The document discusses the enhancement of dynamic stability in multimachine power systems using various Flexible AC Transmission Systems (FACTS) devices. It reviews different FACTS controllers, such as STATCOM, SVC, and TCSC, and analyzes their effectiveness in improving power transmission capacity and stability during faults. The findings indicate that these devices can significantly mitigate power losses and enhance overall system performance.

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International Journal of Electrical Engineering & Technology (IJEET)
Volume 7, Issue 3, May–June, 2016, pp.169–179, Article ID: IJEET_07_03_014
Available online at
http://www.iaeme.com/ijeet/issues.asp?JType=IJEET&VType=7&IType=3
ISSN Print: 0976-6545 and ISSN Online: 0976-6553
Journal Impact Factor (2016): 8.1891 (Calculated by GISI) www.jifactor.com
© IAEME Publication
DYNAMIC STABILITY ENHANCEMENT IN
MULTIMACHINE POWER SYSTEMS BY
DIFFERENT FACTS DEVICE
Muqueem M Khan
PG Student [EPS], Dept. of Electrical, SSBT’s COET
Bambhori, Jalgaon, Maharashtra, India
M M Ansari
Assistant Professor, Dept. of Electrical, SSBT’s COET,
Bambhori, Jalgaon, Maharashtra, India
ABSTRACT
Modern Power system are becoming increasingly stressed due to
increasing demand of electricity and restriction on new transmission network
.This effect of power network is that transmission power loss increases and
decreasing power transmission capability of network. And also stability of
synchronous alternator is lost. There are electronic based FACTS (Flexible
AC Transmission system) devises is established to enhance the power
transmitting capacity. A major important function of FACTS devises is to
enhanced power transmission capacity of power system network without
increasing power generation capacity of power system. Because system
voltage is inversely proportional to transmission loses. Hence system voltage
increases by connecting different FACTS devises in the system then overall
loses of power transmission reduces. Stability enhancement is also important
function of FACTS devises. In this paper we analyses the performance of
different power system stabilizer at the time of fault occur in the power
transmission network, and comprised the performance of different FACTS
controller that which one is best for technical point of view.
Key words: Flexible AC Transmission Systems (FACTS), FACTS
Controllers, STATCOM, SVC, Power Systems, Power System Stability,
Transient Stability, Voltage Stability. SSSC, TCSC
Cite this Article: Muqueem M Khan and M M Ansari, Dynamic Stability
Enhancement In Multimachine Power Systems by Different Facts Device.
International Journal of Electrical Engineering & Technology, 7(3), 2016, pp.
169–179.
http://www.iaeme.com/ijeet/issues.asp?JType=IJEET&VType=7&IType=3

2. Muqueem M Khan and M M Ansari
http://www.iaeme.com/IJEET/index.asp 170 editor@iaeme.com
1. INTRODUCTION
A generating power station in allover world are interconnected to each other due to
obtaining integrity of power of power ie,whenever a fault occur in any one of the line
or any one plant of power station is shutdown so continuous power is to be taken from
another generating power plant. But due to interconnected system electromechanical
oscillation is introduce. Also increasing loading condition and interconnection the
transmission system become weak and inadequate, and load characteristics added to
the problem causing oscillation. These uncontrolled electromechanical oscillation
may responsible to total or partial power interruption [1].
The basic static var compensator (SVC) controls strategies to enhancing the
dynamic and transient stabilities in simple two machine system [3]. The control
aspects of Thyristor Controlled Series Capacitor (TCSC) to schedule line power and
damp system oscillation in a single machine Infinite Bus (SMIB) system was
analyzed in [4]. The model of Static Synchronous Compensator (STASCOM) for
voltage and angle stability studied in [5]. The impact of static synchronous series
compensator (SSSC) control mode on the small signal and transient stability of a
single machine infinite bus was established in [6]. The efficiency of STATCOM and
SSSC controllers in improving the damping power and synchronizing of SMIB was
investigated [7]. The interfacing technique and modeling of TCSC and SVC for a long
term dynamic simulation was studied in [8]. The Phillips heffron model of the
multimachine power system was used for analyzing the small signal stability with
Unified power flow Controller (UPFC) in [9]. Speed deviation signal was used as the
damping controller input. Damping impotent in SMIB system using SSSC and
STATCOM was established using energy function method [10]. The dynamic
behavior of source convertor based FACTS devices for simulation studied was
discussed in [11]. The concept of induced synchronizing and damping torque due to
SVC based stabilizer in a multimachine power system is elaborated in [11,12].
2. CLASSIFICATION OF FACTS DEVICES
Figure 1 Classification of FACTS devices [13]
FACTS
Series compensation Shunt compensation
TCSC STATCOMSSSS SVC
Combined Series-Shunt
Compensator
TCR TSR TSC
UPFC

