International Journal of Electrical and Electronics
Engineering Research (IJEEER)
ISSN 2250-155X
Vol. 3, Issue 3, Aug 2013, 229-240
© TJPRC Pvt. Ltd.
COORDINATION OF AN SVC WITH THE SHUNT REACTORS AND CAPACITORS
RESERVING COMPENSATION MARGIN FOR EMERGENCY CONTROL
DEVANDRA SAINI1, M. P. SHARMA2 & MANSINGH MEENA3
1
Assistant Professor, Department of Electrical Engineering, SIT, Jaipur, Rajasthan, India
2
Assistant Engineer, RVPNL, Jaipur, Rajasthan, India
3
Assistant Professor, Department of Electrical Engineering, GIT, Jaipur, Rajasthan, India
ABSTRACT
This paper proposes a coordinated control scheme of an SVC, shunt capacitors & shunt reactors of the power
system to get larger operating margin of SVC for emergency control. The conventional method can cause the lack of
operating margin of SVC in some condition. It, however, is important to secure an operating margin for emergency. In the
proposed coordinated control system, SVC control the voltage and operation of shunt capacitors & shunt reactors carried
out depending on loading on SVC. In this paper simulation studies have been carried out to validate the effectiveness of the
proposed method in capacitive as well as inductive loading on SVC. Case studies are carried out on 18-bus Rajasthan
power system to demonstrate the performance of the proposed method. Wind power plants penetrated part of Rajasthan
power system have been modelled using Mi-Power power system analysis software which has been developed by the M/s
PRDC Bangalore. Results of tests conducted on the model system in various possible field conditions are presented and
discussed.
KEYWORDS: Shunt Capacitor Banks (SCB), Coordinated Control, Emergency Control, Operating Margin, SVC (Static
Var Compensator)
INTRODUCTION
Shunt capacitor banks (SCBs) are used in the electrical industry for power factor correction and voltage support.
Shunt capacitors are installed at 33 kV, 11 kV & 0.415 kV voltage level. With the compensation of load inductive reactive
power demand by shunt capacitors, reactive power flow on transmission lines reduce, resulting increase of transmission
level voltage also. Shunt Capacitors are manually switched ON & switched OFF depending on the load bus power factor. If
load bus power factor is lagging then shunt capacitor banks are swiched ON and switched OFF, If load bus power factor is
leading. Shunt reactors are installed at 220 kV & 400 kV voltage level to control the transmission voltage. Shunt reactors
are installed at a bus as well as on long lines at line ends. Shunt reactors reduce the transmission voltage by absorbing the
lightly loaded transmission lines charging MVAR. Bus type shunt reactors are switched ON & switched OFF on the basis
of bus voltage.
SVC are installed in power system to control the power system voltage. SVC can be used for both inductive and
capacitive compensation. In high power system voltage condition, SVC is in inductive mode and loading of SVC depends
upon power system voltage. Inductive loading on SVC increase with the increase of power system voltage. In low power
system voltage condition, SVC is in capacitive mode and loading of SVC depends upon power system voltage. Capacitive
loading on SVC increase with the decrease of power system voltage. Since SVC has a fast dynamic characteristic, it
responds to the electric load demand variation before manually operatin of shunt capacitors and shunt reactors. As a result,
230
Devandra Saini, M. P. Sharma & Mansingh Meena
if the capacity of SVC is sufficient to cope with the variation of the voltage, power system operators do not operate the
shunt reactors and shunt capaciors.
As a result, the SVC cannot have a margin for controlling emergency. Based on the above observations, this paper
proposes a coordinated operation of an SVC, shunt capacitors and shunt reactors to reserve the operating margin of the
SVC for emergency control while improving the load voltage quality.
COMPOSITE SVC AND POWER SYSTEM V-I CHARACTERISTICS
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. 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 I s 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 1. 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 and increase of source voltage due to switching operation of shunt capacitors and shunt reactors, 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 and increase of source voltage due to switching operation of shunt capacitors and
shunt reactors, 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.
Coordination of an SVC with the Shunt Reactors and Capacitors
Reserving Compensation Margin for Emergency Control
231
Figure 1: Graphical Solution of SVC Operating Point for Given System Conditions
PROPOSED METHODLOGY TO INCREASE THE OPERATING MARGIN OF SVC FOR
EMERGENCY CONTROL
From the SVC V-I characteristic, following points are observed :
Capacitive loading on SVC is reduced with increase of SVC bus voltage

Inductive loading on SVC is reduced with decrease of SVC bus voltage
Therefore, to increase the operating margin of SVC for emergency control, following methodlogy is proposed :-

In capacitive loading on SVC, system operator should get switched OFF shunt reactors and switched ON shunt
capacitors in the vicinity of SVC.

