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Stability Improvement Analysis of Wind Farm by
SVC in Matlab/ Simulink during Fault
Priyanka Sharma1, Abhishek Jain2, Kamal Kumar Ranga3, Vikas Yadav4, Sandeep Ranga5
1 M. Tech. Scholar, Department of Electrical Engineering, Ganga Institute of Technology and Management,
Kablana, Jhajjar, Haryana, INDIA
2 Assistant Professor, Department of Electrical Engineering,, Ganga Institute of Technology and
Management, Kablana, Jhajjar, Haryana, INDIA
3 Assistant Professor, Department of Computer Science & Engineering, Ganga Institute of Technology and
Management, Kablana, Jhajjar, Haryana, INDIA
4 Assistant Professor, Department of Electrical Engineering,, Ganga Institute of Technology and
Management, Kablana, Jhajjar, Haryana, INDIA
5 Lab Instructor, Department of Electrical Engineering,, Ganga Institute of Technology and Management,
Kablana, Jhajjar, Haryana, INDIA
Abstract : This paper studies the use of a Static Var Compensator (SVC) with wind farms for the
purpose of stabilizing the grid voltage after a grid-side disturbance viz., a three phase short circuit
fault. System stability of wind farms based on squirrel cage induction generators (SCIG) are
investigates. Due to the nature of asynchronous operation, system instability of wind farms based
on SCIG is largely caused by the excessive reactive power absorption by SCIG after fault due to
the large rotor slip gained during fault. To analyze the performance of the SVC, an induction
generator based wind farm has been considered. The complete digital simulation of the SVC
incorporated into the power system is performed in the MATLAB/SIMULINK environment and
the results are presented to validate the feasibility of the proposed topology.
सार:यह पत्र एक ग्रिड ओर अशाांति अर्ााि के बाद ग्रिड वोल्टे ज स्थर्र करने के प्रयोजन के लिए पवन फार्मों के सार्
एक स्थर्र वार कम्पेसाटर (एसवीसी) के उपयोग का अध्ययन करिा है ., एक िीन चरण शॉटा सर्काट गििी.
ग्रगिहरी पपांजरे प्रेरण जनरे टर (SCIG) के आधार पर पवन फार्मों की प्रणािी की स्थर्रिा की जाांच कर रहे हैं.
अिुल्यकालिक आपरे शन की प्रकृति के कारण, SCIG के आधार पर पवन फार्मों की प्रणािी अस्थर्रिा बडे पैर्माने
पर होने के कारण गििी के दौरान प्राप्ि की बडी रोटर पची को गििी के बाद SCIG द्वारा अत्यग्रधक
प्रतिर्ियाशीि शस्ति अवशोषण के कारण होिा है . एसवीसी के प्रदशान का पवश्िेषण करने के लिए, एक प्रेरण
जनरे टर आधाररि हवा खेि र्में र्माना गया है . बबजिी व्यवथर्ा र्में शालर्मि एसवीसी का परू ा डडस्जटि अनक
ु रण
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MATLAB / simulink वािावरण र्में र्कया जािा है और पररणार्म प्रथिापवि टोपोिॉजी की व्यवहायािा को र्मान्य
करने के लिए प्रथिुि कर रहे हैं
Keywords: Induction Generator, Wind farm, SVC, System Stability, Flexible AC Transmission
Systems (FACTS).
I. INTRODUCTION
With the Asynchronous wind generators as research object, this paper analyzes the problems of the
voltage stability and the generation mechanism of the reactive power compensation during the wind
farms connected operation. The wind farms supply the active power to the grid when the wind turbines
are connected to the grid, but at the same time, the reactive power is absorbed from grid, which would
bring the reactive burden to the grid. Therefore, it is necessary to compensate the reactive power for gridconnected wind farm to eliminate the effects of voltage fluctuations which is caused by reactive power
loss in grid and would lead to tripping operation of turbines. And the sufficient amount of reactive power
compensation is needed to improve the safety and stable operation of the power grid.
