International Journal of Research (IJR) Vol-1, Issue-8, September2014 ISSN 2348-6848
Implementation of TCSC on a Transmission Line Model to
analyse the variation in Power Transfer Capability
Prof.Sushil Kumar
Electrical and Electronics Deptt
Pragati college of Engg and Management Raipur
Email sk1_bit@rediffmail.com
observed with the inclusion of TCSC in
Abstract—
the model.
The FACTS controllers clearly enhance
power system performance, improve
Keywords:
quality of supply and also provide an
FACTS, TCSC, power quality, firing
optimal
angle
utilization
of
the
existing
resources. This paper discusses the
development of a Thyristor Controlled
1. Introduction:
Series Capacitor (TCSC) with open loop
Facts Definition:
control system. The TCSC circuit and
A Flexible Alternating Current
characteristics are discussed in brief.
Transmission System (FACTS) is a
Next
system comprised of static equipment
the
determination
of
TCSC
parameters is discussed. With these
used
parameters the capacitive mode of
electrical energy. It is meant to enhance
operation of TCSC is simulated and
controllability
implemented on a power system model
transfer capability of the network. It is
with 300 km long transmission line.
generally a power electronics -based
MATLAB R2006b software had been
device.
used as the simulation tool. Results of
for
the AC transmission
and
increase
of
power
FACTS is defined by the IEEE as
discussed.
"a power electronic based system and
Significant enhancement in the power
other static equipment that provide
transfer capability of transmission line is
control of one or more AC transmission
simulation
P a g e | 1091
made
are
IMPLEMENTATION OF TCSC ON A TRANSMISSION LINE MODEL TO ANALYSE
THE VARIATION IN POWER TRANSFER CAPABILITY | Prof. Sushil Kumar
International Journal of Research (IJR) Vol-1, Issue-8, September2014 ISSN 2348-6848
system
parameters
controllability
and
to
enhance
increase
power
Fig. – 1
Series Compensation
transfer capability."
TCSC:
P=
Thyristor
Controlled
Series
E1 ⋅ E 2 sin δ
X
Capacitor (TCSC) is a Flexible AC
…………..(1)
Transmission Systems (FACTS) device.
V = f ( P, Q )
It has proven to be an excellent solution
in controlling the power flow, especially
…………(2)
over long transmission lines where the
Here, in fig.1, E1 and E2 denote
power angle control at either end of the
line are constrained. The TCSC can also
the voltages at either end of the
be used for damping power oscillations
interconnection, whereas δ
and
angular difference of the voltages
mitigating
subsynchronous
denotes the
(E1&E2). X is the reactance of the
resonance.
transmission circuit, while P and Q
2. Fundamentals:
denote the active and reactive power
Series compensation has been
flow.
utilized for many years with excellent
From (1) it is evident that the
results in AC power transmission in a
flow of active power can be increased by
number of countries all over the world.
decreasing the effective series reactance
The usefulness of the concept can be
of the line. Similarly it is demonstrated
demonstrated
that
by
well-known
by
introducing
a
capacitive
expressions relating to active power
reactance in the denominator of (1), it is
transfer and voltages.
possible to achieve a decrease of the
angular
separation
with
power
transmission capability unaffected, i.e.
an increase of the angular stability of the
link.
FACTS devices are used for the
dynamic control of voltage, impedance
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IMPLEMENTATION OF TCSC ON A TRANSMISSION LINE MODEL TO ANALYSE
THE VARIATION IN POWER TRANSFER CAPABILITY | Prof. Sushil Kumar
International Journal of Research (IJR) Vol-1, Issue-8, September2014 ISSN 2348-6848
and phase angle of high voltage AC
The degree of TCSC basic
transmission lines. Different FACTS
compensation
devices in the power system are Static
capacity size of capacitor C. The main
Var Compensators (SVC’s), Thyristor
function of bypass inductance L is to
controlled series compensators (TCSCs),
reduce the short circuit current and the
STATCOMs,
energy absorbed by MOV.
Unified
Power
Flow
Controller (UPFC).
is controlled
by the
Bidirectional thyristor SCR is
In this work, only TCSCs had
used
to
transform
the
equivalent
been used for simulation, study and
impedance of TCSC which fulfill the
analysis.
needs in all kinds of power system
condition,
such
as
improving
the
stability, increasing the transmission
capability,
restraining
hyposynchronization resonance and so
on.
3. Basic Structure of TCSC:
By controlling the trigger pulse,
The basic structure of TCSC is
shown in Fig.2. It is mainly constituted
by four parts: series compensating
capacitor
C, bypass
inductance
L,
bidirectional thyristor SCR and zinc
oxide voltage limiter MOV.
TCSC can transform the trigger angle of
thyristor. Subsequently, the current value
of
inductance
subcircuit
which
controlled by TCSC can be transformed,
and then the total equivalent impedance
will be changed continuously.
Generally, when the trigger angle
is 145
O
~180
o
, the equivalent
impedance of TCSC is appeared as
capacitance. When the trigger angle is
90o ~140o , the equivalent impedance of
TCSC is appeared as inductance as
which characteristic can restrict short
Fig. 2 TCSC Module
circuit current during system failure. A
circuit breaker is also installed across the
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IMPLEMENTATION OF TCSC ON A TRANSMISSION LINE MODEL TO ANALYSE
THE VARIATION IN POWER TRANSFER CAPABILITY | Prof. Sushil Kumar
International Journal of Research (IJR) Vol-1, Issue-8, September2014 ISSN 2348-6848
TCSC module to bypass it if a severe
4. Effective reactance of TCSC:
fault or equipment malfunction occurs.
The effective reactance of TCSC
A current limiting inductor, Ld, is
is given by equations (3) and (4).
incorporated in the circuit to restrict both
Equation (3) assumes that the capacitor
the magnitude and the frequency of the
voltage is free from harmonics and
capacitor current during the capacitor
considers the only the TCR current
bypass operation.
harmonics.
 ( X 1TCR ⋅ X C ) 

