Research Journal of Applied Sciences, Engineering and Technology 4(6): 675-685, 2012
ISSN: 2040-7467
© Maxwell Scientific Organization, 2012
Submitted: December 16, 2012
Accepted: January 08, 2012
Published: March 15, 2012
Statistical Analysis of Shunt-FACTS Devices Impact on Power Flow Control
Mohammad Karimi, Payam Farhadi, Mohammad Bagher Ahmadi,
Tina Sojoudi and Davood Mostafa
Young Researchers Club, Parsabad Moghan Branch, Islamic Azad University,
Parsabad Moghan, Iran
Abstract: In this study, impact of Static VAr Compensator (SVC) on power flow control is studied by
statistical indices. For this purpose, several conventional branches of SVC are introduced and their impacts are
discuses on active and reactive powers flow control on power systems. Peak and least values used as decision
criteria. To compare and discuss the capability of compared SVCs, two statistical indices are used; i.e. Absolute
Percentage Error (APE) and Symmetric Mean Absolute Percentage Error (SMAPE). These indices help to result
in analysis and extract novel aspect of behavior of SVCs. Simulations have been carried out in
MATLAB/SIMULINK environment. In this study, first a general review on lectures about SVC has been done
which has four parts; i.e. design, placement, application and modeling, respectively. Then, the most useful
branch is chosen.
Key words: Power flow control, Shunt-FACTS devices, statistical indices, SVC
INTRODUCTION
Simple structure and many capabilities of SVC has
led to composite new structure with other devices; e.g.
AVR for voltage control (Vachirasricirikul et al., 2010),
PSS for damping multi electromechanical modes in
multimachine systems (Bian et al., 2011), and to increase
power system stability (Abido and Abdel-Magid, 2003).
To damp rotor angle oscillations and improve the
stability, Karpagam et al. (2010) suggested an improved
FLC for SVC. Main contribution of proposed FLC is
oscillations damping with faster rate and optimal
utilization of the SVC in system-overloading conditions.
Sun et al. (2011) have designed a SVC based on H4
controller to damp coefficient uncertainty by modifying
adaptive backstepping sliding mode control method and
Lyapunov methods. Simulations have been done by
MATLAB software on SMIB case system. A novel
approach based on interval systems theory and
Kharitonov’s Theorem was proposes by Robak (2009), to
improve electromechanical oscillations damping using
SVC. Proposed approach resulted in facilitating the
design of a low-order, fixed-parameter and robust
controller. Venayagamoorthy and Sandhya (2008) have
designed a DFN controller based on wide-area
measurements to improve damping characteristics of
power system. The main advantage of the DFN controller
is its simple structure with less development time and
hardware requirements for real-time implementation.
Finding optimal SVC location resuled in better
performance in power system. Benabid et al. (2009) have
used NSPSO to find optimal placement of SVC and
TCSC. The proposed technique was tested on IEEE
(1994) 30-bus and realistic Algerian 114-bus power
The SVC is basically a shunt-connected static VAr
generator/load its output is adjusted by exchange
capacitive or inductive current, so as to maintain or
control specific power system variables; typically, the
controlled variable is the SVC busbar voltage. However,
by growing use of the SVC, the coordination design
problem of multiple SVC controllers in joint operation
should be considered in practical power systems (Zou et
al., 2005).
Many lectures have studied SVC in different aspects.
The lectures are classified in four categories; i.e.
designing applications, optimal placement and analysis.
Changes and improvements have been proposed to
optimal performance of SVC. Then, this part of review
consists of three subparts: structure modification and
composition as well as design controller.
Mahanty (2010) has proposed MSVC for reactive
power compensation to eliminate harmonic without filter.
The modification is done by large value AC capacitor.
The large value AC capacitor has obtained using two
large value DC capacitors and power semiconductor
devices.
Modi et al. (2008) a MISO fuzzy neural network has
been developed to evaluate voltage stability in presence
of SVC. The proposed method has two stages; Kohonen
self-organizing map and combination of different nonlinear membership functions proposed to reduce the input
features and combination of different non-linear
membership functions in first and second stage,
respectively.
Corresponding Author: Mohammad Karimi, Young Researchers Club, Parsabad Moghan Branch, Islamic Azad University,
Parabad Moghan, Iran
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Res. J. Appl. Sci. Eng. Technol., 4(6): 675-685, 2012
system and compared with PSO and NSGA. To enhance
power system voltage stability in presence of SVC, Zhang
et al. (2007) have used normal forms of diffeomorphism.
