hr.) 88.89

August Freq. 69

Dur(Hr.) 99.012

Total Freq. 753

Dur(Hr.) 965.041

Page-70

Table-c Assela substation gumguma feeder line interruption frequency and duration in

2011E.C.

Month Outage in number

September Freq. 82

Dur(Hr.) 151.35

October Freq. 86

Dur(Hr.) 117.47

November Freq. 61

Dur(Hr.) 82.783

December Freq. 69

Dur(Hr.) 88.817

January Freq. 54

Dur(Hr.) 53.015

February Freq. 71

Dur(Hr.) 91.137

March Freq. 94

Dur(Hr.) 119.004

April Freq. 104

Dur(Hr.) 122.711

May Freq. 97

Dur(Hr.) 131.567

June Freq. 79

Dur(Hr.) 148.532

July Freq. 59

Dur(Hr.) 84.89

Augest Freq. 62

Dur(Hr.) 89.012

Total Freq. 918

Dur(Hr.) 1197.505

Page-71

APPEDIX- B Average duration and frequency of each year

Table –a Frequency of interruption of type of faults

No

Fault type

Gumguma line

2009E.C. 2010E.C. 2011E.C.

Freq. Freq. Freq.

1 DPEF 95 104 114

2 DPSC 88 76 135

3 DTEF 82 114 112

4 DTSC 126 127 137

5 TLP 18 30 44

6 SOL 79 81 69

7 GUP 63 79 94

8 DLOL - - -

9 PTOL - - -

10 OP 171 142 213

Total 722 753 918

Page-72

Table- b Duration of interruption of type of faults

No

Fault type

Gumguma line

2009E.C. 2010E.C. 2011E.C.

Dur(Hr.) Dur(Hr.) Dur(Hr.)

1 DPEF 286 195.695 288.573

2 DPSC 168.084 166.15 278.294

3 DTEF 59.704 57.051 61.951

4 DTSC 29.389 59.828 58.619

5 TLP 44.793 53.716 78.14

6 SOL 155.586 150.895 133.103

7 GUP 87.578 59.789 53.108

8 DLOL - - -

9 PTOL - - -

10 OP 83.396 221.371 245.717

839.53 965.041 1197.505

Page-73

APPEDIX- C Arduino code for implementation of fault location

#include <SoftwareSerial.h>

#include<LiquidCrystal.h>

int relay=8;

int Read_Voltage_1 = A1;

int Read_Current_1 = A0;

int Read_Voltage_2 = A3;

int Read_Current_2 = A2;

int Read_Voltage_3 = A5;

int Read_Current_3 = A4;

constintrs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 2;

LiquidCrystallcd(rs, en, d4, d5, d6, d7);

SoftwareSerialgsm(0,1);

Float Voltage_1 = 0.0;

Float Current_1 = 0.0;

Float Power_1 = 0.0;

Float Voltage_2 = 0.0;

Float Current_2 = 0.0;

Float Power_2 = 0.0;

Float Voltage_3 = 0.0;

Float Current_3 = 0.0;

Float Power_3 = 0.0;

Void setup ()

{

lcd.begin(16, 4);

Serial.begin(9600);

gsm.begin(9600);

pinMode(relay, OUTPUT);

lcd.print(" three ");

lcd.setCursor(0, 1);

lcd.print(" Phase fault ");

Page-74

lcd.setCursor(0, 2);

lcd.print(" Detector ");

delay(500);

lcd.clear();

}

void loop()

{

int km_1;

int km_2;

int km_3;

Voltage_1 = analogRead(Read_Voltage_1);

Current_1 = analogRead(Read_Current_1);

Voltage_2 = analogRead(Read_Voltage_2);

Current_2 = analogRead(Read_Current_2);

Voltage_3 = analogRead(Read_Voltage_3);

Current_3 = analogRead(Read_Current_3);

Voltage_1 = Voltage_1*(5.0/1023.0) * 270.089;

Current_1= Current_1* (5.0/1023.0) * 1.628;

Voltage_2 = Voltage_2* (5.0/1023.0) * 270.089;

Current_2= Current_2* (5.0/1023.0) * 1.628;

Voltage_3 = Voltage_3*(5.0/1023.0) * 270.089;

Current_3= Current_3*(5.0/1023.0) * 1.628;

