INTERNATIONAL JOURNAL OF ELECTRICAL E ... OF SVC...from Jaisalmer to load centers, 2 nos. 400 kV...

International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –

6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 3, May - June (2013), © IAEME

95

APPLICATION OF SVC FOR VOLTAGE CONTROL IN WIND FARM

POWER SYSTEM

Dr. M. P. Sharma Devandra Saini

AEN, RVPNL, Jaipur Asst. Prof., EE Deptt., SIT, Jaipur

Swati Harsh Sarfaraz Nawaz Asst. Prof., EE Deptt.,AICE, Jaipur Associate Prof. Deptt., SKIT, Jaipur

ABSTRACT

Most of wind power plants are installed far away from load centers, hence require

long EHV transmission lines for evacuation system for pooling the power and transmitting to

far off load centers. Wind Power Generation is infirm and variable subject to vagaries of

nature. Due to large variations in wind power generation, power flows on transmission lines

are also vary and accordingly there is a wide variation in power transmission system voltage

from minimum 0.8 pu to maximum 1.20 pu. Due to low & high power system voltages,

transmission lines are tripped resulting constrained in wind power evacuation. In this paper

Static Var Compensator is proposed at wind power plants penetrated power system. In this

paper simulation studies have been carried out to validate the effectiveness of the SVC for

voltage control with the variation in wind power generation. Case studies are carried out on

18-bus Rajasthan power system to demonstrate the performance of the SVC during high and

low wind power generation conditions. Wind power plants penetrated part of Rajasthan

power system has been modeled using Mi-Power power system analysis software designed

by the M/s PRDC Bangalore. Results of tests conducted on the model system in various

possible field conditions are presented and discussed.

I. INTRODUCTION

In Rajasthan, most of wind power plants are concentrated in western part i.e.

Jaisalmer which is far away from load centers. As on 31-3-2013, total 2140 MW capacity

wind power plants are installed in Jaisalmer area. For evacuation of wind power generation

from Jaisalmer to load centers, 2 nos. 400 kV lines, 3 nos. 220 kV lines & 2 nos. 132 kV lines

INTERNATIONAL JOURNAL OF ELECTRICAL ENGINEERING

& TECHNOLOGY (IJEET)

ISSN 0976 – 6545(Print) ISSN 0976 – 6553(Online) Volume 4, Issue 3, May - June (2013), pp. 95-114

© IAEME: www.iaeme.com/ijeet.asp Journal Impact Factor (2013): 5.5028 (Calculated by GISI) www.jifactor.com

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96

have been constructed. There is a huge variations in wind generation i.e. variation is from

zero to maximum generation. Variation in wind power generation on typical days is shown in

following figures:-

Fig-1: HOURLY AVERAGE WIND GENERATION for 15 March, 2013

Fig-2: HOURLY AVERAGE WIND GENERATION for 23 March, 2013



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Fig-3: HOURLY AVERAGE WIND GENERATION for 10 April,2013

Fig-4: HOURLY AVERAGE WIND GENERATION for 15 April, 2013



98

Due to variation in wind power generation, power transmission voltage is fluctuated. Voltage

fluctuations are mainly due to

� Long EHV transmission lines

� Lack of load in western Rajasthan

� Erratic variation in generation pattern

� Wind Generators do not provide the required VAR support

Over-voltage causes over-fluxing in transformers resulting in tripping of transformers. Due to

over voltages, transmission lines also tripped. With the help of FACTS devices, it is possible

to regulate power system voltage with the variation of wind power generation.

II. SVC AND POWER SYSTEM V-I CHARACTERISTICS

SVC V-I Characteristic

SVC composed of a controllable reactor and a fixed capacitor. The composite

characteristic of SVC is derived by adding the individual characteristics of the components.

SVC are defined by the slope reactance when the controlled voltage is within the control

range.