In this study, to confirm ability of proposed approach,
steady-state voltage stability index and the time domain
simulation used as comparison criteria. In this research,
New England 39-bus power system has used as test case.
Farsangi et al. (2007), proposed first a technique to
find optimal allocation of several SVCs based on their
primary function and then the most proper input signal for
supplementary controller is selected.
Other criterion to seek optimal location of SVC is
reactive power nodal price index. The proposed approach
is tested on two practical Indian systems (Singh et al.,
2007).
The SVC has several capabilities which make it to be
used for different targets; in wind system for voltage
adjustment and as a phase compensator (Lahaçani et al.,
2010; Yuan et al., 2010), voltage control capability
(Li et al., 2009), reactive current control for load power
factor correction (Kodsi et al., 2006), power system
dynamic performance (Rahima et al., 2006).
In several studies, diverse approaches for modeling
and studying SVC have been suggested. Quintela et al.
(2008) have presented three-phase model to analyze
power system in presence of SVC. From the modeling, if
a compensator does not deliver reactive power, its
currents are always of a negative-sequence symmetrical
current set.
By comparing dynamic performance between SC and
SVC, it can be verified that the SVC injects more reactive
power and shows better performance during fault
occurrences caused less voltage drop on its terminals, but
during severe faults, SC performs better (Teleke et al.,
2008). Impact of SVC and STATCOM on performance of
distance relays are: errors in the impedance measurement,
delayed response and incorrect phase selection, affecting
relay response time and the phase selection of relay. To
mitigate effect of SVC and STATCOM, there is three
technique; modifying the logic in the existing channelaided schemes, modifying the input voltage and current at
the relays to compensate for the effect of the current of
the shunt-FACTS and detecting remote end breaker
operation vice versa (Albasri et al., 2007).
By using normal forms theory to analyze nonlinear
interactions among multiple SVCs which leads to a better
understanding of the system nonlinear behavior and can
be employed to locate and design controllers, and can also
be extended to accommodate more complex
multi-machine power system and other FACTS devices
(Zou et al., 2005).
Main focus of this work is comparative study of
several branches of SVC on power flow control. For this,
behavior of several SVCs on active and reactive powers
have been introduced. To compare how these six SVCs
work, control parameters are used and two statistical
indices have been introduced to analyze and discuss.
(a)
(b)
Fig. 1: Basic SVCs: (a) TCR, (b) TSC
Static VAr compensator (SVC): Reactors and capacitors
controlled by thyristor, i.e., static VAr compensator, are
one of FACTS devices. Primary purpose of using SVC is
usually for rapid control of points with week voltage in
network. This device has been used in transmission
systems in order to improve the performance of the
electric power system by providing voltage support;
improving the power factor, transient stability and power
system damping, reduce temporary over-voltages and
control the reactive power flow (Zhou, 1993).
One of the interesting issues about SVC is its
diversity in structure which is outmost over the most
common SVC explains.
TCR: The basic element in this type is a reactor in series
with an AC thyristor switch, shown in Fig. 1a. The fixed
capacitor biases the reactive output of the compensator
into the generating regime. The demand for reactive
power is met by controlling the duration of the conducting
interval in each half-period by gating pulses to the two
oppositely poled thyristors (Montafio et al., 1993).
TSC: In their simplest configuration, the TSCs are
constituted by a capacitor bank where each capacitor may
be connected to the system through a thyristor switch
(Fig. 1b). Very often all the capacitors in the bank have
the same size but, by suitably choosing different values
for each capacitor, 2n different compensation levels could
be provided. In the standard construction of a TSC a
damping reactor is included to limit the rate of change of
device current on switching and to dampen transients
following the switching (Celli et al., 2000).
TSC-TCR: In AC power distribution systems TSC-TCR
are increasingly used in order to support the voltage, and
improve the transient stability. In such a system, the
number of switched "ON" capacitor banks is selected in
order to generate reactive power in excess, while the
reactors are controlled in order to absorb the difference
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Res. J. Appl. Sci. Eng. Technol., 4(6): 675-685, 2012
Fig. 2: Structure of SVC with FC
Fig. 3: SVC model using power flow PV bus