Currently, the method of connecting the asynchronous generator and capacitor banks in parallel permits is
mostly used for wind farm reactive power compensation. However, with the rapid development of power
electronics technology, this traditional reactive power compensation shows some obvious drawbacks and
connecting the Flexible AC Transmission System (FACTS) to the wind farm to improve the operation
characteristics become a necessity. And in this paper, the method with Static Synchronous Compensator
(SVC) is proposed to compensate the reactive power in dynamic process to improve the operation
condition of wind farm [3].
II. AN OUTLINE OF FACTS DEVICES
Eventually FACTS devices found applicability in the wind power industry. It was found that providing
earlier Wind Power Plants with some external reactive compensation devices such as SVC or
STATCOM, the grid compliance can be met, and thus the Wind Power Plants could remain connected to
the power system without stability risks [4].
III A Static VAR Compensators (SVC)
SVC’s being dated from early 70’s, have the largest share among FACTS devices. They consist of
conventional thyristors which have a faster control over the bus voltage and require more sophisticated
controllers compared to the mechanical switched conventional devices. SVC’s are shunt connected
devices capable of generating or absorbing reactive power. By having a controlled output of capacitive or
inductive current, they can maintain voltage stability at the connected bus [4].
Fig. 1 shows these configurations: the Thyristor Controlled Reactor (TCR), the Thyristor Switched
Reactor (TSR) and the Thyristor Switched Capacitor (TSC) or a combination of all three in parallel
configurations. The TCR uses firing angle control to continuously increase/decrease the inductive current
whereas in the TSR the inductors connected are switched in and out stepwise, thus with no continuous
control of firing angle [4].
Usually SVC’s are connected to the transmission lines, thus having high voltage ratings. Therefore the
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SVC systems have a modular design with more thyristor valves connected in series/ parallel for extended
voltage level capability [4].
Fig. 1: svc configurations and its i-v characteristics.
To provide the needed reactive power generation/consumption in the network SVC’s adjust the
conduction periods of each thyristor valve. For an SVC consisting of one TCR and one TSC, assuming
that both reactor and capacitor have same pu ratings then the following scenarios can occur:



Reactive power is absorbed when the thyristor valve on the reactor leg is partially or fully
conducting and the capacitor leg switch is off.
Reactive power is generated when the thyristor valve on the reactor leg is in partial or no
conduction mode and the capacitor leg switch is on.
No reactive power is generated/absorbed if both the thyristor valve is not conducting and the
capacitor switch is off.
The voltage-current (V-I) characteristic of an SVC with the two operating zones is shown in Fig.1. A
slope around the nominal voltage is also indicated on the V-I characteristic, showing a voltage deviation
during normal operation, which can be balanced with maximum capacitive or inductive currents. As the
bus voltage drops, so does the current injection capability. This linear dependence is a significant
drawback in case of grid faults, when large amount of capacitive current is needed to bring back the bus
nominal voltage [4].
The technology of SVC with thyristor valves is becoming outdated mainly due to the slow time
responses, of injected current dependence on bus voltage and low dynamic performance.
IV. TEST SYSTEM
The single line diagram of a test system employed in this study is shown in fig. drawn below. The
network consists of a 33 kV,
50 Hz, grid supply point. A wind farm of 110 kW is integrated with a power grid of 33 kV by a three
phase transformer of 400V/33 kV, 110 kVA. There are two loads in the system; one load of 50 kW which
is connected to 33 KV grids through another step down transformer of 33 kV/400 V, 250 kVA and
another load of 2 kW at 6 KM away from each other. The 33 KV, 6 KM long line is modeled as line.
Used generator in this model is squirrel cage induction generators and stator windings are directly
connected to the grid. This grid is used to study and analyze machine and wind farm stability. Dynamic
compensation of reactive power is provided by a SVC located at the point of wind farm connection. Here
we study using MATLAB Simulation:
1. Induction generator stability conditions study without using SVC.
2. Induction generator stability conditions study with using SVC.
In this study, initially, Induction generators required reactive power is considered by capacitor
bank connected to 400V terminals at 400 KVAR rate. It's obvious that in system different conditions
more reactive power demand is provided by grid. A 3- Phase short circuit is occurred at 1.0 seconds to
3.5 seconds.
