 Open Access
 Total Downloads : 7775
 Authors : Samima Akter, Anulekha Saha, Prof. Priyanath Das
 Paper ID : IJERTV1IS8497
 Volume & Issue : Volume 01, Issue 08 (October 2012)
 Published (First Online): 29102012
 ISSN (Online) : 22780181
 Publisher Name : IJERT
 License: This work is licensed under a Creative Commons Attribution 4.0 International License
Modelling, Simulation and Comparison of Various FACTS Devices in Power System
Samima Akter Anulekha Saha Prof. Priyanath Das
P.G Scholar Ph.D Scholar Associate Professor
Electrical Engineering Department, National Institute of Technology Agartala, Jirania, Tripura (west), Pin – 799055, India.
Abstract
Modelling and simulation of Fixed Capacitor Thyristor Controlled Reactor (FCTCR), Static synchronous compensator (STATCOM), Thyristor controlled Series Capacitor (TCSC), Static synchronous Series Compensator (SSSC) and Unified Power Flow Controller (UPFC) for power system stability enhancement and improvement of power transfer capability have been presented in this paper. First, power flow results are obtained and then power (real and reactive power) profiles have been studied for an uncompensated system and then compared with the results obtained after compensating the system using the abovementioned FACTS devices. The simulation results demonstrate the performance of the system for each of the FACTS devices in improving the power profile and thereby voltage stability of the same. All simulations have been carried out in MATLAB/SIMULINK environment.
Keywords FACTS, real and reactive power, FC TCR, STATCOM, Voltage stability, SSSC, TCSC, power profile, UPFC.

Introduction
Modern power system is complex and it is essential to fulfil the demand with better power quality. Advanced technologies are nowadays being used for improving power system reliability, security and profitability and due to this power quality is improved. Voltage stability, voltage security and power profile improvement are essential for power quality improvement. To achieve optimum performance of power system it is required to control reactive power flow in the network. Construction of new transmission lines and power stations increase the problem of system operation as well as the overall cost. Regulatory limitation on the expansion of system network has resulted in reduction in stability margin thereby increasing the risk of voltage collapse [3]. Voltage collapse occurs in power system when system is faulted, heavily loaded and there is a sudden increase in the demand of reactive power. Voltage instability in power system occurs when the system is unable to meet the reactive power demand.
Reactive power imbalance occur when system is faulted, heavily loaded and voltage fluctuation is there. Reactive power balance can be regained by connecting a device with the transmission line which can inject or absorb reactive power based on system requirement [4].One of the most important reactive power sources is FACTS (Flexible A.C transmission system) device. FACTS may be defined as a power
electronic based semiconductor device which can inject or absorb reactive power in a system as per requirement. This device allows Flexible operation of an AC system without stressing the system. In this paper, performance of FCTCR, STATCOM, TCSC, SSSC and UPFC are analysed.
which helps in controlling the power flow. Shunt type FACTS device are used for controlling and damping voltage oscillations in a power system. The benefits of employing FACTS are many: improvement of the dynamic and transient stability, voltage stability and security improvement, less active and reactive power loss, voltage and power profile improvement, power quality improvement, increasing power flow capability through the transmission line, voltage regulation and efficiency of power system operation improvement, steady state power flow improvement, voltage margin improvement, loss minimization, line capacity and loadability of the system improvement [21]. FACTS controllers are divided into four categories:
Shunt controller: TCSC, TCPAR and SSSC,
Series controller: STATCOM and SVC, Series Series controller IPFC
SeriesShunt controller:UPFC, IPFC etc.
This paper deals with five FACTS devices (FC TCR, STATCOM, TCSC, SSSC and UPFC).