In inductive loading on SVC, system operator should get switched ON shunt reactors and switched OFF shunt
capacitors in the vicinity of SVC.
SIMULATION RESULTS OF COORDINATION OF SVC WITH SHUNT REACTORS AND
CAPACITORS IN CAPACITIVE MODE CONDITION OF SVC
Case studies are carried out on 18-bus Rajasthan power system to demonstrate the performance of the proposed
methodology in capacitive mode operation of SVC.Wind power plants penetrated part of Rajasthan power system, placed
at Figure 2, have been modelled using Mi-Power power system analysis software which has been developed by the M/s
PRDC Bangalore. SVC of (+)150/(-)150 MVAR capacity is connected at Bus-19. Due to high wind power generation &
low system voltages, SVC reference voltage is set to 1.10 PU. The purpose of connecting SVC at Bus number 19 is
regulate the voltage at bus number 2 i.e. Jaisalmer 400 kV bus. To investigate the effect of coordinated operation of SVC,
shunt capacitors & shunt reactors under capacitive mode opeartion on
o
Operating margin of SVC
o
Power System Voltage
o
System losses
Load flow studies have been carried for different ON & OFF status of shunt capacitors and shunt reactors
connected in power system as per following table-1
232
Devandra Saini, M. P. Sharma & Mansingh Meena
Table 1: ON & OFF Status of Shunt Capacitors and Shunt Reactors
Connected in Power System in Capacitive Mode Condition of SVC
S.
No.
Particulars
1
2
3
4
5
6
7
8
9
Shunt Reactor at Bus 2
Shunt Reactor at Bus 6
Shunt Capacitor at Bus 12
Shunt Capacitor at Bus 13
Shunt Capacitor at Bus 14
Shunt Capacitor at Bus 15
Shunt Capacitor at Bus 16
Shunt Capacitor at Bus 17
Shunt Capacitor at Bus 18
Capacity of Shunt
Reactors & Shunt
Capacitors (MVAR)
50
20
21.72
10.86
10.86
10.86
21.72
21.72
21.72
CaseI
CaseII
CaseIII
CaseIV
ON
ON
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
ON
ON
ON
ON
ON
ON
ON
ON
OFF
OFF
ON
ON
ON
ON
ON
ON
ON
Power plots of load flow study of above four cases are placed at Figure 2 to Figure 5. Impact of coordinated
operation of SVC, shunt reactors and shunt capacitors on SVC loading in capacitive mode operation of SVC is analyzed in
the following paragraphs
IMPACT ON SVC LOADING
Table 2: Impact of Coordinated Operation of SVC, Shunt Reactor and
Shunt Capacitors on SVC Loading in Capacitive Mode Operation of SVC
S. No.
1
2
3
4
Particulars
Bus-2 Voltage (kV)
Bus-19 (SVC Bus) voltage (kV)
MVAR loading on SVC (Capacitive)
Swing Bus loading (MVAR) (Injection)
Case-I
375.02
32.56
124
1369
Case-II
382.40
32.92
114
1261
Case-III
383.67
32.98
112
1181
Case-IV
391.01
33.34
100
1073
IMPACT ON POWER TRANSMISSION LOSSES
Table 3: Impact of Coordinated Operation of SVC, Shunt Reactor and
Shunt Capacitors on Power Transmission Losses
S. No.
1
Particulars
Transmission losses (MW)
Case-I
86.67
Case-II
82.03
Case-III
78.77
Case-IV
74.76
OBSERVATIONS
Above tabulated data indicates that with coordinated operation of SVC, shunt reactors and shunt capacitors :
Due to switching OFF shunt reactors, 400 kV voltage of Bus-2 has been increased from 375.02 kV to 382.40 kV
in Case-II as compared to Case-I. Due to increase of voltage of Bus-2, SVC bus voltage has also been increased
from 32.56 kV to 32.92 kV in Case-II as compared to Case-I. Due to increase of SVC bus voltage, capacitive
loading on SVC has been reduced from 124 MVAR to 114 MVAR in Case-II as compared to Case-I. Therefore,
operating margin on SVC has been increased from 26 MVAR to 36 MVAR in Case-II as compared to Case-I.

Due to switching ON shunt capacitors, 400 kV voltage of Bus-2 has been increased from 375.02 kV to 383.67 kV
in Case-III as compared to Case-I. Due to increase of voltage of Bus-2, SVC bus voltage has also been increased
from 32.56 kV to 32.98 kV in Case-III as compared to Case-I. Due to increase of SVC bus voltage, capacitive
loading on SVC has been reduced from 124 MVAR to 112 MVAR in Case-III as compared to Case-I. Therefore,
operating margin on SVC has been increased from 26 MVAR to 38 MVAR in Case-III as compared to Case-I.

