USING SSSC & STATCOM --IMPROVE TRANSIENT STABILITY--P & Q OSICALLATIONS

IJSRD - International Journal for Scientific Research & Development| Vol. 3, Issue 10, 2015 | ISSN (online): 2321-0613

Using SSSC & STATCOM --Improve Transient Stability-P & Q Oscillations R.Murali1 J. Rakesh Sharan2 M. Shiva Kumar3 P.G. Scholar 2Assistant Professor 3Associate Professor & HOD 1,2,3 Department of Electronics & Electrical Engineering 1,2,3 Sri Indu College of Engineering and Technology, Hyderabad, TS, India 1

Abstract— In a deregulated power system, the electric power demand is extending ordinary which may lead to overloads and loss of generation. Transient stability studies put a fundamental part in power systems, which give information related to the capacity of a power structure to stay in synchronism during major disturbances resulting from either the loss of generation or transmission facilities, sudden or sustained changes. The examination of transient quality is discriminating to work the power structure more secure and this paper focuses on growing the transient relentlessness using FACTS devices like Static Synchronous Series Compensator (SSSC) and static synchronous compensator (STATCOM). These FACTS contraptions are in a perfect world set on transmission structure using Sensitivity approach framework.

Key words: Frequent Pattern Mining, High Utility Itemset Mining, Transaction Database I. INTRODUCTION The power flow over a transmission line depends mainly on three important parameters, namely voltage magnitude of the buses (V ), impedance of the transmission line ( Z ) and phase angle between buses (θ ). The FACTS devices control one or more of the parameters to improve system performance by using placement and coordination of multiple FACTS controllers in large-scale emerging power system networks to also show that the achieve significant improvements in operating parameters of the power systems such as small signal stability, transient stability, damping of power system oscillations, security of the power system, less active power loss, voltage profile, congestion management, quality of the power system, efficiency of power system operations, power transfer capability through the lines, dynamic performances of power systems, and the load ability of the power system network also increased. As FACTS devices are fabricated using solid state controllers, their response is fast and accurate. Thus these devices can be utilized to improve the voltage profile of the system by using coordinated control of FACTS controllers in multimachine power systems in this work.

A. Generation of FACTS Controllers: The following generation of FACTS controllers for the development of FACTS controllers: 1) First Generation of FACTS Controllers: The following FACTS controllers such as Staic Var Compensator (SVC), Thyristor Controlled Series Capacitor (TCSC), and Thyristor Controlled Phase Shifting Transformer (TCPST) are developed in the first generation of FACTS controllers.

2) Second Generation of FACTS Controllers: The following FACTS controllers such as Static Synchronous Compensator (STATCOM), Static

Synchronous Series Compensator (SSSC), Unified Power Flow Controller (UPFC), and Interline Power Flow Controller (IPFC) are developed in the second generation of FACTS controllers.

B. Concepts of FACTS Technology: IEEE definition of FACTS and FACTS controllers are given as [1].

1) Flexible Ac Transmission System (Facts): Alternating current transmission systems incorporating power electronics based and other static controllers to enhance controllability and increase power transfer capability.

2) Facts Controller: Power electronics based system and other static equipment that provides control of one or more AC transmission system parameters.

In general, FACTS controllers can be divided in following categories ™ –

Series controllers such as Thyristor Controlled Series Capacitor (TCSC), Thyristor Controlled Phase Angle Regulators (TCPAR or TCPST), and Static Synchronous Series Compensator (SSSC) ™ – Shunt controllers such as Staic Var Compensator (SVC), and Static Synchronous Compensator (STATCOM) ™ – Combined series-series controllers such as Interline Power Flow Controller(IPFC) ™ – Combined series-shunt controllers such as Unified Power Flow Controller (UPFC).

This paper is based on Occurrence of a fault in a power system causes transients. To stabilize the system, The Flexible Alternating Current Transmission (FACTS) devices such as SSSC&STATCOM are becoming important in suppressing power system oscillations and improving system damping. The SSSC&STATCOM is a solid-state device, which can be used to control the active and reactive power. By using a SSSC&STATCOM the oscillation introduced by the faults, the rotor angle and speed deviations can be damped out quickly than a system without a SSSC&STATCOM. The effectiveness of SSSC&STATCOM in suppressing power system oscillation is investigated by analyzing their oscillation in rotor angle and change in speed occurred in the two machine system considered in this work. A proportional integral (PI) controller has been employed for the SSSC&STATCOM. It is also shown that a SSSC&STATCOM can control independently the real and reactive power flow in a transmission line. A MATLAB simulation has been carried out to demonstrate the performance of the SSSC&STATCOM in achieving transient stability of the two-machine five-bus system.