Literature review
Research works are going on in finding newer concept for minimizing the reason of voltage collapse by increasing voltage stability (Dynamic, Transient and Steadystate stability), voltage margin and voltage security in the system. Voltage collapse is a major problem of power system and it occurs due to voltage instability. There are many analysis methods for determining voltage stability based on power flow. Steady state stability is the ability of power system to control after small disturbances e.g.: change in load [4]. In [6], dynamic performance of two area power system with and without UPFC have been studied and compared with other FACTS (Flexible alternating current transmission system) devices. Various types of FACTS controllers and their performance characteristics have been described in [6]. It is essential to analyse voltage stability for a secure power system. Static VAR compensator (SVC) and Thyristor controlled series capacitor (TCSC) increased system stability by placing SVC Flexible AC transmission system controller at different places steady state stability of system can improved [7].
FACTS (Flexible alternating current transmission system) are mainly used for solving instability problems. Recently it has been noted that FACTS controllers can also be used for power flow control and stability enhancement control. Use of FACTS controllers for improving transient stability of a system has been investigated in [8]. Comparison of the
Power electronic controllers were first introduced in HVDC transmission for improving power flow and system stability. There are four types of controllers in FACTS device family. Series controllers are used to inject voltage in series with the line and directly control voltage and current,
performances of shunt capacitor, FCTCR type SVC,and STATCOM using MATLAB/SIMULINK
software has been done in[9]. In [10] the effect of SVC and STATCOM for static voltage stability margin enhancement is studied. Simulation and comparison of various FACTS devices (FCTCR, UPFC) using Program with integrated circuits Emphasis (PSPICE) software has been done in [11] showing power transfer control.
In [12], how FACTS devices are used for power quality improvement and finally improve impedance, current and voltage in improving power system operation have been studied. In [14], modelling and simulation of SSSC multimachine system for power system stability enhancement is studied. In [16] saddle node bifurcation analysis is applied for finding optimal location of SVC and TCSC, power flow is used to evaluate the effect of FACTS device on system loadability.
In this paper modelling and simulation of various FACTS (Flexible alternating current transmission system) devices have been done using MATLAB/SIMULINK software. These FACTS devices (FCTCR, STATCOM, TCSC, SSSC, and
UPFC) are controlled by controlling their source and line impedance value. First we determined the impedance value for better system performance. By varying the value of capacitor of all the above FACTS device models real and reactive power flow through the system is tabulated to find the FACTS device which gives better performance for a particular capacitor value.

Basic description of FACTS devices

Fixed capacitor thyristor controlled reactor (FCTCR)
Figure1: Fixed capacitor thyristor controlled reactor
Static VAR compensated FACTS device are the most important device and have been used for a number of years to improve voltage and power flow
through the transmission line by resolving dynamic voltage problems. SVC is shunt conncted static generator/absorber. Utilities of SVC controller in transmission line are many: a) provides high performance in steadystate and transient voltage stability control, b) dampen power swing, c) reduce system loss, d) Control real and reactive power flow.
Simple FCTCR type SVC configuration is shown in figure 1. In FCTCR,a capacitor is placed in parallel with a thyristor controlled reactor. Is, Ir and Ic are system current, reactor current and capacitor current respectively which flows through the FCTCR circuit. Fixed capacitor Thyristor controlled reactor (FCTCR) can provide continuous lagging and leading VARS to the system [5]. Circulating current through the reactor (Ir) is controlled by controlling the firing angle of backback thyristor valves connected in series with the reactor. Leading var to the system is supplied by the capacitor. For supplying lagging vars to the system, TCR is generally rated larger than the capacitor.

Static synchronous .
compensator(STATCOM)
s
Figure 2: Static synchronous compensator
The static synchronous compensator (STATCOM) is another shunt connected GTO based FACTS device. STATCOM is a static synchronous generator operated as a static VAR compensator which can inject lagging or leading var into the system. STATCOM have several advantages. It has no rotating parts, very fast in response, requires less space as bulky passive components are eliminated, inherently modular and relocatable, less maintenance and no problem as loss of synchronism [5].Simple diagram of STATCOM is shown in figure [2].The dc source voltage is converted into ac voltage by the voltage source converter using GTO and ac voltage is inserted into the line through the transformer. In heavy loaded condition if. Output of VSC is more than the line voltage, converter supplies lagging VARs to the transmission line. During low load condition if line voltage is more than then converter absorbs lagging VAR from the system. If o/p
voltage of converter is equal to line voltage, then the STATCOM is in floating condition and this shunt device does not supply or absorb reactive power to the system or from the system.