Due to switching OFF shunt reactors & switching ON shunt capacitors, 400 kV voltage of Bus-2 has been
Coordination of an SVC with the Shunt Reactors and Capacitors
Reserving Compensation Margin for Emergency Control
233
increased from 375.02 kV to 391.01 kV in Case-IVas compared to Case-I. Due to increase of voltage of Bus-2,
SVC bus voltage has also been increased from 32.56 kV to 33.56 kV in Case-IV as compared to Case-I. Due to
increase of SVC bus voltage, capacitive loading on SVC has been reduced from 124 MVAR to 100 MVAR in
Case-IV as compared to Case-I. Therefore, operating margin on SVC has been increased from 26 MVAR to 50
MVAR in Case-IV as compared to Case-I.

Transmission losses have also been reduced from 86.67 MW to 74.76 MW in Case-IV as compared to Case-I.
Therefore, a saving of 11.91 MW (450.67 Lus/annum) in transmission losses has been envisaged in Case-IV as
compared to Case-I.
Figure 2: Case 1 Shunt Reactors ON and Shunt Capacitors OFF in Capacitive Mode of SVC
Figure 3: Case II Shunt Reactors OFF and Shunt Capacitors OFF in Capacitive Mode of SVC
234
Devandra Saini, M. P. Sharma & Mansingh Meena
Figure 4: Case III Shunt Reactors ON and Shunt Capacitors ON in Capacitive Mode of SVC
Figure 5: Case IV Shunt Reactors ON and Shunt Capacitors ON in Capacitive Mode of SVC
SIMULATION RESULTS OF COORDINATION OF SVC WITH SHUNT REACTORS AND
CAPACITORS IN INDUCTIVE MODE CONDITION OF SVC
Case studies are carried out on 18-bus Rajasthan power system to demonstrate the performance of the proposed
method in inductive mode operation of SVC. Wind power plants penetrated part of Rajasthan power system have been
modelled, placed at figure 6, using Mi-Power power system analysis software which has been developed by the M/s PRDC
Bangalore. SVC of (+)150/(-)150 MVAR capacity is connected at Bus-19. Due to low wind power generation & high
235
Coordination of an SVC with the Shunt Reactors and Capacitors
Reserving Compensation Margin for Emergency Control
system voltages, SVC reference voltage is set to 0.90 PU. The purpose of connecting SVC at Bus number 19 is regulate the
voltage at bus number 2 i.e. Jaisalmer 400 kV bus. To investigate the effect of coordinated operation of SVC, shunt
capacitors & shunt reactors under inductive mode opeartion on
o
Operating margin of SVC
o
Power System Voltage
Load flow studies have been carried for different ON & OFF status of shunt capacitors and shunt reactors
connected in power system as per following table-4
Table 4: ON & OFF Status of Shunt Capacitors and Shunt Reactors
Connected in Power System in Inductive Mode Condition of SVC
S.
No.
Particulars
1
2
3
4
5
6
7
8
9
Shunt Reactor at Bus 2
Shunt Reactor at Bus 6
Shunt Capacitor at Bus 12
Shunt Capacitor at Bus 13
Shunt Capacitor at Bus 14
Shunt Capacitor at Bus 15
Shunt Capacitor at Bus 16
Shunt Capacitor at Bus 17
Shunt Capacitor at Bus 18
Capacity of Shunt
Reactors & Shunt
Capacitors (MVAR)
50
20
21.72
10.86
10.86
10.86
21.72
21.72
21.72
CaseV
CaseVI
CaseVII
CaseVIII
OFF
OFF
ON
ON
ON
ON
ON
ON
ON
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
OFF
OFF
OFF
OFF
OFF
OFF
OFF
Power plots of load flow study of above four cases are placed at Figure 6 to Figure 9. Impact of coordinated
operation of SVC, shunt reactors and shunt capacitors on SVC loading in inductive mode operation of SVC is analyzed in
the following paragraphs
IMPACT ON SVC LOADING
Table 5: Impact of Coordinated Operation of SVC, Shunt Reactor and
Shunt Capacitors on SVC Loading in Inductive Mode Operation of SVC
S. No.
1
2
3
Particulars
Bus-2 Voltage (kV)
Bus-19 (SVC Bus) voltage (kV)
MVAR loading on SVC (Inductive)
Case-V
422.77
33.70
138
Case-VI
417.05
33.40
126
Case-VII
417.22
33.41
126
Case-VIII
411.66
33.12
116
OBSERVATIONS
Above tabulated data indicates that with coordinated operation of SVC, shunt reactors and shunt capacitors :
Due to switching OFF shunt capacitors, 400 kV voltage of Bus-2 has been reduced from 422.77 kV to 417.05 kV
in Case-VI as compared to Case-V. Due to decrease of voltage of Bus-2, SVC bus voltage has also been decrased
from 33.70 kV to 33.40 kV in Case-VI as compared to Case-V. Due to decrease of SVC bus voltage, inductive
loading on SVC has been reduced from 138 MVAR to 126 MVAR in Case-VI as compared to Case-V. Therefore,
operating margin on SVC has been increased from 12 MVAR to 24 MVAR in Case-VI as compared to Case-V.

