APPLICATION OF STATCOM to IMPROVED DYNAMIC PERFORMANCE OF POWER SYSTEM

IJSRD - International Journal for Scientific Research & Development| Vol. 2, Issue 09, 2014 | ISSN (online): 2321-0613
All rights reserved by www.ijsrd.com 563
Application of STATCOM to Improved Dynamic Performance of Power
System
S. I. Mavani1 Dr. G. R. Kulakrni2
1
P.G. Student 2
Principal
1
Gujarat Technological University, Ahmedabad, Gujarat, India 2
Kalol Institute of Technology &
Research Center, kalol, Gujarat, India
Abstract— Application of FACTS controller called Static
Synchronous Compensator STATCOM to improve the
performance of power grid with Wind Farms is investigated
.The essential feature of the STATCOM is that it has the
ability to absorb or inject fastly the reactive power with
power grid . Therefore the voltage regulation of the power
grid with STATCOM FACTS device is achieved. Moreover
restoring the stability of the power system having wind farm
after occurring severe disturbance such as faults or wind
farm mechanical power variation is obtained with
STATCOM controller . The dynamic model of the power
system having wind farm controlled by proposed
STATCOM is developed . To validate the powerful of the
STATCOM FACTS controller, the studied power system is
simulated and subjected to different severe disturbances.
The results prove the effectiveness of the proposed
STATCOM controller in terms of fast damping the power
system oscillations and restoring the power system stability.
Key words: STATCOM, Wind Generation, Transient
Stability, Low Voltage Ride through, Wind Turbine Model,
Reactive power, STATCOM
I. INTRODUCTION
Modern power system networks consist of various types of
generators, and loads interconnected to significantly
complex and large transmission and distribution systems
.The size of wind turbines and wind farms are increasing
quickly; a large amount of wind power is integrated into the
power system. To assist the power system in serving the
peak load, the wind turbines for example, can be used as
small power generators that are connected to the distribution
system or directly at the customer’s site. Since the primary
fuel of wind turbines is air, which is free, they are
considered cheap and clean energy resources.
As a consequence, it will become necessary to
require wind farms to maintain continuous operation during
grid disturbances and thereby support the network voltage
and frequency. In addition, in the area of a deregulated
electricity industry, the policy of open access to
transmission systems, which helped create competitive
electricity markets, led to a huge increase in energy
transactions over the grid and possible congestion in
transmission systems. The expansion of power transfer
capability of transmission systems has been a major problem
over the past two decades. Under these conditions, the
modern power system has had to confront some major
operating problems, such as voltage regulation, power flow
control, transient stability, and damping of power
oscillations, etc. FACTS devices can be a solution to these
problems [7].
They are able to provide rapid active and reactive
power compensations to power systems, and therefore can
be used to provide voltage support and power flow control,
increase transient stability and improve power oscillation
damping. Suitably located FACTS devices allow more
efficient utilization of existing transmission networks.
Among the FACTS family, the shunt FACTS devices such
as the STATCOM has been widely used to provide smooth
and rapid steady state and transient voltage control at points
in the network. This issue is even more critical in the case of
micro girds, since certain FACTS controllers, particularly
STATCOMs, are being considered as a possible solution for
some of the voltage and angle stability problems inherent to
these power grids. Consequently, typical STATCOM
models are validated here using system identification
techniques to extract the relevant electromechanical mode
information from time-domain signals. System identification
techniques are used to readily and directly compare fairly
distinct STATCOM models, thus avoiding matrix based
eigenvalue studies of complex system models and/or
modeling approximations.
In this paper, a STATCOM is added to the power
network to provide dynamic voltage control for the wind
farm, dynamic power flow control for the transmission lines,
relieve transmission congestion and improve power
oscillation damping. Simulation results show that the
STATCOM devices significantly improve the performance
of the wind farm and the power network during transient
disturbances.
II. WIND FARM AND ELECTRIC GENERATOR MODEL
In dynamic simulations, the electricity-producing wind
turbine is treated as a complex electromechanical system
consisting of the induction generator, the drive train system
and the rotating wind turbine.
The wind turbine model is developed based on the
steady-state power characteristics of the turbine. The
stiffness of the drive train is infinite and the friction factor
and the inertia of the generator coupled to the turbine [8].
The wind turbine model is developed based on the
steady state power characteristics of the turbine. The
stiffness of the drivetrain is infinite and the friction factor
and the inertia of the generator coupled to the turbine [8].
The mechanical power captured by wind turbine based on its
power utilization coefficient CP for a given wind velocity
VW and can be represented by:
Where Pt is the turbine power, ρ is the air density,
A is the swept turbine area, CP is the coefficient of
performance and Vw is the wind speed. The coefficient of
performance CP is nonlinear function of magnitudes: the
pitch angle β of rotor blades and tip speed ratio λ, which is
the quotient between the tangential speed of the rotor blade
tips and the undisturbed wind speed velocity [9].
Wind turbines use squirrel cage induction
generators are shown in Fig. 1. The stator winding is
connected directly to the grid and the rotor driven by the