Thyristor controlled series capacitor (TCSC)
Figure 3: Thyristor controlled series
capacitor
Thyristor controlled series capacitor (TCSC) is very important series compensator like SSSC. Specially in this FACTS (Flexible alternating transmission system) device, thyristor with gate turnoff capability is not required. Figure 3 shows schematic diagram of a TCSC controller. In TCSC, capacitor is inserted directly into the transmission line and TCR are mounted in parallel with the capacitor. As the capacitor is inserted in series with the line, there is no need of using high voltage transformer and thus it gives better economy. Firing angle of back to back thyristors are controlled to
control the reactor. At 180Â° firing angle TCR, is non conducting and at 90Â° firing angle TCR is in full conduction [4].

Static synchronous series compensator (SSSC)
Figure 4: Static synchronous series compensator
In present days, SSSC is one of the most important FACTS controller used for series compensation of power. In series compensation the capacitor which is connected in series compensates the inductive reactance of the transmission line. SSSC output voltage (Vc) is in quadrature with the line current (I). The voltage across series capacitor is jXcI (where Xc is the capacitive reactance of the series capacitor) and
voltage drop across line inductance (XL) is +jXLI cancel each other thus reducing the effect of line inductance. Due to this, power transfer capability is increased [5].The symbolic representation of SSSC using voltage source converter is shown in figure 4. Supply voltage from a dc source is converted into ac voltage using VSC (voltage source converter). Quadrature voltage is injected into the line through a coupling transformer. This injected voltage (Vc) lags the line current (I) by 90Âºand series compensation is done. SSSC control flow of real and reactive power through the system.

Unified power flow controller (UPFC)
Figure 5: Unified power flow controller
Figure [5] shows a schematic diagram of UPFC. Full form of UPFC is Unified power flow controller. The word unified signifies all parameters (e.g. voltage, phase angle, impedance, real and reactive power and power factor) which effect power flow in the system can be controlled [5]. UPFC is the most modernised device among all the FACTS devices which can be used to enhance steadystate stability, dynamic stability, real and reactive power flow and so on. UPFC consists of two converters. One converter (SSSC) is connected in series with the transmission line and other converter (STATCOM) is connected in parallel with the transmission line. The two converters are coupled through a common dc link which provides bidirectional flow of real power between series o/p SSSC and shunt output STATCOM respectively. For balancing of power between series and shunt controller it is necessary to maintain constant voltage across the dc link. Series branch (SSSC) of the UPFC injects variable magnitude voltage and phase angle. This improves power flow capability and transient stability [6].Shunt branch (STATCOM) maintains the balance between the real power absorption from or injection into the system.


Performance analysis of FACTS devices

Uncompensated system model
Figure 6: Uncompensated System
Figure [6] shows the basic transmission (11kV) model of an uncompensated system. This model consists of current measurement block, voltage measurement block, real and reactive power block and scopes. 11kv voltage is supplied from the AC voltage source to the system. Source impedance (0.01+0.001) , Line impedance (5+0.023) and load is kept constant at 25MW and 50MVAR for the above transmission line model. Simulation is done using MATLAB/SIMULINK. Current measurement block is used to measure the instantaneous source and load current flowing through the transmission line, Voltage measurement block is used to measure the source and load voltage. Real and reactive power in load side is measured using active and reactive power measurement block. Scopes display results after simulation. Above model provides three scopes: one displays the source voltage (V) and source current (I), second one displays real (P) and reactive (Q) power and third one displays load voltage (V1) and load current (I1) after simulation. Real and reactive power flows obtained after simulation are shown in below:
Figure 7: Real power flow
Figure 8: Reactive power flow
Figure 9: Load voltage
Figure 10: Load current
Load voltage is found to be 2.1 kV. Real and reactive power flow is obtained without any compensation. So, in order to keep the system stable,
we have to provide reactive power compensation. In this paper, to get better performance regarding voltage stability, five compensating devices have been studied and comparison has been done to find the device that gives best performance under a given operating condition.
All the plots for the compensated systems have been shown for a particular capacitor value of 350ÂµF.