Fig 5: SVC V-I characteristics

The V-I characteristics are described by the following three equations:

Within control range (-Icmax ≤ Isvc ≤ ILmax )

V = Vref + XsL Isvc

When V<Vmin , the SVC will reach its capacitive limit

B= -Bcmax

When Isvc>ILmax , the SVC will reach its inductive limit

B= BLmax



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Power System V-I Characteristic

The system V-I characteristic is determined by considering the Thevenin equivalent

circuit as viewed from the bus whose voltage is to be regulated by the SVC. The Thevenin

impedance in Fig-6 is predominantly an inductive reactance. The corresponding bus voltage

versus reactive current characteristic is shown in fig-7. Bus voltage increases linearly with

capacitive current injection at bus and decreases linearly with inductive current injection at

bus. Fig-8 shows the effect of source voltage on the V-I characteristic of the power system

bus. and Fig-9 shows the system equivalent reactance on the V-I characteristic of the power

system bus

Fig-6 : Thevenin equivalent circuit of HVAC network

Fig-7: Power system bus Voltage-Reactive current characteristic



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Fig-8: Effect of varying source voltage on V-I characteristic of power system bus

Fig-9: Effect of varying system reactance on V-I characteristic of power system bus

Composite SVC-Power System V-I Characteristic

The system characteristic may be expressed as

V = Eth – Xth Is

Where

V = Power system bus voltage

Is = Bus load current

Eth = Source voltage

Xth = System Thevenin reactance

For inductive load current Is is positive and for capacitive load current Is is negative.



101

The SVC characteristic may be expressed as

V = V0 + XSL Is Where

V = Power system bus voltage

Is = SVC current

Vo = SVC reference voltage where net SVC current is zero

XSL = SVC slope reactance

For inductive SVC current Is is positive and for capacitive SVC current Is is

negative. For voltage outside the control range, the ratio V/Is is determined by the ratings of

the inductor and capacitor. The solution of SVC and power system characteristic equations

graphically illustrated in figure 10. Three system characteristics are considered in the figure,

corresponding to three values of the source voltage. The middle characteristic represents the

nominal system conditions and is assummed to intersect the SVC characteristic at Point A

where V = V0 and I = Is . If the system voltage increases by ∆Eth , due to decrease of

system load level, bus voltage V will increase to V1 without an SVC. With the SVC, the

operating point moves to B, by absorbing inductive current I3. Therefore, SVC hold the

voltage V3 instead of V1 without the SVC.

Similarly if the system voltage decreases by ∆Eth , due to increase of system load

level, bus voltage V will decrease to V2 without an SVC. With the SVC, the operating point

moves to C, by injecting capacitive current I4. Therefore, SVC hold the voltage V4 instead of

V2 without the SVC.

Fig10: Graphical solution of SVC operating point for given system conditions



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III. RESPONSE OF SVC DURING LOW VOLTAGE AND HIGH WIND POWER

GENERATION CONDITION

SVC of (+)150/(-)150 MVAR capacity is connected at 400 kV GSS Jaisalmer through

400/33 kV transformer (Bus-19). Due to high wind power generation SVC reference voltage

is set to 1.10 PU. The slope of SVC is 0.09. The purpose of connecting SVC at Bus number

19 is to regulate the voltage at bus number 2 i.e. Jaisalmer 400 kV bus with the increase in

wind power generation. To demonstrate the effect of SVC on voltage and system losses, load

flow studies have been carried out without and with (+)150/(-)150 MVAR SVC at Bus-19 for

various wind power generation schedule. Following four cases have been considered in the

load flow studies:-

S.

No.

Particulars Connected

capacity of

wind power

plants (MW)

Net Wind Power Despatch (MW)

Case-1

(45 % of

IC)

Case-2

(55 % of

IC)

Case-3

(65 % of

IC)

Case-4

(75 % of IC)

1 400 kV GSS

Jaisalmer

1340 603 737 871 1005

2 220 kV GSS

Amarsagar

760 342 408 494 570

3 132 kV GSS

Jaisalmer

40 18 22 26 30

Total 2140 963 1177 1391 1605

OUTPUT OF LOAD FLOW STUDIES

Case-1 : 45 % wind power generation of installed wind farms capacity

Power plots of load flow study without SVC at Bus-19 is placed at fig-11A and Power plots

of LFS with (+)150/(-)150 MVAR SVC at Bus-19 while other conditions remains unchanged

is placed at fig-11B.

Case-2: 55 % wind power generation of installed wind farms capacity










103


Power plots of load flow study without SVC at 400 kV GSS Jaisalmer is placed at fig-14A

and Power plots of LFS with (+)150/(-)150 MVAR SVC at Bus-19 while other conditions

remains unchanged is placed at fig-14B.

