Smart Grid and Renewable Energy, 2012, 3, 10-16
http://dx.doi.org/10.4236/sgre.2012.31002 Published Online February 2012 (http://www.SciRP.org/journal/sgre)
A New Method for Optimal Placement of TCSC Based on
Sensitivity Analysis for Congestion Management
Abouzar Samimi1, Peyman Naderi2
1Department of Electrical Engineering, Islamic Azad University Boroujerd Branch, Boroujerd, Iran; 2Department of Electrical Engi-
neering, Shahid Rajaee University, Tehran, Iran.
Email: abouzarsamimi@iust.ac.ir, naderi@ee.kntu.ac.ir
Received June 5th, 2011; revised December 7th, 2011; accepted December 14th, 2011
ABSTRACT
In this paper a new method has been proposed to determine optimal location and best setting of Thyristor Controlled
Series Compensator (TCSC). Seeking the best place is performed using the sensitivity analysis and optimum setting of
TCSC is managed using the genetic algorithm. The configuration of a typical TCSC from a steady-state perspective is
the fixed capacitor with a thyristor controlled reactor (TCR). The effect of TCSC on the network can be modeled as a
controllable reactance inserted in the related transmission line. This paper employs the DIgSILENT simulator and the
DPL as a programming tool of the DIgSILENT to show the validity of the proposed method. The effectiveness of sug-
gested approach has been tested on IEEE 14-bus system.
Keywords: TCSC; Optimal Placement; Sensitivity Analysis; Genetic Algorithm
1. Introduction
In recent years, with increasing in development of power
networks, the economical operation of power system is
more considered. Because of deregulation and restruc-
turing of the electricity markets use of Flexible AC Trans-
mission Systems (FACTS) devices is inevitable. The
maximum capability of power systems can be exploited
by means of FACTS devices. Nowadays, development of
power electronics switches causes reduction in the cost
of FACTS and therefore application of FACTS devices
especially in distribution networks is more economical.
Because of the economical considerations, installation
of FACTS controller in all of the buses or the lines is
impossible and unnecessary. There are several methods
for finding optimal locations of FACTS devices in power
systems [1-7].
In [1], a sensitivity based method has been suggested
to optimally locate the Thyristor Controlled Series Com-
pensator (TCSC) and Unified Power Flow Controller
(UPFC) for enhancing the system security under different
operating conditions and at optimal settings of FACTS
parameters. The DC power flow equations have been
employed for calculating the sensitivity indices. In [2], a
genetic algorithm (GA) based method is used to deter-
mine the optimal sitting of FACTS controller in power
system. The fitness function is to minimize the genera-
tion cost. In [3], the genetic algorithm is used to seek the
optimal location of multi-type FACTS devices in a power
system. The optimizations are performed on three pa-
rameters: the location of the devices, their types, and
their values. In [4], the Tabu Search (TS) method is used
to solve the combinatorial (i.e. to determine number and
location) problem of FACTS device allocation. Refer-
ence [5] compares three heuristic methods, simulated
annealing (SA), TS and GA, applied to the optimal loca-
tion of FACTS devices in order to enhance the system
security. The objective function is based on indices quan-
tifying the severity of the contingencies in terms of
branch loading and voltage levels. The three methods
lead to similar results, but generally TS and GA converge
faster than SA to an optimal solution. In [6], a real power
flow performance sensitivity index has been proposed to
decide optimal location of FACTS controllers. In [7],
extended voltage phasors approach (EVPA) is proposed
for placement of FACTS controllers in power systems
within the voltage stability viewpoint.
In this paper a new method has been proposed to op-
timally locate TCSC in power systems. The suggested
approach is composed of sensitivity analysis and the ge-
netic algorithm. Finding the best place for TCSC is per-
formed using the sensitivity analysis and sizing of TCSC
is managed using the genetic algorithm. The IEEE 14-
bus system has been applied to test the suggested algo-
rithm. The rest of the paper is organized as follows. Sec-
tion 2 presents the modeling of the TCSC adapted for this
study. The search space in optimal placement of series
Copyright © 2012 SciRes. SGRE
A New Method for Optimal Placement of TCSC Based on Sensitivity Analysis for Congestion Management 11
capacitive compensators in real power systems is usually
sizable. Use of the approaches like sensitivity analysis
can reduce the search space. In Section 3 some sensitiv-
ity indices have been presented. The best setting of TCSC
is performed by genetic algorithm in Section 4. Finally
numerical results along with some observations and dis-
cussions are presented in Section 4. DIgSILENT soft-
ware which contains a powerful programming language
called DPL1 has been prepared required facilities to exe-
cute the proposed algorithms and corresponding simula-
tions.
2. TCSC Modeling
The IEEE defines the TCSC as a capacitive reactance
compensator which consists of three main components:
capacitor bank C, bypass inductor L and bidirectional
thyristors SCR1 and SCR2. Series capacitive compensa-
tion has been used to increase line power transfer as well
as to enhance system stability. Figure 1 shows the main
circuit of a TCSC.
The firing angles of the thyristors are controlled to ad-
just the TCSC reactance according to the system control
algorithm, normally in response to some system parame-
ter variations. According to the variation of the thyristor
firing angle or conduction angle, this process can be
modeled as a fast switch between corresponding reac-
tance offered to the power system. Assuming that the
total current passing through the TCSC is sinusoidal, the
equivalent reactance at the fundamental frequency can be
represented as a variable reactance XTCSC. The TCSC can
be controlled to work either in the capacitive or the in-
ductive zones avoiding steady state resonance. There
exists a steady-state relationship between the firing angle
αand the reactance XTCSC. This relationship can be de-
scribed by the following equation [8]:
 

Cl
TCSC
lC
XX
X
X
X
(1)
where,

π
π2sin
lL
XX
Figure 4. Loading profile before and after compensation.
Copyright © 2012 SciRes. SGRE
A New Method for Optimal Placement of TCSC Based on Sensitivity Analysis for Congestion Management
16
algorithm. First, the appropriate modeling of the TCSC
has been presented. After introducing some sensitivity
indices, sensitivity analysis approach has been utilized to
find optimal placement of series compensators. In this
process, a real power flow sensitivity index has been
presented. Then the setting of TCSC has been defined by
GA. The objective function has been made of the sever-
ity of the system loading. The result of load flow calcula-
tion before and after compensation process shows reduc-
tion of loading in congested lines.
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Copyright © 2012 SciRes. SGRE