Compensated system

FCTCR Compensated. The SIMULINK model of FCTCR (SVC) with line voltage of 11KV is shown below:
Figure 11: FCTCR compensated system
Line impedance is kept at (0.01+0.001) and load is fixed at 25MW and 50MVAR. Results obtained after simulation of FCTCR model is shown below:
Figure 12: Real power flow
Figure 13: Reactive power flow
Figure 14: Load Voltage
Figure 15: Load current
Real and reactive powers have been obtained for a fixed value of TCR inductance (100mH) and for different values of the capacitor. Improvement obtained in real and reactive power with changes in capacitor values are tablated below:
Table 1: Variation of power flow with change in capacitance
SL
No
Capacita
nce (ÂµF)
Real power(MW)
Reactive
power (MVAR)
1
50
0.628
0.886
2
200
0.733
1.03
3
350
0.86
1.21
4
500
1.02
1.43
5
600
1.14
1.60
6
800
1.44
2.03
7
1000
1.81
2.56
8
1200
2.22
3.15
9
1400
2.58
3.64
10
1500
2.70
3.80
Thus from the above table we see that power flow through the system increases proportionally with increase in capacitance. Real power varies from 0.628MW to 2.70MW and reactive power varies from 0.886MVAR to 3.80MVAR with variation in capacitance value. In this system results have been obtained by varying the capacitor value from 50 ÂµF to 1500 ÂµF.

STATCOM compensated system
Figure 16: STATCOM compensated system
The above figure shows the compensated model of static synchronous compensator. The model is compensated for various capacitance values. For a particular value of capacitance (350ÂµF) plots for real power (P), reactive power (Q), load voltage (V1) and load current (I1) are shown below:
Figure 17: Real power flow
Figure 18: Reactive power flow
Figure 19: Load voltage
Figure 20: Load current
Figure 21: TCSC compensated system
The above model shows a Thyristor Controlled Series Capacitor connected to the system. In TCSC simulation model, inductor is fixed at 100mH and results are obtained for different capacitor values. Resultsobtainedafter simulation is shown below:
Real and reactive power flows obtained by varying the capacitor value till 1500ÂµF are tabulated below:
Table 2: Variation of power flow with change in capacitance
SL NO
Capacitance
(ÂµF)
Real power
(MW)
Reactive power(MVAR)
1
50
0.60
0.90
2
200
0.73
1.025
3
350
0.85
1.20
4
500
1.0
1.42
5
600
1.135
1.6
6
800
1.43
2.05
7
1000
1.8
2.5
8
1200
2.235
3.12
9
1400
2.6
3.68
10
1500
2.7
3.82
Thus we see that increase in the value of capacitance results in the improvement of both real and reactive power flows thereby compensating the system to a large extent. At capacitance value of 1500ÂµF, compensator injects more real (2.7MW) and reactive (3.82MVAR) power to the system and receiving end voltage obtained is 4.5 kV. At this point STATCOM will inject more reactive power than SVC.

Thyristor controlled series capacitor compensated system. The circuit model used for simulation is shown below:
www.ijert.org
Figure 22: Real power flow
Figure 23: Reactive power flow
Figure 24: Load voltage
7
Figure 21: Load current
Above graphsare plotted when model is simulated with capacitor value 350ÂµF.The plots show the improvement in the load voltage (V1), load current (I1), real power (P) and reactive power (Q) with the incorporation of TCSC in the system. Results obtained for different capacitor values of the controller are tabulated below:
Table 3: Variation of power flow with change in capacitance
SL
No
Capacit ance
(ÂµF)
Real power
(MW)
Reactiv e power
(MVA
R)
1
50
0.57
0.805
2
200
0.66
0.93
3
350
0.772
1.085
4
500
0.91
1.28
5
600
1.02
1.43
6
800
1.27
1.80
7
1000
1.65
2.30
8
1200
2.03
2.85
9
1400
2.52
3.5
10
1500
2.66
3.7
From the above table we can see that increasing the value of capacitance results in continuous compensation of real and reactive power without deterioration. Receiving end voltage improves from 2 kV to 3.8 kV.Voltage profile improves up to a certain point depending on capacitance value.

