DYNAMIC HYBRID REACTIVE POWER COMPENSATION (DHRPC) INRADIAL DISTRIBUTION SYSTEM WITH WIND FARMS

ALAHMADI NAJI SALAH

UNIVERSITI TEKNOLOGI MALAYSIA

Replace this page with form PSZ 19:16 (Pind. 1/07), which can beobtained from SPS or your faculty.

Replace this page with the Cooperation Declaration form, which can beobtained from SPS or your faculty.

DYNAMIC HYBRID REACTIVE POWER COMPENSATION (DHRPC) INRADIAL DISTRIBUTION SYSTEM WITH WIND FARMS

ALAHMADI NAJI SALAH

A project report submitted in partial fulfilment of therequirements for the award of the degree ofMaster of Engineering (Electrical-Power)

Faculty of Electrical EngineeringUniversiti Teknologi Malaysia

JANUARY 2013

iii

To my family, especially my parents.....to my beloved wife and son ”YAZAN” Finally

to my first lecturer Prof.Mohammed Alsaeed

iv

ACKNOWLEDGEMENT

In the name of God,the most gracious, the most merciful.I offer my sincerestgratitude to my supervisor, Prof. Ir. Dr Abdullah Asuhaimi bin Mohd.Zin, who hassupported me throughout my research with his patience and knowledge. I attributethe level of my Masters degree to his encouragement and effort and without him thisproject, too, would not have been completed.

Finally, words alone cannot express the special thanks I owe to my mother, mywife and my son for supporting and encouraging me to pursue this degree.

ALAHMADI NAJI SALAH

v

ABSTRACT

As a renewable energy, wind power, most is anticipated to contributed asignificant part of the generation in power systems in the future, but also bring newproblems related to the integration of power quality, consisting mainly of voltagecontrol and reactive power compensation. Wind power generally dose not contributeto voltage control in the system. Induction machines are mostly used as generators inwind power production based. Induction generators used in wind turbines and windfarms consume a large amount of reactive power. Next, since there is no voltage controlof induction machines installed and draw reactive power from the power system,these machines are a source of of voltage fluctuations. Therefore, a combination ofwind turbines for power networks, especially the poor distribution network is oneof the major concerns of power system studies. Reactive power compensation andpower quality in the poor distribution networks to connect the wind turbines are abig task for this thesis.This work was simulated using MATLAB / Simulink for aweak distribution network and the integration of wind power in the network. Withoutreactive power compensation of wind power in the network, the collapse of the systemvoltage and under voltage tripping of wind generators occur. For dynamic reactivepower compensation, as STATCOM (Static Synchronous Compensator) and capacitorsare used at the point of interconnection of wind farms and networks, the system absorbsthe generated wind power while maintaining its voltage level. As a result the studyshows that, reactive power compensation by STATCOM and capacitor banks make itpossible the combination of wind farm in a weak distribution network.

vi

ABSTRAK

Sebagai tenaga boleh diperbaharui yang mungkin, kuasa angin, kebanyakandijangka akan menyumbang sebahagian penjanaan yang ketara dalam sistem kuasapada masa akan datang, tetapi juga membawa masalah baru yang berkaitan integrasiberkualiti kuasa, yang terdiri terutamanya daripada pampasan kawalan voltan dankuasa reaktif. Kuasa angin amnya tidak menyumbang kepada kawalan voltan dalamsistem. Mesin induksi kebanyakannya digunakan sebagai penjana dalam anginpengeluaran penjana kuasa based. Mesin induks yang digunakan dalam turbin angindan ladang angin memakan sejumlah besar kuasa reaktif. Seterusnya, oleh keranatidak ada kawalan voltan mesin induksi yang dipasang dan mengambil kuasa reaktifdaripada sistem kuasa, mesin ini adalah sumber turun naik voltan. Oleh itu, gabunganturbin angin bagi rangkaian kuasa, terutamanya rangkaian agihan lemah merupskansalah satu daripada kebimbangan utama kajian sistem kuasa. Pampasan kuasa reaktifdan kualiti kuasa di rangkaian agihon lemah untuk menyambung turbin angin adalahsatu tugas yang besar untuk thesis. Masalah ini dikaji dengan membuat simulasimenggunakan MATLAB / Simulink bagi rangkaian agihan yang lemah dan integrasikuasa angin dalam rangkaian. Tanpa pampasan kuasa reaktif kuasa angin dalamrangkaian, kejatuhan voltan sistem dan di bawah voltan penyandungan penjana anginberlaku. Bagi pampasan kuasa reaktif yang dinamik, sebagai STATCOM (pemampasSynchronous Statik) dan kapasitor digunakan pada titik sambungtara ladang angin danrangkaian, sistem menyerap kuasa angin yang dihasilkan pada masa yang sama akanmengekalkan tahap voltan. Hasilnya kajian menunjukkan bahawa, pampasan kuasareaktif oleh STATCOM dan bank kapasitor membuat ia memungkinkan gabunganladang angin dalam rangkaian pengedaran yang lemah diadakan.