between the reactive power generated by the capacitors
and the reactive power must be injected in the mains
(Thomas et al., 1994).
In the active control range, current/susceptance and
reactive power is varied to regulate voltage according to
a slope characteristic. The slope value depends on the
desired voltage regulation, the desired sharing of reactive
power production between various sources, and other
needs of the system. The slope is typically 14%. At the
capacitive limit, the SVC becomes a shunt capacitor. At
the inductive limit, the SVC becomes a shunt reactor (the
current or reactive power may also be limited).
With a conventional power flow program, the slope
is represented by connecting the SVC to an auxiliary or
phantom bus separated from the SVC high voltage bus by
a reactance equal (on the SVC base) to the per unit slope.
The auxiliary bus is then the PV bus. Figure 3 shows the
concepts of modeling SVC slope using an auxiliary bus.
The reactive power output of an SVC can be computed as:
SVC with FC: By using TCR and TSC only capacitive or
inductive compensation is possible, but in practice both
types of compensation necessary. Therefore, for
possibility to change inductive form to capacitive, fixed
capacitor is connected to SVC structure (Fig. 2).
C
C
C
FC-TCR: FC-TCR type of static compensator is
analyzed in detail. In this analysis a simplified circuit
as well as an exact circuit of an FC-TCR is
considered. The performances of the simplified and
exact circuits are compared and the results are
verified experimentally.
FC-TSC-TCR: This SVC is composed of three
branches; one, (i.e., TSC) is used to generate variable
reactive power, and another, namely TCR, is for
variable reactive power absorption and FC for fixed
reactive power generation.
FC-TSR-TCR: The FC-TSR-TCR system is
modified by introducing TCRs. The TSR gives
stepped variation in current and TCR gives smooth
variation in current. Thus the range of control of
reactive power can be increased by using TSR. The
TSR system consists of three reactors and three
IGBTs. Three different amplitudes of currents can be
obtained by using three switches. The FC-TSR-TCR
system is best suitable for dynamic loads
(Vijayakumar et al., 2010).
QSVC = Vt (Vt ! Vref) Xsl
(1)
Equation (1) is valid as long as the reactive power
output of the SVC, QSVC is within limits set by Qind and
Qcap; defined as (Preedavichit and Srivastava, 1998):
Qind = BindV2ref
(2)
Qcap = BcapV2ref
(3)
Power analyze and basic structure of SVC and
analyze the survey of such systems mathematically in
(Quintela et al., 2008; Hammad, 1986) can be found,
respectively. The model is completed by the algebraic
equation expressing the reactive power injected at the
SVC node; Fig. 4 (Zou et al., 2005):
Modeling of SVC: The SVCs are often modeled as a
conventional PV (generator) bus with reactive power
limits. This results in large errors if the SVC is on limit,
operating as a capacitor or reactor.
If low voltage is the main concern, the SVC can be
modeled as a FC-TCR type of SVC (PV bus with shunt
capacitor). For example, for low voltage problems, a ±200
MVAr SVC can be represented as a 200 MVAr capacitor
banks, and a PV bus with 400 MVAr inductive limits and
zero capacitive limits; the capacitive limit is correctly
represented but not the inductive limit.
With a conventional power flow program, a SVC
with susceptance regulator can be represented by a PQ
(load) bus with voltage constraints.
CALCULATING FIRING ANGELES
OF THYRISTOR
There are, mainly, three existing SVC models in load
flow calculations, e.g., the generator-fixed susceptance
model, the total susceptance model and the firing angle
model. Calculating firing angle could be carried out in
time or frequency domains. Assuming sinusoidal voltage
source, calculating firing angle will be done with less
complications. To calculate firing angles of TCR’s
thyristors, equivalent circuit shown in Fig. 1 is
transformed to the circuit shown in Fig. 5.
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Res. J. Appl. Sci. Eng. Technol., 4(6): 675-685, 2012
Bmax
VSV Cref +
K SV C
1  sT SV C
BSVC
Bmin
VSVC
Fig. 4: Control model SVC
ix ( t)
i (t)
v (t )
iL (  , t )
ic ( t )
L oa d
C
Fig. 5: FC-TCR equivalent circuit
According to the figure, it is not obliged load to be
linear and it is viable that analyze the non-linear load. All
elements and branches current are depicted in the figure
and it obviates description. It should be mentioned that if
we assume that reactor L in Fig. 5 is variable then FCTSR-TCR configuration will be obtained. Therefore,
circuit analysis will be similar for both FC-TCR and FCTSR-TCR modes.
Firing angle " should be calculated such that drawn
current from voltage source has to be declined to its
minimum amount, and power factor correction is also
reached. Suppose voltage and current density equations
will be as follows (Gutierrez et al., 2002):
v(t) = Vcos Tt
J1 

