International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, Volume 2, Issue 3, March 2012)
Modelling and Analysis of TCSC Controller For
Enhancement of Transmission Network
J. V. Kadia1, J. G. Jamnani2
1, 2
Department of Electrical Engineering
Institute of Technology, Nirma University
Ahmedabad, Gujarat
1
2
jiksh111@gmail.com
jg.jamnani@nirmauni.ac.in
Also TCSC helps increasing the power transfer and
maintain the power system stability by improving the load
angle. In this paper, EHV transmission line with TCSC has
been modeled in the software package PSCADV4.2 various
parameters of transmission lines like power transfer
capability, sending end voltage, receiving end voltage have
been analyzed.
Abstract— The method of series compensation is used since
long back for improvement of power transfer capability of
transmission line with the development of power electronics
devices and control engineering TCSC becomes a multitasking
controller to improve overall characteristic of an electrical
power network in normal as well as faulty condition. In this
paper, TCSC controller has been modeled and its
performance has been analyzed for various events such as
fault on long transmission line, sub synchronous resonance.
The behavior of TCSC is analyzed for open and close loop
modes. The results are verified by different power system
parameter values using software package PSCAD 4.2.
In this paper, the concept of series FACTS controller
like TCSC is discussed. In section II, the typical data of
transmission line parameters are given. In section III, the
conceptual and mathematical model of TCSC is described.
In section IV, the transmission line using series
compensation is model in PSCAD software package. Also
the results of TCSC in open loop and close loop conditions
are discussed. In section V, the comparison results of
different conditions like open loop and close loop for TCSC
are discussed.
Keywords- FACTS, Thyristor Controlled Series Capacitor
(TCSC), Real Power, Sending End Current, Receiving End
Voltage.
II. SYSTEM DESCRIPTION
I. INTRODUCTION
The Transmission line model situated between Kanpur
to Ballabhgard in India. The 3-phase, 400kV, 400km long
transmission line having a load of 400MW is considered in
Figure 1. The transmission line having a resistance of
0.0032 Ω/km and reactance of 1.044 mH/km. [3] the
transmission line modeled in software package PSCAD
V4.2. 3-phase voltage source having a capacity of 11kV are
fed to the step up transformer which increase the voltage
level up to 400kV. Here, the transmission line is divided in
to the three sections each having a length of 100km long.
The fixed load of 400MW connected at the end of
transmission line. Real and reactive power meter are used to
measurement of real and reactive power at the receiving end
side. Fault logic used to show the affected parameter of
transmission line during the fault events.
The concept of FACTS (Flexible Alternating Current
Transmission Systems) was proposed by EPRI (Electric
Power Research Institute) in the mid of 1980s. The main
problem with mechanical devices is that control cannot be
initiated frequently, at that time the FACTS technology
gives new opportunities for controlling power. FACTS
controllers are used to control the interrelated parameters
that govern the operation of transmission system such as
series impedance, shunt impedance, current, voltage, phase
angle. Further the damping of small signal oscillations can
also be achieved. The compensation is done using FACTS
technology, viz. Thyristor Controlled Series Capacitor
(TCSC). TCSC provides a wide range of compensation by
changing the angle and also limits the fault current in case
of faults. In inductive mode TCSC provide protection
against various kinds of faults.
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International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, Volume 2, Issue 3, March 2012)
The real power, sending end voltage, receiving end
current of uncompensated transmission line during LLLG
fault occurs at 1 sec shown in fig2. At the fault point the
real power of uncompensated line decreases and after the
fault cleared power increases to maintain the value before
faults. After the faults the real power oscillated some time
that indicated the stability of system not maintain. The
magnitude of receiving end voltage decreases that indicates
the voltage drop on transmission line and the current of
transmission line are increases 1.5 to 2 times of
fundamental current.
Figure 1. Model of Uncompensated Transmission Line in PSCAD.
Figure 2(a).
Active Power.
Figure 2(b).
Receiving End Voltage.
III. MODELLING OF TCSC
Thyristor controlled series compensator (TCSC) device is
a series compensator to govern the power flow by
compensating the reactance of transmission line. Both
capacitive and inductive reactance compensation are
possible by proper selection of capacitor and inductor values
of the TCSC device which can be realized through reactance
equation. A TCSC which consist of a series compensating
capacitor(C) shunted by a Thyristor controlled reactor
(TCR). TCR is a variable inductive reactor (XL ()) tuned at
firing angle. The variation of XL with respect to  can be
given as (1, 2) [3]-
XL    XL
XC 
Figure 2(c).