Static synchronous series compensated system. The model of the SSSC compensated system is shown below:
Figure 22: SSSC compensated system
The above configuration shows the compensated model for Static SynchronousSeries Compensator (SSSC) connected to the system. Real and reactive powers are obtained by varying the value of capacitance connected in series with the line. Plots for power and voltage profiles are shown below:
Figure 23: Real power flow
Figure 28: Reactive power flow
Figure 29: Load voltage
www.ijert.org 8
Figure 30: Load current
Plots for a particular value of capacitance (350 ÂµF) are shown above. Real and reactive power variation with change in capacitance values are tabulated below:
Table 4: Variation of power flow with change in capacitance
SL
No
Capacitan ce(ÂµF)
Real power
(MW)
Reactive power
(MVAR)
1
50
0.025
0.036
2
200
0.985
1.38
3
350
2.08
2.93
4
500
1.65
2.34
5
600
1.40
2.00
6
800
1.13
1.60
7
1000
1.00
1.4
8
1200
0.9
1.28
9
1400
0.85
1.21
10
1500
0.83
1.18
From the above table we can see real and reactive power increases with the introduction of capacitance. But, it is also noted that compensation occurs up to a capacitor value of 350ÂµF only.If the capacitance is increased beyond this point, then real and reactive power both deteriorates. So, better compensation is obtained ata capacitor valueof 350ÂµF for this system.

UPFC compensated system
Figure 31: UPFC compensated system
The above circuit shows the basic model of UPFC (unified power flow controller) connected to the system. Graphs obtained after simulation are shown be
low:
Figure 32: Real power flow
Figure 33: Reactive power flow
Figure 34: Load voltage
Figure 35: Load current
The above graphs show real, reactive and receiving end voltage improvement using compensation. Graphs obtained for a particular value of capacitor rating (350uF) are shown above. Power flows obtained with change in capacitance are tabulated below:
Table 5: Variation of power flow with change in capacitance
S
L No
Capacit ance
(ÂµF)
Real power
( MW)
Reactive power
(MVAR)
1
50
0.0254
0.036
2
200
0.975
1.38
3
350
2.08
2.95
4
500
1.64
2.33
5
600
1.4
1.98
6
800
1.13
1.60
7
1000
1.0
1.40
8
1200
0.91
1.285
9
1400
0.85
1.20
10
1500
0.83
1.17
From the above table, it is seen that both power flows is improved up to a certain limit of capacitance (350ÂµF). In this point injection of real and reactive power to the system is maximum. Beyond this, if we increase the value of capacitance then power profile is deteriorates. So, we can conclude that desirable performance is obtained at capacitor rating 350ÂµF for UPFC compensated system.
4.3. Comparison between all FACTS devices
Table 6: Comparison of power flow between above FACTS Devices
FACTS
Device
Capacitance
(350ÂµF)
Capacitance
(1500ÂµF)
Real power( MW)
Reacti ve power( MVAR
)
Real power( MW)
Reacti ve power( MVAR
)
FCTCR
0.86
1.21
2.70
3.80
STATC
OM
0.85
1.20
2.70
3.82
TCSC
0.772
1.085
2.66
3.70
SSSC
2.08
2.93
0.83
1.18
UPFC
2.08
2.95
0.83
1.17
From the above table, it is seen that reactive power improvement will vary with change in capacitance in all the five cases. At a capacitor value of 350ÂµF UPFC is seen to give best performance and at capacitor value 1500ÂµF, STATCOM gives better performance. Since, increased rating of capacitor means increase the cost of equipment. So, from the above comparison table we can conclude that UPFC FACTS controller will give optimum performance at capacitor rating of 350ÂµF.