T
i 2 (t ) dt
Minimizing J1 is reached when:

0

(5)
T
0
(i L  ix )
i L
dt  0

(8)
( 2   ) / 

V cos  (   )
(i L  i x ) dt 
(i L  ix )dt   0

L   / 
(   ) / 



4V  

 (   ) sin   cos   A(ix , )
L 2  2

From the Fig. 5, applying Kirchhof’s current law in
TCR’s node we have:
V
(sin t  sin  )   t    

 L
iL ( , t )  
 V (sin t  sin  )     t  2  

 L

(9)
For " … B / 2, below equation should be zero. Substituting
Eq. (7) in the above equation leads in:
0
i(t) = ix (t) + iL (" , t)
i 2 ( t )
dt  2

Substituting il /  &il / &" in Eq. (5), we get:
(4)
T  2 / 
T
(10)
where A(ix, ") is as follows:
(6)
A (ix , )  
(   ) / w
/w
(7)
ix dt 
( 2   ) / w

(  ) / w
ix dt
(11)
Figure 5 shows function A(ix, ") and the amount of "
satisfying in Eq. (10) expresses. It should be considered
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Res. J. Appl. Sci. Eng. Technol., 4(6): 675-685, 2012
Fig. 6: Simulated circuit
(12)
SIMULATION RESULTS
250
200
150
100
50
00
-50
-100
-150
-200
-250
1.15
1.20
1.25
Time (s)
In this section, six SVCs are tested on test case
system. For simulations, FC-TSR-TCR circuit is
considered with variable inductance L=0.1KL/T where
KL=1, 2, 3, …, KLmax and fixed capacitor C=0.4/T. Also,
load impedance is z = kz(1+2j)(–) where Kz=1,2,3,4.
(Fig. 6).
Considering circuit frequency equal to 50Hz, T =
100B, KL = 300, kz = 20, and " = 60o simulation results
are obtained as follows Fig. 7 shows magnitude of current
source. In Fig. 8 and 9, switching pulses for each
thyristors and reactor taps voltage have been illustrated,
respectively. Four switching pulses for parallel switches
in Fig. 10 has been depicted. Finally, current and voltage
outputs in Fig. 11 and 12 have been showed, respectively.
Fig. 7: Current source
2.0
1.5
1.0
S
F 0.5
0
-0.5
0.10
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0
0.01
-1.0
Time (s)
(a)
Active power: First, we will discuss about how behavior
these six branches of SVC on active power. Figure 13
shows active power in presence SVCs. It should be noted
that shunt reactors applications in FC-TCR-TSC and
FC-TSR-TCR circuits are entered using signals which are
sent to the shunt switches. In the simulations, these
reactors are switched out in 1.4 sec.
Generally, in presence capacitor, range of active
power is limited; this concept is clear in comparison
Fig. 13a with b and TSC with TCR. Range variation
TCR-TSC is average of Range variation of TCR and TSC,
approximately; presence FC doesn't change this fact.
Values of peak value, least value and fall time have been
2.0
1.5
S
T2
1.0
0.5
0
-0.5
Time (s)
(b)
Fig. 8: Switching pulses for thyristors 1 and 2
679
0.10
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0
0.01
-1.0
0.02
4V  