vii

TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION iiDEDICATION iiiACKNOWLEDGEMENT ivABSTRACT vABSTRAK viTABLE OF CONTENTS viiLIST OF TABLES xLIST OF FIGURES xiLIST OF ABBREVIATIONS xivLIST OF SYMBOLS xviLIST OF APPENDICES xvii

1 INTRODUCTION 11.1 Background 11.2 Electric Power Systems 41.3 Traditional Concepts of Clectrical Power System 51.4 New Concept of Electrical Power System 61.5 Distribution Network 61.6 Power Quality Issues of Wind Farms 61.7 Reactive Power 81.8 Reactive Power (VAr) Compensation 81.9 Problem Statement 91.10 Objectives 91.11 Scope 101.12 Thesis Outline 10

2 LITERATURE REVIEW 112.1 Introduction 112.2 Background and Revision 11

viii

2.3 Power Quality 132.3.1 Steady-State Voltage Magnitude and Frequency 132.3.2 Voltage Sag 142.3.3 Harmonics 152.3.4 Voltage Fluctuations and Flicker 152.3.5 Transient 17

2.4 Wind Power 192.5 Wind Turbine Types 202.6 Wind Turbine Generators 232.7 Synchronous Generators 232.8 The Asynchronous Induction Generators 242.9 The Inductance Machine as Motor 252.10 The Inductance Machine as a Generator 262.11 Capacitor Banks 272.12 Capacitors’ Behavior 272.13 Benefits of Power Factor Correction Capacitors 29

2.13.1 Reduce Power Bills 292.13.2 Gains in System Capacity 292.13.3 Improve Voltage Conditions 292.13.4 Reduce Line Losses 30

2.14 Location of Power Factor Improvement Capacitor Banks: 302.15 Control of Power Flow Based on FACTS Devices 312.16 The Concept of FACTS Devices 332.17 Modelling of FACTS Devices 332.18 Thyristor Controlled Reactor (TCR) 342.19 Thyristor Controlled Reactor (TCR) Devices: 35

2.19.1 Static VAr Compensators (SVC) 352.19.2 Thyristor Controlled Series Capacitor (TCSC) 36

2.20 Synchronous Voltage Source (SVS) 372.21 Synchronous Voltage Source (SVS) 37

2.21.1 Static Synchronous Series Compensator(SSSC) 38

2.21.2 Unified Power Flow Controller (UPFC) 392.21.3 Static Compensator (STATCOM) 40

2.21.3.1 STATCOM Features: 422.21.3.2 STATCOM Implementations 43

2.22 Summary 43

ix

3 RESEARCH METHODOLOGY 443.1 Research-Flow 443.2 Problem Elicitation 443.3 Requirement of Analysis and Data Gathering 443.4 Test System 463.5 Simulation of Test System 473.6 Summary 47