Application of STATCOM to Improved Dynamic Performance of Power System
(IJSRD/Vol. 2/Issue 09/2014/128)
wind turbine. The power captured by the wind turbine is
converted into electrical power by the induction generator
and is transmitted to the grid by the stator winding. The
pitch angle is controlled in order to limit the generator
output power to its nominal value for high wind speeds. In
order to generate power the induction speed must be slightly
above the synchronous speed but the speed variation is
typically so small that the WTIG is considered to be affixed
speed wind generator.
Fig. 1: Wind turbine and induction generator
III. STATCOM MODEL
Shunt compensators are primarily used for bus voltage
regulation y means of providing or absorbing reactive
power; they are effective for damping electromechanical
oscillations [10]. Different kinds of shunt compensators are
currently being used in power systems, of which the most
popular ones are Static Var Compensator SVC and
STATCOM. In this work, only the STATCOM, which has a
more complicated topology than a SVC, is studied. The
STATCOM is a FACTS controller based on voltage sourced
converter VSC technology. A VSC generates a synchronous
voltage of fundamental frequency and controllable
magnitude and phase angle. If a VSC is shunt-connected to a
system via a coupling transformer as shown in Fig. 2, the
resulting STATCOM can inject or absorb reactive power to
or from the bus to which it is connected and thus regulate
bus voltage magnitudes [11]. The main advantage of a
STATCOM over a SVC is its reduced size, which results
from the elimination of ac capacitor banksand reactors;
moreover, a STATCOM response is about 10 times faster
than that of a SVC due to its turn-on and turn-off
capabilities.
Fig. 2: STATCOM power circuit
In Fig. 3, the coefficient k is proportional to the
modulation index ma, which for a two level inverter is k =
ma/2√2. It has been shown, by means of time domain
simulations that this TS model response is reasonably close
to that obtained from a detailed STATCOM model for
transients relatively afar from the controller [9].
Fig. 3: STATCOM transient stability model and its control
IV. STUDIED SYSTEM AND RESULTS
A wind farm consisting of six 1.5-MW wind turbines is
connected to a 25-kV distribution system exports power to a
120-kV grid through a 25-km 25-kV feeder as shown in
Fig.5a. The studied power system is simulated using
Simulink Matlab software package as shown in fig 5b. This
paper discussed the effect of speed variables on wind
turbines, effect of phase to ground fault on wind turbine #2,
and three phase-fault on wind turbine #2 on the system
studied to depicts the following: Three wind turbine rotor
speed, active, reactive power, and voltage on 25kV bus with
and without STATCOM.
Fig. 4: System Equipped by STATCOM using Simulink
matlab
A. With STATCOM

B. Without STATCOM
1) Effect of Speed Variables on Wind Turbines:
When the wind speed changes for each turbine as following,
C. Without STATCOM
D. With STATCOM
1) B25 bus
E. Without Statcom
F. With Statcom
V. CONCLUSION
Power system with wind farms performance can be
improved using FACTS devices such as STATCOM . The
dynamic model of the studied power system is simulated
using Simulink Matlab package sofware . To validate the
effect of the STATCOM controller of power system
operation, the system is subjected to different disturbances
such as faults and power operating conditions . The digital
results prove the powerful of the proposed STATCOM
controller in terms of Stability improvement, power swings
damping, voltage regulation, increase of power transmission
and chiefly as a supplier of controllable reactive power to
accelerate voltage recovery after fault occurrence.
REFERENCES
[1] Akhmatov, H.Knudsen, A.H. Nielsen,
J.K.Pedersen, And N.K. Poulsen, "A Dynamic
Stability Limit Of Grid Connected Induction
Generators", Pro. International Iasted Conference
On Power And Energy Systems, Marbella, Spain,
2000.
[2] L. holdsworth, X.G. Wu, J.B. EKanayake, and N.
Jenkins, "Comparison of fixed-speed and doubly-
fed induction generator wind turbines during power
system disturbances", IEE proc. C-Gener. Transm.
Distrib., vol. 150, no. 3, pp. 343-352, 2003.
[3] S.M. Bolik, "Grid requirments challenges for wind
turbines", Fourth International Workshop on large-
scale Integration of Wind Power and transmission
networks for Offshore Wind Farms, Oct .2003.
[4] L. Holdsworth, N.Jenkins, and G. Strbac,
"Electrical stability of large, offshore wind farms",

IEE seventh International Conference on AC-DC
power Transmission, pp.156-161-2001.
[5] X.G. Wu, A.Arulampalam, C. Zhan, and N.jenkins,
"Application of a static reactive power
compensator (STATCOM) and a dynamic braking
resistor (DBR) for the stability enhancement of a
large wind farms", Wind Engineering Journal, vol.
27, no.2, pp.93-106, March2003.
[6] Lie Xu Liangzhong Yao Sasse, C.," Comparison of
using SVC and STATCOM for wind farm
integration", International Conference on Power
System Technology, pp. 1-7, Oct 2006.
[7] N. G. Hingorani and L. Gyugyi, “Understanding
FACTS: Concepts and Technology of Flexible AC
Transmission Systems”, IEEE, New York, 2000,
ISBN 0-7803, pp. 3455-3458, 2000.
[8] EL-Moursi, M.S. and Sharaf ,A.M, “Novel
STATCOM controllers for voltage stablization of
wind energy scheme”, Int. J. Global Energy Issues,
vol. 26, 2006.
[9] F.G.R. de campos and A.A. Jr. penteado, ”Wind
Energy generation Simulation with asynchronous
generator connected to ENERSUL distribution
System”, IEEE/PES Transmission and Distribution
conference and Exposition, Latin America, pp.
149-154, 2004.
[10]Siegfried Heier, “Grid integration of wind energy
conversion systems”, Jon Wiley & Sons Ltd, 1998.
[11]SimPowerSystems User guide. Available
http://www.mathworks.com

APPLICATION OF STATCOM to IMPROVED DYNAMIC PERFORMANCE OF POWER SYSTEM

More Related Content

What's hot (20)

Viewers also liked (15)

Similar to APPLICATION OF STATCOM to IMPROVED DYNAMIC PERFORMANCE OF POWER SYSTEM (20)

More from ijsrd.com (20)

Recently uploaded (20)

APPLICATION OF STATCOM to IMPROVED DYNAMIC PERFORMANCE OF POWER SYSTEM