(   ) sin   (1 LC 2 ) cos   A(ix , )
L2  2

Source current
that " = B/2 is a solution for Eq. (10). If iz is measured
instead of ix, optimal amount of " will be obtained using
following equation:
Res. J. Appl. Sci. Eng. Technol., 4(6): 675-685, 2012
(a)
(b)
(c)
(d)
Fig. 9: Reactor taps voltage
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Res. J. Appl. Sci. Eng. Technol., 4(6): 675-685, 2012
15
15
10
S
Tap 1
Output current
10
5
0
5
0
-5
0.20
0.46
0.44
0.42
0.40
0.38
0.36
0.34
0.30
0.26
Time (s)
0.32
-15
0.28
0.18
0.16
0.14
0.12
0.10
0.8
0.6
0.4
0.2
-10
0
Time (s)
(a)
Fig. 11: Output current
500
400
300
200
100
(b)
0.46
0.44
0.42
0.40
0.38
0.34
0.26
Time (s)
-200
-300
-400
-500
0.36
0.20
0.18
0.16
0.14
0.12
0.10
0.8
0.6
0
0.4
0.2
0
00
-100
0.32
5
0.30
Output voltage
S
Tap 2
10
0.28
15
Time (s)
15
Fig. 12: Output voltage
10
S
Tap 3
1600
TSC
1400
1200
Active power
5
1000
0.20
0.18
0.16
0.14
0.12
0.10
0.8
0.4
0.2
0
0.6
0
800
TCR
600
TCR-TCS
400
Time (s)
200
1.6
1.8
2.0
1.8
2.0
1.4
1.2
1.0
1.6
15
0.8
0.6
0.4
0
0.2
0
(c)
Time (s)
(a)
S
Tap 4
10
1500
FC-TCR-TSR
FC-TSR-TCR
Active power
5
1000
0.20
0.18
0.16
0.14
0.12
0.10
0.8
0.6
0.4
0
0.2
0
FC-TCR
500
Time (s)
(d)
Fig. 10: Switching pulses for parallel switches
1.4
1.2
1.0
0.8
0.6
0.4
0
0.2
0
Time (s)
listed in Table 1. TSC has maximum reduction after 1.4
sec; this behavior by installing FC is eliminated. Between
first transient state to 1.4 sec, variation slope of SVCs is
constant except TCR-TSC and FC- TCR-TSC.
(b)
Fig. 13: Comparison between active power (a) without
capacitor and (b) with capacitor
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Res. J. Appl. Sci. Eng. Technol., 4(6): 675-685, 2012
(a)
(b)
Fig. 14: Comparison between reactive power (a) without capacitor and (b) with capacitor
Table 1: Values of control parameters of active power
Value
TSC
TCR-TSC
FC-TCR-TSC FC-TSR-TCR
Peak
1121
1127
948
1000
Least
869
865
842
842
Table 2: Values of control parameters of active power
Value
TSC
TCR-TSC
FC-TCR-TSC
FC-TSR-TCR
Peak
2211
2155
1952
1975
Least
1607
1703
1677
1677
In Table 1, values of control parameters of TCR and
FC-TCR haven't been presented; because these values are
constant and are selected as base value for comparison.
Magnitude of active power in presence TCR and
FC -TCR are 922 and 851 kW, respectively. By
considering results of Table 1, maximum and
minimumpeak value in between SVCs devote for TSC
and FC-TCR-TSC. TCR-TSC has maximum peak value.
Least value of FC-TCR-TSC and FC-TSR-TCR are equal
and these values are minimum least value.
Table 2, maximum peak and least value are values of TSC
and TCR-TSC, respectively. FC-TCR-TSC has minimum
peak value. The least value of FC-TCR-TSC and
FC-TSR-TCR, respectively is equal and this value is
minimum least value.
COMPARISON AND DISCUSSION
To confirm capability of each one of SVCs, three
statistical indexes are introduced. these indexes are APE
and SMAPE as well as SSE.