4 RESULTS AND DISCUSSIONS 484.1 Simulation Results 484.2 Simulation Model A 48

4.2.1 Case Study 1 484.2.2 Case Study 2 494.2.3 Case Study 3 514.2.4 Case Study 4 54

4.3 Simulation Model B 574.3.1 Case Study 1 574.3.2 Case Study 2 584.3.3 Case Study 3 604.3.4 Case Study 4 62

4.4 Simulation Model C 654.4.1 Case Study 1 654.4.2 Case Study 2 664.4.3 Case Study 3 684.4.4 Case Study 4 71

4.5 Summary 73

5 CONCLUSION AND FUTURE WORK 745.1 Conclusion 745.2 Future Work Recommendations 75

REFERENCES 76

Appendix A 79

x

LIST OF TABLES

TABLE NO. TITLE PAGE

1.1 Wind Turbine components 3

xi

LIST OF FIGURES

FIGURE NO. TITLE PAGE

1.1 World total installed capacity (MW)against year 11.2 Schematic Diagram of Wind Turbine 21.3 Schematic Diagram of Wind Turbine 31.4 The Structure of Electric Power System 51.5 Traditional Conception of the Electrical Power System 61.6 New Conception of the Electrical Power System 71.7 Radial Distribution System 71.8 Reactive compensation with Wind Turbine 9

2.1 Voltage Sags 152.2 Single-cycle rms voltage fluctuations due to a large dc welder 162.3 Single-cycle rms voltage fluctuations due to a large dc arc furnace 172.4 Capacitor switching transient 182.5 Figure 192.6 Horizontal axis wind turbines (HAWT) are either upwind

machines (a) or downwind machines (b). Vertical axis windturbines (VAWT) except the wind from any direction (c). 20

2.7 Power in the wind per square meter of cross section at 15oC and1 atm 23

2.8 A 3 phase synchronous generator requires DC for the rotorwindings which normally implies that slip rings and brushes arerequired to transfer that current to the rotor from the exciter 24

2.9 The Torque - Slip curve for an inductance motor 262.10 A self excited inductance generator (external capacitors resonate

with the stator inductance causing oscillation at a particularfrequency. Only a single phase is shown) 27

2.11 powers rectangular 282.12 The installation of capacitor in the system 282.13 Thyristor-controlled reactor (TCR) 34

xii

2.14 A graphical illustration of SVC 352.15 Configuration of a phase of the substation installed TCSC Smooth 362.16 Six pulse voltage sourced inverter 372.17 Static Synchronous Series Compensator 382.18 Unified Power Flow Control (UPFC) 392.19 STATCOM and its equivalent circuit 412.20 General arrangement of STATCOM 41

3.1 research-flow 453.2 Single line diagram of a test system 46

4.1 Voltage of connection bus of network without wind farm andDHRPC 49

4.2 Voltage of connection bus of network with wind farm withoutDHRPC 50

4.3 Active power supplied by wind turbine generators 504.4 Reactive power drawn by induction generators 514.5 Voltage of connection bus of network with wind farm and

DHRPC without fault 524.6 Reactive power generated by DHRPC 534.7 Active power supplied by wind turbine generators 534.8 Reactive power drawn induction generators 544.9 Voltage of connection bus of network with wind farm and

DHRPC with fault 554.10 Reactive power generated by DHRPC 554.11 Active power supplied by wind turbine generators 564.12 Reactive power drawn by induction generators 564.13 Voltage of connection bus of network without wind farm and

DHRPC 574.14 Voltage of connection bus of network with wind without

DHRPC 584.15 Active power supplied by wind turbine generators 594.16 Reactive power drawn by induction generators 594.17 Voltage of connection bus of network with wind farm and

DHRPC without fault 604.18 Reactive power generated by DHRPC 614.19 Active power supplied by wind turbine generators 614.20 Active power supplied by wind turbine generators 624.21 Voltage of connection bus of network with wind farm and

DHRPC with fault 63

xiii

4.22 Reactive power generated by DHRPC 634.23 Active power supplied by wind turbine generators 644.24 Reactive power drawn by induction generators 644.25 Voltage of connection bus of network without wind farm and

DHRPC 654.26 Voltage of connection bus of network without wind farm and

DHRPC 664.27 Active power supplied by wind turbine generators 674.28 Reactive power drawn by induction generators 674.29 Voltage of connection bus of network with wind farm and

DHRPC without fault 694.30 Reactive power generated by DHRPC 694.31 Active power supplied by wind turbine generators 704.32 Reactive power drawn by induction generators 704.33 Voltage of connection bus of network with wind farm and

DHRPC with fault 714.34 reactive power generated by DHRPC 724.35 Active power supplied by wind turbine generators 724.36 Reactive power drawn by induction generators 73