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STATIC VAR COMPENSATOR (SVC)
A shunt connected static VAR absorber whose output is adjusted to exchange
capacitive or inductive current so as to control specific parameter of electrical power
system.
STATIC SYNCHRONOUS COMPENSATOR (STATCOM)
Static synchronous compensator operated as shunt connected devices whose
capacitive or inductive output current current can be controlled independent of the ac
system voltage.
THYRISTOR CONTROLLED SERIES CAPACITOR (TCSC)
A capacitive reactor compensator which consists of series capacitor bank shunted by a
thyristor controlled reactor in order to provide a smooth variable series capacitive
reactor.
STATIC SERIES SYNCHRONOUS COMPENSATOR (SSSC)
Static Series Synchronous Compensator is operated without an external electric
energy source as a series compensator whose output voltage is an quadrature with and
controllable independently of, the line current for the purpose of increasing or
decreasing the overall reactive voltage drop across the line and controlling the
transmission power. SSSC operation like STATCOM but its output voltage is in
series with the line.
UNIFIED POWER FLOW CONTROLLER (UPFC)
A combination of static synchronous compensator (STATCOM) and Static series
compensator (SSSC) connected via DC link to pass flow of real power between the
series output terminal of SSSC and shunt output terminal of STATCOM.
EQUIVALENT CIRCUIT FOR UPFC
The UPFC is the most versatile FACTS controller with three control variable. The
phase angle and magnitude of series injected voltage in addition with reactive current
drawn by the shunt connected SVC are three control variable. Equivalent circuit
shown in fig.
The shunt current ‘I’ has real (Ip) and reactive (Ir) component. Similarly series
injected voltage ‘V’ has real Vp and reactive Vr component. The positive value of Ir
and Vr
Indicate reactive power drawn by the shunt convertor and supplied by series
convertor. Neglecting lose in UPFC, the constant equation is,
V1 Ip =I2 Vp
The remaining shunt and series connected FACTS controller are special cases of
UPFC. Eg in STATCOM,
Vp= 0, Vr= 0, Ip= 0 and Ir is +ve.
Ina SSSC
Ip= 0, Jr= 0, Vp= 0 and Vr is +ve.
In a SVC,
Vp= 0, Vr= 0, Ip= 0 and Ir = -Vi .Bsvc where Bsvc is the control variable in
a SVC

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Figure 2 Equivalent circuit of UPFC
3. POWER SYSTEM STABILITY
Stability of power system is the ability of system to remain in synchronism when
several faults occur in the system. It may be classified into three categories.
 Rotor Angle Stability
 Voltage Stability
 Frequency Stability
4. SYSTEM MODELLING
A. Two Area System without FACTS Device connected
Figure 3 Two Area System without FACTS Device connected

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Graph 1 Rotor Angle, Power, Terminal Voltage Vs. time
B. Two Area System with SVC connected
Figure 4 Two Area Systems with SVC connected

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Graph 2 Rotor Angle, Power, Terminal Voltage Vs. time
C. Two Area System with STATCOM connected
Figure 5 Two Area Systems with STATCOM connected

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Graph 3 Rotor Angle, Power, Terminal Voltage Vs. time
D. Two Area System with SSSC connected
Figure 6 Two Area Systems with SSSC connected

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Graph 4 Rotor Angle, Power, Terminal Voltage Vs. time
E. Two Area System with TCSC connected
Figure 7 Two Area Systems with TCSC connected

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Graph 5 Rotor Angle, Power, Terminal Voltage Vs. time
F. Two Area System with UPFC connected
Figure 8 Two Area Systems with UPFC connected

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Graph 6 Rotor Angle, Power, Terminal Voltage Vs. time
5. CONCLUSION
The analysis of different FACTS devises is carried out. In this analysis we conclude
that different FACTS devises is beneficial to power system network when a fault
occur in the system. The power electronics controller act quite fast and hence regulate
voltage and power flow during steady sate and dynamic condition. In shunt connected
FACTS controller we conclude that STATCOM give better performance than SVC,
and in series connected FACTS device SSSC give fast performance than other. And
critical clearing time for TCSC is minimum The increasing use of FACTS controller
in future is guaranteed.
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