Result and discussion
Reactive power, MVAR

FCTCR type SVC compensation:
Capacitance, ÂµF
Figure 36: Variation of power flow with change in capacitance (501500ÂµF)
The above graph shows the variation of reactive power profile with change in capacitance for an FC TCR type SVC connected to the system. Reactive power flows improves proportionally with increase in capacitance value. In this case, optimum performance is obtained for capacitor value of 1500ÂµF.
Reactive power, MVAR

STATCOM Compensation
Capacitance, ÂµF
Figure 37: Variation of power flow with change in capacitance (501500ÂµF)
Above graph shows the variation of reactive power for different capacitor values for a STATCOM connected to the system. Increasing the value of
capacitance result in continuous compensation of reactive power.
5.3.
Reactive power, MVAR
TCSC Compensation
Capacitance, ÂµF
Figure 38: Variation of power flow with change in capacitance (501500ÂµF)
Above graph shows compensation of the system for varying capacitor values when a TCSC is connected to it. We can see that increase in the value of capacitance results in improvement of reactive power. In this case, a capacitor value of 1500ÂµF gives best performance.
Reactive power, MVAR

SSSC Compensation
Capacitance, ÂµF
Figure 39: Variation of power flow with change in capacitance (501500ÂµF)
The above graph [39] shows reactive power improvement after compensating the system using SSSC. It is seen that reactive power improves only up to a certain value of capacitance (350ÂµF) beyond which it deteriorates.
Reactive power, MVAR

UPFC Compensation
Capacitance, ÂµFFigure 40: Variation of power flow with change in capacitance (501500ÂµF)
From the above graph [40] it is clear that reactive power flow is improved impressively up to a capacitor rating of 350ÂµF beyond which it deteriorates.
Reactive power, MVAR



Comparison of power flow between above FACTS devices
Capacitance, ÂµF
Figure 41: Variation of power flow between above FACTS devices with change in
capacitance (501500ÂµF)
The above graph shows the behaviour of all the FACTS devices for different capacitor values. From this graph, it is observed that, of all FACTS devices, UPFC gives best performance for a capacitor value of 350ÂµF after which its performance deteriorates. Again we see, that the performance of STATCOM continues to improve with increasing capacitance. But, increasing the capacitor rating means increasing the overall cost of the equipment. So, after comparing the performances of all the five FACTS devices,it can be concluded that desirable performance is obtained with the addition of UPFC to the system for a capacitor value of around 350 ÂµF, all other parameters remaining unchanged.

Conclusion
MATLAB/SIMULINK environment is used for this comparative study to model and simulate FCTCR type SVC, STATCOM, TCSC, SSSC, and UPFC connected to a simple transmission line. This paper presents performance analysis of all the above FACTS devices and an elaborate comparison between their performances. Power flow and voltage profile are seen to improve with all the compensating devices. Results
show that in case of FCTCR and STATCOM compensation, reactive power flow improves proportionally with increasing capacitance and is maximum at maximum value of capacitance (1500 ÂµF here).In case of TCSC a fixed inductance of 100mH and capacitor value of 1500ÂµF gives best result. For SSSC compensation a capacitor rating of 350ÂµF yields best result. For UPFC, a capacitor rating of 350ÂµF gives bestresults. Voltage compensation using all the FACTS devices have also been studied. UPFC, SSSC and STATCOM,allare found to give desirable performances under given operating conditions. UPFC and SSSC gives their best performance at a capacitor value of 350ÂµF, but UPFC gives the best performance amongst these two.But STATCOM fails to give any impressive performance at this point. However, its performance continues to improve with increase in capacitance and it starts giving better performance than UPFC and SSSC only after its capacitor value is kept around 1200ÂµF. it gives optimum performance at the maximum capacitor value, i.e. 1500ÂµF. FCTCR type SVC provides compensation from a capacitor value as low as 50ÂµF but gives better performance only at a high value of capacitance. Its best performance is achieved at the maximum capacitor value i.e. 1500ÂµF. TCSC behaves in a similar way as SVC and gives best performance at 1500ÂµF. If rating of capacitor is increased then cost of the equipment is also increased. Hence, it can be concluded that UPFC provides most desirable performance when connected to the system as compared to other FACTS devices.