Due to switching ON shunt reactors, 400 kV voltage of Bus-2 has been reduced from 422.77 kV to 417.22 kV in
Case-VII as compared to Case-V. Due to decrease of voltage of Bus-2, SVC bus voltage has also been decrased
from 33.70 kV to 33.41 kV in Case-VII as compared to Case-V. Due to decraese of SVC bus voltage, inductive
loading on SVC has been reduced from 138 MVAR to 126 MVAR in Case-VII as compared to Case-V.
236
Devandra Saini, M. P. Sharma & Mansingh Meena
Therefore, operating margin on SVC has been increased from 12 MVAR to 24 MVAR in Case-VII as compared
to Case-V.

Due to switching OFF shunt capacitors and switching ON shunt reactors, 400 kV voltage of Bus-2 has been
reduced from 422.77 kV to 411.66 kV in Case-VIII as compared to Case-V. Due to decrease of voltage of Bus-2,
SVC bus voltage has also been decrased from 33.70 kV to 33.12 kV in Case-VIII as compared to Case-V. Due to
decraese of SVC bus voltage, inductive loading on SVC has been reduced from 138 MVAR to 116 MVAR in
Case-VIII as compared to Case-V. Therefore, operating margin on SVC has been increased from 12 MVAR to 34
MVAR in Case-VIII as compared to Case-V.
Figure 6: Case V Shunt Reactors OFF and Shunt Capacitors ON in Inductive Mode of SVC
Figure 7: Case VI Shunt Reactors OFF and Shunt Capacitors OFF in Inductive Mode of SVC
Coordination of an SVC with the Shunt Reactors and Capacitors
Reserving Compensation Margin for Emergency Control
237
Figure 8: Case VII Shunt Reactors ON and Shunt Capacitors ON in Inductive Mode of SVC
Figure 9: Case VIII Shunt Reactors ON and Shunt Capacitors OFF in Inductive Mode of SVC
CONCLUSIONS
To increase the operating margin of SVC for emergency control, following methodlogy is proposed

In capacitive loading on SVC, system operator should get switched OFF shunt reactors and switched ON shunt
capacitors in the vicinity of SVC.

In inductive loading on SVC, system operator should get switched ON shunt reactors and switched OFF shunt
capacitors in the vicinity of SVC.
238
Devandra Saini, M. P. Sharma & Mansingh Meena
ACKNOWLEDGEMENTS
Authors are greatful to M/s PRDC, Bangalore to allow use of MiPower Software to carried out this research work.
REFERENCES
1.
"APPLICATION OF SVC FOR VOLTAGE CONTROL IN WIND FARM POWER SYSTEM” By Dr. M.P.
Sharma, Devandra Saini, Swati Harsh, Sarfaraz Nawaz, International Journal of Electrical Engineering &
Technology (IJEET), Volume 4, Issue 3, May-June (2013), pp. 95-114, ISSN Print : 0976-6545, ISSN Online:
0976-6553.
2.
N.G. Hingorani and L. Gyugy, Understanding FACTS, Concepts and Technology of Flexible AC Transmission
System. New York: Inst. Elect. Electron. Eng., Inc., 2000.
3.
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.
4.
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.
5.
Task Force no. 2 on Static Var Compensators, Static Var Compensators (1986).
6.
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.
7.
R.A. Schlueter, ,A voltage stability security assessment method,” IEEE Trans. on Power Systems, vol. 13, no. 4,
November 1998, pp. 1423- 1438.
8.
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.
9.
FACTS Controllers in Power Transmission and Distribution By- K.R. Padiyar.
AUTHOR’S DETAILS
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.
Coordination of an SVC with the Shunt Reactors and Capacitors
Reserving Compensation Margin for Emergency Control
239
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 Reactive
Power Optimization, Power System Stability, reduction of T&D losses and protection of power system.
Mansingh Meena received the B.Tech. degree in electrical engineering from Rajasthan Technical University,
Kota, in 2010. He is currently pursuing the M.Tech.degree in Power System from the Jagan Nath University, Jaipur. He is
currently an Assistant Professor at the Global Institute of Technology, Jaipur, Rajasthan.