Values of peak and least of SVCs are compared with
values of TCR. The behavior of TCR and FC-TCR in
duration simulation are constant thus are proper base to
comparison, also TCR has simple structure respect to
FC-TCR.
Reactive power: In this section, impact of SVCs on
reactive power is analyzed. Figure 14 illustrates reactive
power in presence SVCs.
Due to Fig. 14, generally behavior each SVCs is
similar with active power case. Range variation of
reactive power in two times range variation of active
power, approximately. TCR-TSC, and FC-TCR-TSC,
respectively as well as TCR have warped to up 1.4 sec.
In Table 2 values of peak and least of SVCs have
been listed.
Values of steady stat of TCR and FC-TCR are 1703
and 1800 kVAr, respectively. By attending to results of
APE: APE used as comparison criteria, this parameters is
defined following as:
APE % 
682
f
TCR
f
 f
TCR
other
 100
(13)
Res. J. Appl. Sci. Eng. Technol., 4(6): 675-685, 2012
11.76
2.77
2.77
0.77
1.39
FC-TCR
FC-TSR-TCR
FC-TCR-TSC
0
0.77
4.53
4.0
4.53
6.81
7.39
10
3.2
power, this fact in FC-TCR-TSC and FC-TSR-TCR is
considerable, respectively. The SMARE of reactive power
least of TSC-TCR and FC-TCR-TSC as well as
FC-TSR-TCR, respectively. Figure 16 shows values of
Table 4 as schematic.
CONCLUSION
In this study, two statistical indices are introduced to
compare and discus haw impact of six branches of SVC
on active and reactive power control. These indices are
Absolute Percentage Error (APE) and Symmetric Mean
Absolute percentage Error (SMAPE) and SVCs consist of
Thyristor Switched Capacitor (TSC), Thyristor Controlled
Reactor (TCR), Fixed Capacitor Thyristor Switched
Reactor Thyristor Controlled Reactor (FC-TSR-TCR),
fixed capacitor Thyristor Controlled Reactor ThyristorSwitched Capacitor, (FC-TCR-TSC), Fixed Capacitor
Thyristor Controlled Reactor (FC-TCR) and ThyristorSwitched Capacitor and Thyristor- Controlled Reactor
(TSC-TCR) , respectively. From results of Table 1-4,
Reactive power has higher swap respect to active power.
Variation range of reactive power is more than active
power. In all cases, behavior of TCR and FC-TCR,
respectively is constant after transient state. Presence of
Fixed Capacitor (FC) is led to decrement of peak and least
values; then by installing FC on SVC s reduce variation
SMARE: SMARE is proper index to show magnitude
difference. In this index, difference of two parameters is
divided by sum of these parameters. In fact the SMARE
normalizes absolute percentage error,
 100
TCR-TSC
TSC
FC-TCR
Table 4: Obtained SMARE from comparison between TCR and other
SVCs
Value
TSC
TCR FC-TCR FC-TSR
FC-TCR
-TSC -TSC
-TCR
Active
Peak 9.74
10.00 1.39
4.06
4.00
Least 2.96
3.20
4.53
4.53
Reactive Peak 12.98
11.76 6.81
7.39
2.77
Least 2.90
0.00
0.77
0.77
where, |f|TCR and |f|other are peak and least values of TCR
and other SVCs, respectively. Values of APE have been
presented in Table 3.
By considering results of Table 3, APE of peak