Serial.println(Voltage_1);

Serial.println(Current_1);

Serial.println(Voltage_2);

Serial.println(Current_2);

Serial.println(Voltage_3);

Serial.println(Current_3);

Power_1 = Voltage_1 * Current_1;

Power_2 = Voltage_2 * Current_2;

Power_3 = Voltage_3 * Current_3;

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Serial.println(Power_1);

Serial.println(Power_2);

Serial.println(Power_3);

if((200<=Voltage_1 && Voltage_1<=220)&& (200<=Voltage_2 && Voltage_2<=220) && (200<=Voltage_3 && Voltage_3<=220))

{

lcd.setCursor(0, 0);

lcd.print("Line 1 "); lcd.print("Normal");

lcd.setCursor(0, 1);

lcd.print("Line 2 ");lcd.print("Normal");

lcd.setCursor(0, 2);

lcd.print("Line 3 "); lcd.print("Normal");

gsm.println("AT+CMGF=1"); //To send SMS in Text Mode

delay(50);

gsm.println("AT+CMGS=\"+251913846366\"\r");// Phone number to be notified

gsm.println("Normal");// message to be sent

delay(5000);

}

if((200<=Voltage_1 && Voltage_1<=220)&& (200<=Voltage_2 && Voltage_2<=220) && ( Voltage_3<200))

{

lcd.setCursor(0, 0);

lcd.print("Line 1 "); lcd.print("Normal");

lcd.print(" ");

lcd.setCursor(0, 1);

lcd.print("Line 2 ");lcd.print("Normal");

lcd.setCursor(0, 2);

lcd.print("Line 3 "); lcd.print("ground fault");

km_3=(0.03*(Voltage_3/Current_3));

lcd.setCursor(0, 3);

lcd.print("km_3");

lcd.setCursor(5, 3);

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Serial.println(km_3);

lcd.print(km_3);

digitalWrite(relay, HIGH);

delay(500);

digitalWrite(relay, LOW);

delay(500);

digitalWrite(relay, HIGH);

delay(500);

digitalWrite(relay, LOW);

delay(500);

digitalWrite(relay, HIGH);

delay(2000);

gsm.println("AT+CMGF=1"); //To send SMS in Text Mode

delay(50);

gsm.println("AT+CMGS=\"+251913846366\"\r");// Phone number to be notified

gsm.println("ground fault");// message to be sent

delay(5000);

}

if((200<=Voltage_1 && Voltage_1<=220)&& ( Voltage_2<200) && (200<=Voltage_3 && Voltage_3<=220))

{

lcd.setCursor(0, 0);

lcd.print("Line 1 "); lcd.print("Normal");

lcd.setCursor(0, 1);

lcd.print("Line 2 ");lcd.print("ground fault");

km_2=(0.03*(Voltage_2/Current_2));

lcd.setCursor(0, 3);

lcd.print("km_2");

Serial.println(km_2);

lcd.setCursor(5, 3);

lcd.print(km_2);

digitalWrite(relay, HIGH );

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delay(500);

digitalWrite(relay, LOW);

delay(500);

digitalWrite(relay, HIGH );

delay(500);

digitalWrite(relay, LOW );

delay(500);

digitalWrite(relay, HIGH );

delay(5000);

lcd.setCursor(0, 2);

lcd.print("Line 3 "); lcd.print("Normal");

// gsm.println("AT+CMGF=1"); //To send SMS in Text Mode

delay(50);

//gsm.println("AT+CMGS=\"+251913846366\"\r");// Phone number to be notified

//gsm.println("ground fault");// message to be sent

delay(5000);

}

if(( Voltage_1<200)&& (200<=Voltage_2 && Voltage_2<=220) && (200<=Voltage_3 && Voltage_3<=220))

{

lcd.setCursor(0, 0);

lcd.print("Line 1 "); lcd.print("ground fault");

km_1=(0.03*(Voltage_1/Current_1));

lcd.setCursor(0, 3);lcd.print("km_1");

lcd.setCursor(5, 3);

lcd.print(km_1);

digitalWrite(relay, HIGH );

delay(500);

digitalWrite(relay, LOW);

delay(500);

digitalWrite(relay, HIGH );

delay(500);

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digitalWrite(relay, LOW );

delay(500);

digitalWrite(relay, HIGH );

delay(5000);