References:

CIGRE, FACTS Overview, IEEE Power Engineering Society, 95 TP 108, April 1995.

N. G Hingorani& Laszlo Gyugyi, Understanding FACTS: concepts and technology of flexible AC transmission System, IEEE Press, New York(2000).

K. R. Padiyar, FACTS controllers in power transmission and distribution,New Age Int. Publisher, 2007.

AbhijitChakrabarti&SunitaHalder, Power System Analysis Operation and Control. Prentice Hall of India Pvt. Limited, New Delhi, 2006.

Dr.B.R.Gupta & Er.Vandana Singhal, Power System Operation and Control, S. Chand Publications.

D. Murali, Dr. M. Rajaram& N. Reka, Comparison of FACTS Devices for Power System Stability Enhancement, International Journal of Computer Applications, Volume8 No.4, October 2010.

Bhavin. M. Patel, Enhancement of Steady State voltage Stability Using SVC and TCSC, National Conference on Recent Trends in Engineering & Technology, 13 14May2011.

Rahul Somalwar and Manish Khemariya, A Review of Enhancement of Transient Stability by FACTS Devices, International Journal of Emerging Technologies in Sciences and Engineering, Vol.5, No.3, Marcp012.

AnulekhaSaha, Priyanath Das and Ajoy Kumar chakraborty, Performance Analysis and Comparison of Various FACTS Devices in Power System,International Journal of Computer Applications, Volume 46 No.15,May2012.

MehrdadAhmadiKamarposhti and MostafaAlinezhad, Comparison of SVC and STATCOM in Static Voltage Stability Margin Enhancement, World Academy of Science, Engineering and Technology 50, 2009.

S. Sankar, S. Balaji&S.Arul, Simulation and Comparison of Various FACTS Devices in Power System, International Journal of Engineering Science and Technology, Vol.2 (4), 2010, 538547.

M.P.Donsion, J.A.Guemes, J.M.Rodriguez, Power Quality Benefits of Utilizing FACTS Devices in Electrical power System, IEEE 2007, 2629.

Sidhartha Panda, Modelling, Simulation and optimal tuning of SSSCbased controller in a multimachine power system, World Journal of Modelling and Simulation, Vol.6 (2010) No.2, pp. 110121, England, UK.

Priyanath Das, SunitaHalder nee Dey, AbhijitChakrabarti and TanayaDutta, A Comparative Study in Improvement of Voltage Security in A MultiBus Power System using STATCOM and SVC, International Conference on Energy, Automation and Signal(ICEAS), 28 30Dec, 2008.

AhadKazemi and BabakBadrezadeh, Modelling and Simulation of SVC and TCSC to Study their Effects on Maximum Loadabilitypoint, EPRI technical report EL 4365, April 1987.

Vatsal J. Patel, C. B. Bhatt, Simulation and Analysis for Real and Reactive Power Control with Series Type FACT Controller, International Journal of Emerging Technology and Advanced Engineering, Volume2, ISSUE 3, March 2012.

S. Meikandasivam, Rajesh Kumar Nema and Shailendra Kumar Jain, Behavioral Study of TCSC DeviceA mat lab/Simulink Implementation, World Academy of Science, Engineering and Technology 45, 2008.

S. Muthukrishnan, Dr. A Nirmal Kumar and G. Murugananth, Modelling and Simulation Five Level Inverter based UPFC System, International Journal of Computer Applications, Volume12No. 11, Jannuary 2011.

Alisha Banga and S. S. Kaushik, Modelling and Simulation of SVC controller for Enhancement of power system stability, International Journal of Advances in Engineering & Technology, Vol.1, Issue 3, pp. 7984, July 2011.

Bindeshwar singh, K.S.Verma, Deependra Singh, C.N.Singh, Archana singh, Ekta Agarwal, Rahul Dixit, Baljiv Tyagi, Introduction of FACTS controllers, a critical review,International Journal of reviews in computing, Vol 8, 31st December 2011.