values of reactive power is more than active power while
this fact in least values was vice versa. The presence of
FC has reduced APE in all cases, this reduction in active
power is several times respect to reactive power.
Maximum APEs of active and reactive power are
TCR-TSC and TSC, respectively. The Table has been
illustrated as schematic in Fig. 15.
f TCR  f other
44
Fig. 16: Obtained SMARE from comparison between TCR
and other SVCs
Table 3: Obtained APE from comparison between TCR and other SVCs
TSC
TCR
FC-TCR
Value
-TSC -TSC
-TCR
FC-TSR FC-TCR
Active
Peak -21.58 -22.25
-2.82
-8.46
7.70
Least 5.75
6.18
8.68
8.68
Reactive Peak -29.83 -26.54
-14.62
-15.97 -5.70
Least 5.64
0
1.53
1.53
f TCR  f other
12.98
2
Fig. 15: Obtained APE from comparison between TCR and
other SVCs
SMARE 
2.9
-8.46
-5.75
-5.75
4
-14.62
-14.62
8
6
0
FC-TCR-TSC
-22.23
-26.54
TCR-TSC
TSC
-30
-21.58
-25
-29.83
-15
-20
FC-TSR-TCR
-10
9.74
10
-2.82
0
-5
12
2.96
0
1.53
5
14
7.7
7.7
8.68
8.68
1.53
6.18
5.64
5.75
10
Reactive-Peak
Reactive-Least
Active-Peak
Active-Least
Reactive-Peak
Reactive-Least
Active-Peak
Active-Least
(14)
SMAREs of TCR and other SVCs have been presented in
Table 4.
Due to results of Table 4, peak value of TSC on
reactive power and least value of TCR-TSC on reactive
power have maximum and minimum SMARE,
respectively. Then variation range of SMARE of reactive
power is more than active power. In all case, SMARE of
active power peak is more than related value of reactive
683
Res. J. Appl. Sci. Eng. Technol., 4(6): 675-685, 2012
range. In all cases, slope TSC-TCR curve is not zero and
presence of FC does not change this fact.
In summary, from the viewpoint of power flow
control range, these six kinds of SVC can be classified as
follows (from lowest to highest range), FC-TCR, TCR,
FC-TCR-TSC, FC-TSR-TCR, TCR-TSC and the TSC,
respectively.
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NOMENCLATURE
SVC
TCR
TSR
FC
MSVC
SC
FLC
PSS
APE
RSMD
MISO
DFN
KSVC
TSVC
Xsl
Vt
Vref
Bind
Bcap
FACTS
STATCOM
SMIB
AVR
PSHNN
EMTP
SMAPE
PSO
NSPSO
NSGA
TCSC
Static VAr Compensator
Thyristor Controled Reactor
Thyristor Switched Reactor
Fixed Capacitor
Modified SVC
Synchronous Condenser
Fuzzy logic controller
Power System Stabilizer
Absolute percentage Error
Root-Mean-Square Error
Multi Input Signal Output
Dual-Function Neuron
Gain constant of SVC
Time constant of SVC
Equivalent slope reactance
Node voltage magnitude
Reference voltage magnitude
Inductive susceptance
Capacitive susceptance
Flexible AC Transmission System
Static Synchronous Compensator
Single-Machine Infinite-Bus
Automatic Voltage Regulator
Self-Organizing Hierarchical Neural
Network
Traditional Electromagnetic Transients
Program
Symmetric Mean Absolute Percentage Error
Particle Swarm Optimization
Non-dominated Sorting PSO
Non-dominated Sorting Genetic Algorithms
Thyristor Controlled Series Capacitor
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