EFFECT OF SVC ON POWER SYSTEM VOLTAGE Power system voltage without and with SVC are tabulated in Table-1. With the

increase of wind power generation, transmission voltages are decreased due to increase of

power flow on transmission lines. With SVC fall in transmission voltages are much lesser

than without SVC.

Table-1: Bus voltages (kV) without and with SVC in high wind power generation

condition

S.

No.

Particulars Case-1

(45 % of IC)

Case-2

(55 % of IC)

Case-3

(65 % of IC)

Case-4

(75 % of IC)

Wind Power Generation (MW) 963 1177 1391 1605

A 400 kV bus voltage

1 400 kV GSS

Jaisalmer

Without SVC 401.48 396.19 388.46 377.40

With SVC 406.91 402.76 396.93 388..86

2 400 kV GSS Barmer Without SVC 402 398 392 384

With SVC 405 402 397 390

3 400 kV GSS Rajwest

LTPS

Without SVC 402 398 392 384

With SVC 405 401 397 390

B 220 kV bus voltage

1 400 kV GSS

Jaisalmer

Without SVC 221 217 213 206

With SVC 223 221 217 212

2 400 kV GSS Barmer Without SVC 219 216 212 205

With SVC 222 219 215 210

3 220 kV GSS

Amarsagar

Without SVC 219 216 211 204

With SVC 221 219 215 210

4 220 kV GSS Phalodi Without SVC 202 198 194 187

With SVC 203 200 196 191

5 220 kV GSS Tinwari Without SVC 205 203 202 199

With SVC 205 204 203 201

C 132 kV bus voltage

1 220 kV GSS

Amarsagar

Without SVC 131 129 126 122

With SVC 133 131 129 126

2 220 kV GSS Phalodi Without SVC 115 113 109 105

With SVC 116 114 111 107

3 220 kV GSS Tinwari Without SVC 119 118 117 116

With SVC 119 118 117 116

4 132 kV GSS

Jaisalmer

Without SVC 130 128 125 121

With SVC 131 130 128 126

D SVC Bus voltage Without SVC 33.97 33.52 32.87 31.93

With SVC 34.73 34.43 34.01 33.43

E MVAR loading on

SVC (Capacitive)

Without SVC - - - -

With SVC 57 66 79 98



104

EFFECT OF SVC ON POWER TRANSMISSION LOSSES

Power system voltage without and with SVC for various wind power generation schedules

are tabulated in Table-2.

Table-2: Power System Losses without and with SVC in high wind power generation

condition

S.

No.

Particulars Case-1

(45 % of

IC)

Case-2

(55 % of

IC)

Case-3

(65 % of

IC)

Case-4

(75 % of IC)

1 Wind Power

Generation

(MW)

963 1177 1391 1605

2 Without SVC

Losses (MW)

31.10 43.71 60.14 82.62

3 With SVC Losses

(MW)

30.63 42.88 58.30 78.06

Above tabulated data indicates that with SVC transmission losses are reduced due to increase

of system voltage and decrease of reactive power flow on transmission lines.

Fig.11A: Without SVC at Bus-19 (45 % i.e. 963 MW wind power generation)



105

Fig.11B: With (+) 150/(-)150 MVAR SVC at Bus-19 (45 % i.e. 963 MW wind power

generation)




106

Fig.12B: With (+) 150/(-)150 MVAR SVC at 400 kV GSS Jaisalmer (55 % i.e. 1177

MW wind power generation)




107


generation)

Fig.14A: With SVC at Bus-19 (75 % i.e. 1605 MW wind power generation)



108


generation)

Fig.15: Bus-2 Voltage without and with SVC with variation in wind power generation



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Fig.16: Loading (MVAR) on SVC with variation in wind power generation

IV. EFFECT OF SVC DURING HIGH VOLTAGE AND LOW WIND POWER

GENERATION CONDITION

SVC of (+)150/(-)150 MVAR capacity is connected at 400 kV GSS Jaisalmer through

400/33 kV transformer (Bus-19). Due to low wind power generation SVC reference voltage

is set to 0.90 PU. The slope of SVC is 0.09. The purpose of connecting SVC at Bus number

19 is to regulate the voltage at bus number 2 i.e. Jaisalmer 400 kV bus with the decrease in

wind power generation. To demonstrate the effect of SVC on voltage load flow studies have

been carried out without and with (+)150/(-)150 MVAR SVC at 400 kV GSS Jaisalmer for

various wind power generation schedule. Following two cases have been considered in the

load flow studies:-

S.