 2 sin2
1
2 fC
Sending End Current
Figure 2. Uncompensated Transmission Line Parameters During
LLLG Fault at 1 Sec.
Figure 3. A schematic diagram of TCSC device.
224
(1)
(2)
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, Volume 2, Issue 3, March 2012)
The effective reactance (XTCSC ()) of TCSC operates in
three region, inductive region, capacitive region and
resonance region. Inductive region starts increasing from
TCR reactance XL||XC value to infinity and decreasing from
infinity to capacitive reactance XC for capacitive region.
Between the two regions, resonance occurs. [3]
Range of firing angle ()
Figure 4.
Equivalent circuit of TCR
For the variation of  from 0 to 90°, XL () varies from
actual reactance (XL) to infinity. This controlled reactor is
connected across the series capacitor, so that the variable
capacitive reactance, as fig. 3 is possible across the TCSC
which modify the transmission line impedance. Effective
TCSC reactance Xtcsc with respect to alpha () can be given
as (3-7)-
XTCSC ( )   XC  C1(2(   )  sin(2(   )))
 C 2 cos2 (   )( tan( (   ))  tan(   ))
C1 
XC  XLC

90º    Llim
Inductive region
Llim    Clim
Resonance region
Clim    180º
capacitive region




 4 XXLLC 





Region
2
C2
XLC

XC XL
XC  XL 
Figure 6. Resonance condition of TCSC.