X 1TCSC = 

 j ⋅ ( X 1TCR ⋅ X C ) 


2 σ
 2 λ2  2 ⋅ cos 2
= − j ⋅ X C 1 + ⋅ 2
 2
 π λ −1  λ −1


X 2 TCSC
……..(3)




(
)
σ
σ
σ
σ
sin


   
⋅  λ ⋅ tan  λ  − tan   −   −

2 
 2
 2   2 


……….(4)
where ,


π
X 1TCR = j ⋅ ω ⋅ L ⋅ 

σ − sin (σ ) 
λ=
ω0
ωN
ω0 =
………(5)
…….(6)
1
…….(7)
L⋅C
In the above equations, σ is the
conduction angle, L is the inductance of
the TCR inductor, C is the capacitance
of the fixed capacitor, ωN is power
system frequency in radians per second
and ω0 is the resonant frequency of the
TCSC circuit. Fig. 3 shows the reactance
characteristics of TCSC.
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IMPLEMENTATION OF TCSC ON A TRANSMISSION LINE MODEL TO ANALYSE
THE VARIATION IN POWER TRANSFER CAPABILITY | Prof. Sushil Kumar
International Journal of Research (IJR) Vol-1, Issue-8, September2014 ISSN 2348-6848
Fig.-3. Reactance Characteristics of
The nominal compensation is
75%, i.e. using only the capacitors
TCSC
(firing angle of 90deg). The natural
5. Simulation of
transmission Line with TCSC:
oscillatory frequency of the TCSC is
150.6 Hz, which is 2.51 times the
fundamental frequency
5.1 Description of the system
From the simulated model, system
performance characteristics had been
model:
A 735 kV, 300 km line is used to
analysed without a TCSC and with a
transmit power from bus B1 (735 kV
TCSC is connected at mid point of the
equivalent system) to bus B2 where RL
transmission line.
load (P=1000MW and Q= 10e3 var) is
5.2 The simulated model:
connected. In order to simplify, only one
It is shown in fig. 4 below.
phase
of
the
system
has
been
represented.
Fig.-4. Simulation of TCSC (on transmission system)
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IMPLEMENTATION OF TCSC ON A TRANSMISSION LINE MODEL TO ANALYSE
THE VARIATION IN POWER TRANSFER CAPABILITY | Prof. Sushil Kumar
International Journal of Research (IJR) Vol-1, Issue-8, September2014 ISSN 2348-6848
5.3 System Parameters:
Transmission Line Inductive Reactance ( X L ) = 98 Ω
TCSC Parameters:
Capacitor (C)
= 36 µF
Capacitive Reactance
(X C )
= 73.5 Ω
Inductor (L)
= 31 mH
Inductive Reactance
(X L )
= 11.76Ω
Resonance Factor (λ) = 2.5
Natural Oscillation Frequency of (TCSC): ωo = 946 rad/sec.;
XL
= 0.1 6
XC
f = 150.6 Hz
To observe the power transfer
Started the simulation and observed the
capability of transmission line after
waveforms. At 75% compensation and
using series compensation technique
firing angle, α =146o power transfer is
i.e.TCSC in capacitive mode, it was
1540MW. Observed the corresponding
necessary to keep delay angle (firing
TCSC
angle, α) of thyristors between 1450 to
(Ic),VB1 (Voltage at B1),VB2(Voltage
1800 . With different values of α, the
at B2), TCR current and line current on
simulations were made. Results with α =