Serial.println(km_1);

lcd.setCursor(5, 3);

lcd.print(km_1);

lcd.setCursor(0, 1);

lcd.print("Line 2 ");lcd.print("Normal");

lcd.setCursor(0, 2);

lcd.print("Line 3 "); lcd.print("Normal");

gsm.println("AT+CMGF=1"); //To send SMS in Text Mode

delay(50);

gsm.println("AT+CMGS=\"+251913846366\"\r");// Phone number to be notified

gsm.println("ground fault");// message to be sent

delay(5000);

}

if(( Voltage_1<200)&& ( Voltage_2<200) && (200<=Voltage_3 && Voltage_3<=220))

{

lcd.setCursor(0, 0);

lcd.print("Line 1 "); lcd.print("Short");

km_1=(0.03*(Voltage_1/Current_1));

lcd.setCursor(0, 3);lcd.print("km_1 ");

lcd.setCursor(5, 3);

lcd.print(km_1 );

Serial.println(km_1);

digitalWrite(relay, HIGH );

delay(500);

digitalWrite(relay, LOW);

delay(500);

digitalWrite(relay, HIGH );

Page-79

delay(500);

digitalWrite(relay, LOW );

delay(500);

digitalWrite(relay, HIGH );

delay(5000);

lcd.setCursor(0, 1);

lcd.print("Line 2 ");lcd.print("Short");

lcd.setCursor(0, 2);

lcd.print("Line 3 "); lcd.print("Normal");

gsm.println("AT+CMGF=1"); //To send SMS in Text Mode

delay(50);

gsm.println("AT+CMGS=\"+251913846366\"\r");// Phone number to be notified

gsm.println("Short");// message to be sent

delay(5000);

}

if(( Voltage_1<200)&& (200<=Voltage_2 && Voltage_2<=220) && ( Voltage_3<220))

{

lcd.setCursor(0, 0);

lcd.print("Line 1 "); lcd.print("Short");

km_1=(0.03*(Voltage_1/Current_1));

lcd.setCursor(0, 3);lcd.print("km_1");

lcd.setCursor(5, 3);

lcd.print(km_1);

Serial.println(km_1);

digitalWrite(relay, HIGH );

delay(500);

digitalWrite(relay, LOW);

delay(500);

digitalWrite(relay, HIGH );

delay(500);

digitalWrite(relay, LOW );

Page-80

delay(500);

digitalWrite(relay, HIGH );

delay(5000);

lcd.setCursor(0, 1);

lcd.print("Line 2 ");lcd.print("Normal");

lcd.setCursor(0, 2);

lcd.print("Line 3 "); lcd.print("Short");

gsm.println("AT+CMGF=1"); //To send SMS in Text Mode

delay(50);

gsm.println("AT+CMGS=\"+251913846366\"\r");// Phone number to be notified

gsm.println("Short");// message to be sent

delay(5000);

}

if((200<=Voltage_1 && Voltage_1<=220)&& ( Voltage_2<=200) && ( Voltage_3<200))

{

lcd.setCursor(0, 0);

lcd.print("Line 1 "); lcd.print("Normal");

lcd.print(" ");

lcd.setCursor(0, 1);

lcd.print("Line 2 ");lcd.print("Short");

km_2=(0.03*(Voltage_2/Current_2));

lcd.setCursor(0, 3);

lcd.print("km_2 ");

lcd.setCursor(5, 3);

lcd.print(km_2 );

digitalWrite(relay, HIGH );

delay(500);

digitalWrite(relay, LOW);

delay(500);

digitalWrite(relay, HIGH );

delay(500);

Page-81

digitalWrite(relay, LOW );

delay(500);

digitalWrite(relay, HIGH );

delay(5000);

lcd.setCursor(0, 2);

Serial.println(km_2);

lcd.print("Line 3 "); lcd.print("Short");

gsm.println("AT+CMGF=1"); //To send SMS in Text Mode

delay(50);

gsm.println("AT+CMGS=\"+251913846366\"\r");// Phone number to be notified

gsm.println("Short");// message to be sent

delay(5000);

}

}

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APPEDIX-D table shows Energy consumption and tariff of Ethiopian Electric utility

Page-83

APPENDIX-E Single line diagram of Gumguma line

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