A.1 The three phase Simulink model of the test system 79A.2 The three phase Simulink model of the test system of wind farms 80

xiv

LIST OF ABBREVIATIONS

DHRPC – Dynamic Hybrid Reactive Power Compensation

DC – Direct Current

AC – Alternative Current

FACTS – Flexible AC Transmission System

STATCOM – Static Synchronous Compensator

SVR – Static Var Compensator

SSR – Subsynchronous Resonance

SSSC – Static Synchronous Series Compensator

TCR – Thyristor Controlled Reactor

UPFC – Unified Power Flow Controller

VSC – Voltage Source Converter

PWM – Pulse Width Modulation

IGCT – Integrated Gate Commutated Thyristor

IGBT – Insulated Gate Bipolar Transistor

HVDC – High Voltage Direct Current

GTO – Gate Turn-Off Thyristor

IEEE – Institute of Electrical and Electronics Engineers

IEC – International Electrotechnical Commission

HAWT – Horizontal Axis Wind Turbine

VAWT – Vertical Axis Wind Turbine

EHV – Extra High Voltage

UHV – Ultra High Voltage

VAr – Reactive Power

xv

VA – Apparent Power

PF – Power Factor

K.E – Kinetic Energy

–

xvi

LIST OF SYMBOLS

v – speed

M – mass

ρ – density

A – Cross sectional area

m – meter

s – second

kw – kilo watt

HZ – hertz

MW – mega watt

–

xvii

LIST OF APPENDICES

APPENDIX TITLE PAGE

A DIAGRAM 79

CHAPTER 1

INTRODUCTION

1.1 Background

Nowadays, the quality of the electricity supply has become more importantthan in the past. Over the recent years wind power generation is increasing around theworld. Furthermore, wind power energy production is growing continuously becauseof the economical production and environmental impact as illustrated in Figure 1.1.That has posed a challenging to the power distribution networks and their effects arelikely to be more widespread [1].

Figure 1.1: World total installed capacity [MW] against year

One of the problems with the connecting wind power turbine to distribution

2

network is the huge reactive power consumed by generators. The Wind power turbinesare seen as a consumer of reactive power because of the induction generator is used inwind power generation which cause power quality and voltage problems. Typicallywind turbines may cause undesirable voltage on the distribution system due to ofthe varying nature of wind resources. When the wind speeds reach their maximumthe induction machines will also reach the maximum value VAr consumption whichcauses the voltage to reach undesirable level. The main wind farm conversion systemis built from wind turbines, squirrel cage induction generator, gearbox, transformerand reactive source which is a capacitor bank as illustrated in Figure 1.2. [2].

Figure 1.2: Schematic Diagram of Wind Turbine

On the other hand wind turbine components consist of blades, controller,gearbox, generator, nacelles, rotor and tower which is defined in Table 1.1. andillustrated in Figure 1.3 [3].

In addition the conventional squirrel cage induction generator draws reactivepower which is undesirable behaviour for power system especially in the case of weakdistribution system and large turbine. These types of generator causes slow down thevoltage restoration after a voltage collapse which causes the rotor speed and voltage

3

Figure 1.3: Schematic Diagram of Wind Turbine

Table 1.1: Wind Turbine components

Blades Wind turbines usually have three blades. The blades are between 30-50meters.

Controller The controller is placed in the base of the wind turbines and in the nacelles.

Gearbox Gearbox increases the rotational speed of the shaft. Some turbines do nothave a gearbox and so they have direct drive generators.

Generators Wind turbines typically use a single AC generator (induction) that convertsthe mechanical energy into electrical energy.

Nacelles The main components such as the controller, gearbox, generator and shaft arecalled nacelles houses.

Rotor The rotor involves both blades and the hub.

Tower Usually build from tubular steel tower reaching light of 60-80 meters.

4

unstable. The reactive power will be consumed by the generator when the voltagerestores. The generator continues to accelerate and absorb even big amount of reactivepower when the voltage dose not return quickly. This eventually leads to increase inrotor speed and voltage instability. In order to overcome these types of instabilities,shunt capacitor is installed at the generator terminal to compensate its reactive powerconsumption [4].

In order to control the inherent voltage and stability resulting from theinstallation of wind turbines, the use of dynamic hybrid reactive power compensation(DHRPC) is necessary.There are two methods to minimize voltage problems caused bywind turbines connected to the grid, which are the internal and external solutions. Theinternal solution is by using devices placed inside the wind turbines to minimize thevoltage problems. The external solution involves the use of devices outside the windturbines to minimize the voltage problems [2].