No.

Particulars Connected capacity of wind

power plants (MW)

Net Wind Power Despatch

(MW)

Case-1

(35 % of

IC)

Case-2

(25 % of IC)

1 400 kV GSS

Jaisalmer

1340 469 335

2 220 kV GSS

Amarsagar

760 266 190

3 132 kV GSS

Jaisalmer

40 14 10

Total 2140 749 535



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OUTPUT OF LOAD FLOW STUDIES

Case-1 : 35 % wind power generation of installed wind farms capacity

Power plots of load flow study without SVC at Bus-19 is placed at fig-17A and Power plots of

LFS with (+)150/(-)150 MVAR SVC at Bus-19 while other conditions remains unchanged is

placed at fig-17B.


Power plots of load flow study without SVC at Bus-19 is placed at fig-18A and Power plots of

LFS with (+)150/(-)150 MVAR SVC at Bus-19 while other conditions remains unchanged is

placed at fig-18B.

EFFECT OF SVC ON POWER SYSTEM VOLTAGE

Power system voltage without and with SVC are tabulated in Table-3. With the decrease

of wind power generation, transmission voltages are increased due to decrease of power flow on

transmission lines. With SVC rise in transmission voltages are less than without SVC.

Table-3 : Bus voltages (kV) without and with SVC in low wind power generation condition

S.

No.

Particulars Case-1

(35 % of IC)

Case-2

(25 % of IC)

Wind Power Generation (MW) 749 535

A 400 kV bus voltage

1 400 kV GSS Jaisalmer Without SVC 427.04 428.39

With SVC 412.80 414.14

2 400 kV GSS Barmer Without SVC 427 428

With SVC 419 420

3 400 kV GSS Rajwest LTPS Without SVC 426 428

With SVC 419 421

B 220 kV bus voltage

1 400 kV GSS Jaisalmer Without SVC 235 236

With SVC 228 228

2 400 kV GSS Barmer Without SVC 234 235

With SVC 228 229

3 220 kV GSS Amarsagar Without SVC 233 233

With SVC 226 227

4 220 kV GSS Phalodi Without SVC 218 219

With SVC 214 215

5 220 kV GSS Tinwari Without SVC 218 219

With SVC 217 218

C 132 kV bus voltage

1 220 kV GSS Amarsagar Without SVC 140 140

With SVC 136 136

2 220 kV GSS Phalodi Without SVC 125 126

With SVC 123 124

3 220 kV GSS Tinwari Without SVC 127 127

With SVC 126 127

4 132 kV GSS Jaisalmer Without SVC 139 139

With SVC 135 136

D SVC Bus voltage Without SVC 36.13 36.25

With SVC 34.11 34.21

E MVAR loading on SVC

(Inductive)

Without SVC - -

With SVC 158 161



111



generation)



112



generation)



113

V. CONCLUSION

Most of wind power plants are installed far away from load centers. Long EHV

transmission lines are being constructed for evacuation of wind power generation up to load

centers without planning reactive power management and voltage control. Reactive power

management using shunt reactors and shunt capacitors is not successful in wind power plants

penetrated power system due to large & sudden variation in wind power generation. SVC is

able to regulate the power transmission voltage with the variation in wind power generation.

With the help of Static Var Compensator high as well as low transmission voltages can be

controlled. During high power system voltage, SVC absorb reactive power and function as

shunt reactor and there is less rise in system voltage with SVC as compared to without SVC.

During low power system voltage, SVC generates reactive power & function as shunt

capacitor. Therefore, there is less drop in system voltage with SVC as compared without

SVC.

VI. REFERENCE

[1]. N.G. Hingorani and L. Gyugy, Understanding FACTS, Concepts and Technology of

Flexible AC Transmission System. New York: Inst. Elect. Electron. Eng., Inc., 2000.

[2]. J. J. Paserba, D. J. Leonard, N.W. Miller, S. T. Naumann, M. G. Lauby, and F. P. Sener,

“Coordination of a distribution level continuously controlled compensation device with

existing substation equipment for long term var management,” IEEE Trans. Power Del., vol.

9, no. 2, pp.1034–1040, Apr. 1994.