XC

XL


IV. RESULTS AND DISCUSSION
Thyristor Controlled Series Capacitors are connected in
series of the transmission line. The TCSC inserted at the
midpoint of the transmission line to enhance controllability
and increase power transfer capacity of transmission line.
The capacitance of TCSC is 306μf and the inductance of
TCSC is 4.4mH. The TCSC is operated in three regions
between the angles 90° to 180°.
Figure 5.
Equivalent circuit of TCSC.
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Website: www.ijetae.com (ISSN 2250-2459, Volume 2, Issue 3, March 2012)
Figure 7.
Model of Compensated Transmission Line Using PSCAD.
A. OPEN LOOP
1) Inductive Region
In this region, The TCSC operated in the bypassed Thyristor
mode. The TCSC normally connected at that region. The
gate pulses are applied as soon the voltage across the
Thyristor reaches zero and become positive. However the
net current through the module is inductive.
Figure 8(a).
Figure 8(b).
Receiving End Voltage
Figure 8(c).
Sending End Current
Real Power
Figure 8. Parameters of Transmission Line in Inductive Region
During LLLG Fault at 1 Sec.
226
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, Volume 2, Issue 3, March 2012)
Faults occur on transmission line when TCSC operated in
inductive region then the TCSC inductor come in to the
picture and the function of TCSC inductor is limit the fault
current. Fig. 7(c) Shows the current wave form it is
indicating that during the fault the short circuit current
limited by the inductor of TCSC.
3) Capacitive Region
In this region, The TCSC is fully conducted. The value of
net capacitive reactance of TCSC is increases and the net
reactance of transmission line further reduces compare to
inductive region. So that the power transfers capacity and
the voltage stability increases in that region.
2) Sub synchronous resonance region
In this region, the alpha varies from 130° to 140°. This
is called the sub synchronous resonance (SSR) region. In
this region the net reactance and capacitance of the TCSC
nearly equals. So it is act as a resistive circuit at that region
the power factor reach nearly to unity.
Figure 9(a).
Figure 9(b).
Figure 10(a).
Real Power
Figure 10(b).
Receiving End Voltage.
Figure 10(c).
Sending End Current.
Real Power
Receiving End Voltage
Figure 10.
Figure 9(c).
Parameters of transmission line in capacitive
region during LLLG fault at 1 sec.
The magnitude Real power of capacitive region
increases compare to the inductive region because the net
reactance of line reduces. Receiving voltage of line
increases nearly to the sending end voltage to improve the
stability of system.
Sending End Current
Figure 9. Parameters of Transmission Line in Resonance Region
During LLLG Fault at 1 Sec.
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B. CLOSE LOOP
In this control scheme three controls are available
current control, voltage control, impedance control. Here
impedance control of close loop scheme used.
Figure 11.
Reactance Control Method of TCSC for Close
Loop Control.
Figure 12(a).
Real Power.
Figure 12(b).
Receiving End Voltage.
Figure 12(c).
Sending End Current.
Figure 12.
Parameters of Transmission Line During LLLG
Fault at 1 Sec for Close Loop Control.
Real power of close loop control increases compare to
the uncompensated line. Also Receiving end voltage
increases up to some extend to maintain sending end voltage
equal to the receiving end voltage. Faults occur during 1 sec
the real power decreases and receiving end voltage reduce
to zero. The current of line increases up to 2-times of the
fundamental current.
The transmission line voltage and current are used
for a measurement of reactance in transmission line. The
reference value of reactance of transmission line is choosing
from the standard. The measure value of reactance compare
against the reference value of reactance to obtain the error
signal. This error signal fed to the pi controller for the
filtering the gain of pi controller is 2 and the time constant
of 0.5sec. This value gives the alpha for firing circuit of
Thyristor gate.
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References
V. COMPARISON ANALYSIS
[1]
Parameter
Un
Comp.
line
Compensated line
Open loop
90°
Alpha
135°
Close
loop
[2]
[3]
180°
[4]
Real power
per
phase(MW)
Receiving
end voltage
per
164
210
178
215
175
220
226
227
229
225
[5]
[6]
phase(kV)
[7]
Sending end
705
590
650
570
680
current per
phase(kA)
Table 1: parameters of transmission line in different condition for
LLLG fault at 1 sec.
The simulation results of uncompensated lines and
compensated lines gives idea about the transmission line
parameters are shown in the table1. Compensated
transmission line system the power transfer capacity
increases compare to the uncompensated transmission lines.
The voltage drop decreases in compensated transmission
lines to give the receiving end voltage nearly same to the
sending end voltage and improve the stability of the system.
VI. CONCLUSION
In this study, the simulation of EHV Transmission line
using TCSC Controller is carried out. By using the TCSC
Controller in transmission line the real power of
transmission line increases that means power transfer
capacity of EHV Transmission line increases. Also the
receiving end voltage increases to match the value nearly to
the sending end voltage that increasing the stability of the
Transmission Network.
229
N .G .Hingorani, Laszlo Gyugyi, "Understanding FACTS", IEEE
Press, 2001, pp 223-238
R. M. Mathur, R. k. Verma, "Thyristor based FACTS controllers for
electrical transmission systems", IEEE Press, 2002, pp 277-288.
S. Meikandasivam, Rajesh Kumar Nema, Shailendra Kumar Jain,
"selection of TCSC parameters: capacitor and inductor", IEEE 2011.
Xiaobo Tan, Luyuan Tong, Zhongdong Yin, Dongxia Zhang,
Zhonghong Wang, "characteristic and firing control of thyristor
controlled series compensation installations", IEEE 1998.
Milad Dowlatshahi, Mehdi Moallem, Hadi Khani, "A new approach
for voltage profile enhancement in distribution power system using
fixed and thyristor controlled series capacitor",IEEE 2010.
Zhao Xueqiang, “study of TCSC model and prospective application
in the power systems of china” IEEE international conference on
power electronics and drive systems, hong kong, july 1999.
J. R. S. S. Kumara, A.M.T.K. Bandara, A. Atputharajah, J. B.
Ekanayake, "design and testing of an TCSC for distribution network
application", ICIIS first international conference on industrial and
information systems, srilanka, august 2006.