A dynamic hybrid reactive power compensation (DHRPC) is used to minimizevoltage problems as external solution.

On the other hand compensation of wind turbines can be classified into twotypes of events, steady state and transient. Voltage quality which involves voltagefluctuation, flicker and harmonic problems is the important thing to be considered fromthe first type. Voltage stability is the second type of event to be considered [2].

The devices are typically used to provide this compensation is shunt capacitorsand FACTS devices.

1.2 Electric Power Systems

Electricity demand is the fastest growing energy demand worldwide. Therise in electricity use is related to the development of countries and surely it can bepredicted to continue as the faster demand keeps increasing. Electric power systemdevelopment worldwide is the world base on centralized generation stations. In thesestations the voltage is stepped up to various levels (HV, EHV and UHV) to be thentransmitted by the transmission system. The voltage after is then steeped downto be distributed by the radial distribution system to the load. Recently a number

5

of influencing features combined to increase the interest in the use of small scalegeneration. The structure of electric power system is illustrated in Figure 1.4 [5, 6].

Figure 1.4: The Structure of Electric Power System

1.3 Traditional Concepts of Clectrical Power System

The large power plants producing electrical energy usually are located closeto the primary energy sources and remote from the consumer canter. The distributionsystem which delivers electricity to the consumers are designed to operate radially .Onthe other hand before the power reaches the final user, it undergoes three stages asillustrated in Figure 1.5 [7].

6

Figure 1.5: Traditional Conception of the Electrical Power System

1.4 New Concept of Electrical Power System

Nowadays, environmental issues, new energy policies, developed technologyand the expansion of the electrical markets and the huge investment cost areencouraging innovations in the electricity generation sector. New technologies allowsmaller sized plants (renewable sources) to generate the electricity via centralizedgeneration or via renewable energy resources, especially wind power. In this conceptthe electricity will be produced closer to the consumer as illustrated in Figure 1.6 [7].

1.5 Distribution Network

Transmission and Distribution network system is used to transport energy fromthe distribution side to consumer side with less losses and minimum power qualityproblems as much as can. Normal configuration of the distribution system is in radialmodel. The radial distribution system is the opposite of a networked system and doesnot provide for other sources of power. The system is designed for power to flow inone-direction only as illustrated in Figure 1.7 [8, 9].

1.6 Power Quality Issues of Wind Farms

Network power quality is affected substantially from injection grid connectedwind turbine. Some wind turbines cause system voltage dips. The startup of individualturbines is typically the problem. Some turbines are able to measure wind velocity and

7

Figure 1.6: New Conception of the Electrical Power System

Figure 1.7: Radial Distribution System

8

do not start generating until the wind reaches a certain speed and a certain duration.By identifying the appropriate condition for the start up the wind turbines can drawhuge reactive current which is similar to the starting current of induction machine. Thestarting current can be 2-3 times the rating of the machine and takes 10 second. Thesignificant voltage dip on the system can be caused by this sudden current. In thiscase the interconnection requirements are applied by utilities that places limits on thedepth, duration and frequency of voltage allowed at the point of common coupling. Ifthe voltage dips may be caused by wind turbines are in excess of the interconnectionrequirements the utility will decide that the wind turbine be de-energized until theproblem is solved [10].

1.7 Reactive Power

Reactive power is defined as the non working power caused by the magnetizingcurrent, required to run & maintain the magnetism in the devices. Reactive powerrequired by inductive loads (induction generators and motors) increases the amount ofapparent power in the distribution system[11]. The increase in reactive and apparentpower causes the decreasing of power factor.

1.8 Reactive Power (VAr) Compensation

VAr compensation is defined as the management of reactive power to developthe AC power system performance. The VAr compensation concept is to embracea wide and diverse field of both system and customer problems, especially relatedto power quality issues, since most of power quality problems can be solved withan appropriate control of reactive power. In general, the problem of reactive powercompensation is observed from two aspects: voltage support and load compensation.In general, voltage support is required to decrease voltage fluctuation at a giventerminal of a transmission line. In load compensation the objectives are to raisethe value of the system power factor, to balance the real power absorbed fromthe AC supply, compensate voltage regulation and to eliminate current harmoniccomponents created by bulky and fluctuating nonlinear industrial loads. Therefore VArcompensation devices are used depending on the particular requirements of a specificapplication in power system as illustrated in Figure 1.8 [11, 12].