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Fig.2: Single Line Diagram Of Test System
SIMULATION MODEL
Fig 3: Simulink Model Of Wind Farm With Svc
V. RESULTS AND ANALYSIS
When we consider the above model under fault condition the system become unbalance and uncontrolled
in case of normal operating condition the output waveform is as shown in Fig. 4 during fault condition
without use of SVC.
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Fig.4: Output Waveform Under Fault Condition When Capacitor Bank In Use
Fig. 5 shows the voltages at Bus-1 and Bus-2 (voltage vs time) during the operation of without SVC
located at the point of wind farm connection.
Fig. 5: voltages at bus-1 and bus-2 without svc
Fig. 6: active and reactive power at bus-2 without svc
To overcome the difficulties arrives in case of power control by only use of capacitor bank the following
model is structured by using SVC. The comparative result i.e. rotor current vs time, stator current vs time,
rotor speed vs time & electromagnetic torque vs time (sec) has been shown in Fig. 9 for the system.
Fig.7: Power Flow Output Waveform Under Fault Condition When Svc In Use
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Fig. 8 shows the voltages at Bus-1 and Bus-2 (voltage vs time) during the operation of with SVC located
at the point of wind farm connection. It is shown that the voltage at Bus-2 drops to very low value of 0.62
pu due to insufficient reactive power but this voltage get improved to 1.0 pu when SVC is incorporated in
system. Thus the voltage and hence Power Quality Improvement/ Stability with Static Compensator on
Grid Integration of Wind Energy System is improved.
Fig. 8: voltages at bus-1 and bus-2 with svc
Fig. 9: active and reactive power at bus-2 without svc
The following results has been observed:
RATED POWER
110 KW
STATOR VOLTAGE
400 V
Rs (stator resistance)
0.01481 pu
Rr (rotor resistance)
0.008464 pu
Ls (stator inductance)
0.04881 pu
Lr (rotor inductance)
0.04881 pu
Lm(mutual inductance)
2.241 pu
Number of pole pairs
2
Inertia constant
0.258
SVC
110 KVA
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Table 1. Parameters of simulated induction generator
VI. CONCLUSION
In our study we consider the squirrel cage induction generator based wind turbine. We consider the four
parameters of it i.e. rotor current, stator current, rotor speed and electromagnetic torque and the effect of
three phase fault is consider by using MATLAB SIMULATION. As we know the important
characteristics of induction generator that it gives active power to grid and absorbs reactive power from
the grid. So to fulfill the needs of reactive power the most suitable candidate of FACTS devices is SVC.
Results clearly show that SVC improve the stability of the wind farm system.
निष्कर्ष: हमारे अध्ययि में हम गिलहरी प ज
िं रे प्रेरण जिरे टर आधाररत
वि टरबाइि
र पवचार करें . हम
MATLAB सिमल
ु ेशि का उ योि करके र पवचार कर रहा है इिके बारे में चार मा दिं डों यािी रोटर वतषमाि,
स्टे टर वतषमाि, रोटर िनत और पवद्युत टोक़ और तीि चरण िलती के प्रभाव र पवचार करें . हम यह गिड को
िक्रिय शक्तत दे ता है और गिड िे प्रनतक्रियाशील शक्तत अवशोपर्त क्रक प्रेरण जिरे टर की महत्व ूणष पवशेर्ताओिं
जािते हैं. इिसलए तथ्यों उ करणों के िबिे उ युतत उम्मीदवार एिवीिी है प्रनतक्रियाशील बबजली की जरूरतों को
रू ा करिे के सलए. ररणाम स् ष्ट रू िे एिवीिी हवा खेत प्रणाली की क्स्िरता में िध
ु ार बताते हैं.
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