[3]. K. M. Son, K. S. Moon, S. K. Lee, and J. K. Park, “Coordination of an SVC with a

ULTC reserving compensation margin for emergency control,” IEEE Trans. Power Del., vol.

15, no. 4, pp. 1193–1198, Oct. 2000.

[4]. Task Force no. 2 on Static Var Compensators, Static Var Compensators (1986).

[5]. IEEE Special Stability Controls Working Group, “Static var compensator models for

power flow and dynamic performance simulation,” IEEE Trans. Power Syst., vol. 9, no. 1,

pp. 229–240, Feb. 1994.

[6]. R.A. Schlueter, ,A voltage stability security assessment method,” IEEE Trans. on Power

Systems, vol. 13, no. 4, November 1998, pp. 1423- 1438.

[7]. D. Jovcic, Pahalawaththa, N., Zavahir, M. & Hassan, H.A. (2003) “SVC Dynamic

analytical Model”_ IEEE Trans. On Power Delivery, Vol. 18, No. 4, (October), pp. 1455 -

1461.

[8]. FACTS Controllers in Power Transmission and Distribution By- K.R. Padiyar.

[9] Ameer H. Abd and D.S.Chavan, “Impact of Wind Farm of Double-Fed Induction

Generator (Dfig) on Voltage Quality”, International Journal of Electrical Engineering &

Technology (IJEET), Volume 3, Issue 1, 2012, pp. 235 - 246, ISSN Print : 0976-6545,

ISSN Online: 0976-6553.

[10] Dr. M. P. Sharma and Sarfaraz Nawaz, “Understanding Operation of Shunt Capacitors

and Oltc for Transmission Loss Reduction”, International Journal of Electrical Engineering &

Technology (IJEET), Volume 4, Issue 2, 2013, pp. 344 - 357, ISSN Print : 0976-6545,

ISSN Online: 0976-6553.

[11] T. Nageswara Prasad, V. Chandra Jagan Mohan and Dr. V.C. Veera Reddy, “Shunt

Compensator for Integration of Wind Farm to Polluted Distribution System”, International

Journal of Electrical Engineering & Technology (IJEET), Volume 3, Issue 3, 2012,

pp. 89 - 101, ISSN Print : 0976-6545, ISSN Online: 0976-6553.



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BIOGRAPHIES

Dr. M. P. Sharma received the B.E. degree in Electrical Engineering in 1996 Govt.

Engineering College, Kota, Rajasthan and M. E. degree in Power Systems in 2001 and Ph.D.

degree in 2009 from Malaviya Regional Engineering College, Jaipur (Now name as MNIT).

He is presently working as Assistant Engineer, Rajasthan Rajya Vidhyut Prasaran Nigam

Ltd., Jaipur. He is involved in the system studies of Rajasthan power system for development

of power transmission system in Rajasthan and planning of the power evacuation system for

new power plants. His research interest includes Reactive Power Optimization, Power

System Stability, reduction of T&D losses and protection of power system.(email:

[email protected])

Devendra Saini received the B.Tech. degree in electrical engineering from Rajasthan

Technical University, Kota, in 2011. He is currently pursuing the M.Tech.degree in Power

System from the Jodhpur National University ,Jodhpur. He is currently an Assistant Professor

at the Electrical Engi. Dept. Shankara Institute Of Technology , Jaipur ,Rajasthan. His

research interests are in the areas of FACTS power system problems, controls and transient

stability (email :[email protected])

Swati Harsh has received her B.E. degree from University of Rajasthan. She is currently

working as Assistant professor in department of Electrical Engineering at Anand

International College of Engineering. She is currently pursuing M.Tech. (Power System)

from Swami Keshvanand Institute of Technology, Management and Gramothan (SKIT)

(email: [email protected])

Sarfaraz Nawaz has received his B.E. degree from University of Rajasthan and M.Tech.

degree from MNIT, Jaipur. His research interests include power systems and power

electronics. He is currently an Associate Professor of the Electrical Engg. Dept., Swami

Keshvanand Institute of Technology, Management and Gramothan (SKIT) , Jaipur,

Rajasthan. (email: [email protected])

INTERNATIONAL JOURNAL OF ELECTRICAL E ... OF SVC...from Jaisalmer to load centers, 2 nos. 400 kV...

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