9

Figure 1.8: Reactive compensation with Wind Turbine

1.9 Problem Statement

Wind turbines consist of conventional squirrel cage induction generator whichalways consumes reactive power (VAr) that is undesirable for weak system especiallyin the case of large turbines. In general, this type of generator causes slow downthe voltage restoration after a voltage collapse and this can cause the voltage and rotorspeed instability. When the voltage restores, the generator will consume reactive powerwhich causes blocking the voltage restoration. When the voltage does not go backquickly enough to the nominal value, the generator continues to consume also a bigamount of reactive power. This process causes voltage and rotor speed instability if thewind turbines are connected to a weak system.

1.10 Objectives

The objectives are:

(1) To analyze the impact of Dynamic Hybrid Reactive Power Compensation(DHRPC) in a radial distribution system with wind farms within three differentwind speed (low, medium and high).

(2) To study the characteristics of radial distribution system with wind turbinesbefore and after introducing DHRPC

10

(3) To evaluate the effect of the compensation in power quality issues.

1.11 Scope

The general scope is to determine and analyze the impact of DynamicHybrid Reactive Power Compensation (DHRPC) in radial distribution system withWind farms. The hybrid is considered as Shunt Capacitor and Static SynchronousCompensator (STATCOM).The network is represented in appendix A.

1.12 Thesis Outline

This thesis consists of 5 chapter. Chapter 2 presents an overview and revision ofthe previous work of integration between network system and wind farms. In additionit involves and shows the explanation of FACTS device types, wind turbine generatorsand power quality impact. Chapter 3 describes and shows the methodology deployedin this study used. The research method includes using an analytical approach tostudy and simulate three phase radial distribution system from MATLAB/SIMULINKsimulation software is explained in this chapter.Chapter 4 , involves an analysis anda discussion of results which obtained from the simulation model of three-phasesystem using the Simpowersystem blackest software in MATLAB/Simulink.Chapter5 , Conclusion of this research and future work were discussed based on the results.

REFERENCES

1. Ling, L., Xiangjun, Z., Ping, Z., Yunfeng, X. and Guopin, L. Optimization ofReactive Power Compensation in Wind Farms Using Sensitivity Analysis andTabu Algorithm. IEEE. 1–5, 2008.IEEE.

2. Keshmiri, S., Jamehbozorg, A. and Radman, G. Optimum reactive powercompensation regime for radial connected wind turbines. IEEE , 2011. 24–29,.

3. David, A. and Reed, M. Wind Turbines: Industry and Trade Summary, 2009.

4. Shinde, S., Patil, K. and Gandhare, W. Dynamic compensation of reactivepower for integration of wind power in a weak distribution network.IEEE,2009. 1–6.

5. Keane, A. Integration of Distributed Generation. Ph.D. Thesis. 2007.

6. Viawan, F. Voltage control and voltage stability of power distribution systems

in the presence of distributed generation. Chalmers University of Technology.2008.

7. Sarabia, A. Impact of distributed generation on distribution system. Ph.D.Thesis. 2011.

8. Gutierrez, J., Ruiz, J., Saiz, P., Azcarate, I., Leturiondo, L. and Lazkano, A.Power Quality in Grid-Connected Wind Turbines , IEEE Transactions on, 2008.23(1):p.226-233.

9. Lee, C., Chen, L., Tsai, S., Liu, W. and Wu, Y. The impact of SCIG wind farmconnecting into a distribution system. IEEE, 2009. 1–7,.

10. Kehrli, A. and Ross, M. Understanding grid integration issues at wind farmsand solutions using voltage source converter FACTS technology. IEEE. vol.3.2003.IEEE.

11. Dixon, J., Moran, L., Rodriguez, J. and Domke, R. Reactive powercompensation technologies: State-of-the-art review. Proceedings of the IEEE,2005. 93(12): 2144–2164.

12. Sastry, V. and Mulukutla, S. Power Quality: Var Compensation in power

77

System, 2008.

13. Zheng, C. and Kezunovic, M. Distribution system voltage stability analysiswith wind farms integration. IEEE , 2010. 1–6.