five scopes.
146o has been discussed below.
Waveforms are shown in figure -5 (a),
Simulation with firing angle, α =
(b), (c), (d) and (e)
146o
Voltage,
Capacitor
current
:
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IMPLEMENTATION OF TCSC ON A TRANSMISSION LINE MODEL TO ANALYSE
THE VARIATION IN POWER TRANSFER CAPABILITY | Prof. Sushil Kumar
International Journal of Research (IJR) Vol-1, Issue-8, September2014 ISSN 2348-6848
Fig.-5. (a) Active, reactive Power at α=146o (b) Vc, Itcr & voltage at B2 at α=146o
(C) Line current (IL) at B2)
(d) Capacitor current(Ic)
(e) Waveforms of Iak1, Vak1 , Iline ,Iak2 & Vak2
In the model considered (Fig.4),
TCSC is operated in capacitive mode
keeping firing angle(delay angle) α =
1460 the corresponding Active/Reactive
power ,capacitor voltage , capacitor
current ,TCR current and current at node
B2 are given below.
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Active power (P)
1540 MW
Reactive Power(Q)
150 MVAR
Capacitor voltage (V)
650 KV
Capacitor current(Ic)
18 KV
TCR current
10 KA
=
=
=
=
=
IMPLEMENTATION OF TCSC ON A TRANSMISSION LINE MODEL TO ANALYSE
THE VARIATION IN POWER TRANSFER CAPABILITY | Prof. Sushil Kumar
International Journal of Research (IJR) Vol-1, Issue-8, September2014 ISSN 2348-6848
Line current (B2)
=
6
[4]
Design of TCSC for Classroom and
KA
Research Applications on an Analog
6. Conclusion:
Model Power System Vinod K.
Yedidi, Student Member IEEE, Brian
It is observed that with the inclusion
of
TCSC,
power
transfer
increased to 1540 MW. The same power
was
only
685
compensation.
MW
In
K Johnson, Member IEEE. 2006
capacity
without
simulations,
any
with
[5]
Power Grid Corporation India Limited,
Raipur.
[6]
Klaus Habur is Sr. Area Marketing
Manager,
Reactive
Power
different firing angles, power level had
Compensation, Power Transmission
been varied and the corresponding
and Distribution Group (EV) of
change in reactive power is also
Siemens AG in Erlanger, Germany.
observed.
Donal O’Leary, Sr. Power Engineer of
the World Bank is on assignment with
7. References:
the Siemens Power Generation Group
[1] Narain G. Hingorani, Laszlo Gyugyi,
(KWU) in Erlanger.
and Understanding FACTS: Concepts
and
Technology of FACTS,
Wiley-IEEE Press, and December
1999.
[2] Google search (FACTS Theory) from
Wikipedia,
the
(Wiley-
free
encyclopedia
IEEE Press, December
1999 and Modelling and Control,
Springer, March 2006
[3]
Thyristor-Controlled
Series
Compensation: A state of the art
approach for
optimization of
transmission over power links R.
Grünbaum
Jacques
Pernot,
ABB
Power Systems.
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IMPLEMENTATION OF TCSC ON A TRANSMISSION LINE MODEL TO ANALYSE
THE VARIATION IN POWER TRANSFER CAPABILITY | Prof. Sushil Kumar