14. Chen, W. The electrical engineering handbook. Academic Press. 2005.

15. Rashid, M. Power electronics handbook. Academic Pr. 2001.

16. Vedam, R. and Sarma, M. Power Quality: VAR Compensation in Power

Systems. CRC. 2008.

17. Stones, J. and Collinson, A. Power quality. Power Engineering Journal, 2001.15(2): 58–64.

18. Masters, G. Renewable and efficient electric power systems. Wiley-IEEEPress. 2004.

19. Kubota, H. Wind turbine generator, 2005.

20. Muller, S., Deicke, M. and De Doncker, R. Doubly fed induction generatorsystems for wind turbines. Industry Applications Magazine, IEEE, 2002. 8(3):26–33.

21. Edds, M., Hejdak, W., Houseman, D., Klein, S., Li, F., Li, J., Maibach, P.,Nicolai, T., Patio, J. and Pasupulati, S. Reactive Power Compensation forWind Power Plants, 978-4244-4241-6109/25.00 C 2009, IEEE.

22. www.teknatool.com. Power Factor Correction, 2003.

23. Singh, M. and Gupta, J. Electrical Energy Audit in Textile Plant: A Study,2011,PP 165-167.

24. Kandlawala, M. Investigation of dynamic behavior of power system installed

with STATCOM. Ph.D. Thesis. 2001.

25. Othman, A. Enhancing the Performance of Flexible AC Transmission Systems(FACTS) by Computational Intelligence , 2011.

26. Acha, E. FACTS: modelling and simulation in power networks. John Wileyand Sons Inc. 2004.

27. Li, G., Lie, T., Shrestha, G. and Lo, K. Design and application of co-ordinatedmultiple FACTS controllers. IET, 2000. vol. 147. 112–120 ,.

28. Canizares, C. Power flow and transient stability models of FACTS controllersfor voltage and angle stability studies. IEEE,2000. vol. 2. 1447–1454, vol.2.

29. Leung, H. and Chung, T. Optimal power flow with a versatile FACTScontroller by genetic algorithm approach. IEEE ,2000. vol. 4. 2806–2811

78

vol.4,.

30. Ronner, B., Maibach, P. and Thurnherr, T. Operational experiences ofSTATCOMs for wind parks. Renewable Power Generation, IET, 2009. 3(3):349–357.

31. Daz Gonzlez, F., Martnez Rojas, M., Sumper, A. and Gomis Bellmunt, O.Strategies for reactive power control in wind farms with STATCOM. 2011.

32. Schauder, C., Gernhardt, M., Stacey, E., Lemak, T., Gyugyi, L., Cease, T.and Edris, A. Operation of100 MVAr TVA Statcon. Power Delivery, IEEE

Transactions on, 1997. 12(4): 1805–1811.

33. Grunbaum, R. Voltage source converters for maintaining of power quality andstability in power distribution. IEEE ,2005. 10 pp.–P. 10.

34. Song, Q., Liu, W. and Yuan, Z. Multilevel optimal modulation and dynamiccontrol strategies for STATCOMs using cascaded multilevel inverters. Power

Delivery, IEEE Transactions on, 2007. 22(3): 1937–1946.

35. Reed, G., Paserba, J., Croasdaile, T., Takeda, M., Hamasaki, Y., Aritsuka, T.,Morishima, N., Jochi, S., Iyoda, I. and Nambu, M. The VELCO STATCOMbased transmission system project. IEEE, 2011. vol. 3. 1109–1114 vol.3.

36. Qi, L., Langston, J. and Steurer, M. Applying a STATCOM for stabilityimprovement to an existing wind farm with fixed-speed induction generators.IEEE, 2008. 1–6.

37. Han, C., Huang, A., Baran, M., Bhattacharya, S., Litzenberger, W., Anderson,L., Johnson, A. and Edris, A. STATCOM impact study on the integration ofa large wind farm into a weak loop power system. Energy conversion, IEEE

Transactions on, 2008. 23(1): 226–233.

38. Fadaeinedjad, R., Moschopoulos, G. and Moallem, M. Using STATCOMto mitigate voltage fluctuations due to aerodynamic aspects of wind turbines.IEEE ,2008. 3648–3654,.