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Using SSSC & STATCOM --Improve Transient Stability-P & Q Oscillations (IJSRD/Vol. 3/Issue 10/2015/090)

II. INTRODUCTION TO STATCOM AND SSSC CONTROLLERS A. Static Compensator (STATCOM) It is a device connected in derivation, basically composed of a coupling transformer, that serves of link between the electrical power system (EPS) and the voltage synchronous controller (VSC), that generates the voltage wave comparing it to the one of the electric system to realize the exchange of reactive power. The control system of the STATCOM adjusts at each moment the inverse voltage so that the current injected in the network is in quadrature to the network voltage, in these conditions P=0 and Q=0. In its most general way, the STATCOM can be modeled as a regulated voltage source Vi connected to a voltage bar Vs through a transformer. The STATCOM uses a VSC interfaced in shunt to a transmission line. In most cases the DC voltage support for the VSC will be provided by the DC capacitor of relatively small energy storage capability hence, in steady state operation, active power exchanged with the line has to be maintained at zero, as shown symbolically in the Figure 3.

Fig. 3: SSSC Connections.

Again, the active power exchanged with the line has to be maintained at zero hence, in steady state operation, SSSC is a functional equivalent of an infinitely variable series connected capacitor. The SSSC offers fast control and it is inherently neutral to sub-synchronous resonance.

C. Simulation Circuit:

BUS-1: Voltage and currents Fig. 3: STATCOM Connections.

With the active power constraint imposed, the control of the STATCOM is reduced to one degree of freedom, which is used to control the amount of reactive power exchanged with the line. Accordingly, a STATCOM is operated as a functional equivalent of a static VAR compensator; it provides faster control than an SVC and improved control range.

B. Static Synchronous Series Compensator (SSSC) This device work the same way as the STATCOM. It has a voltage source converter serially connected to a transmission line through a transformer. It is necessary an energy source to provide a continuous voltage through a condenser and to compensate the losses of the VSC. A SSSC is able to exchange active and reactive power with the transmission system. But if our only aim is to balance the reactive power, the energy source could be quite small. The injected voltage can be controlled in phase and magnitude if we have an energy source that is big enough for the purpose. With reactive power compensation only the voltage is controllable, because the voltage vector forms 90ยบ degrees with the line intensity. In this case the serial injected voltage can delay or advanced the line current. This means that the SSSC can be uniformly controlled in any value, in the VSC working slot. The Static Synchronous Series Compensator (SSSC) uses a VSC interfaced in series to a transmission line, as shown in the Figure 4.

BUS-1: Active and Reactive power

BUS-2: Voltage and currents

BUS-2: Active and Reactive power

BUS-3: Voltage and currents

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Using SSSC & STATCOM --Improve Transient Stability-P & Q Oscillations (IJSRD/Vol. 3/Issue 10/2015/090)

BUS-3: Active and Reactive power

BUS-4: Voltage and currents

BUS-4: Active and Reactive power

[3] L. Gyugyi, 1994, “Dynamic Compensation of AC Transmission Line by Solid State Synchronous Voltage Sources,” IEEE Transactions on Power Delivery, 9(22), pp. 904-911.

[4] Muhammad Harunur Rashid, “Power Electronics – Circuits, Devices, and Applications, “PRENTICE HALL, Englewood Cliffs, New Jersey.07632, 1988.

[5] Amany E L – Zonkoly, “Optimal sizing of SSSC Controllers to minimize transmission loss and a novel model of SSSC to study transient response, “Electric power Systems research 78 (2008) 1856 – 1864.

[6] B.N.Singh, A.Chandra, K.Al-Haddad and B.Singh, “Performance of sliding-mode and fuzzy controllers for a static synchronous series compensator, “IEE Proceedings onhe no. 19990072, IEE, 1999.

[7] F. Wang, “Design of SSSC Damping Controller to Improve Power System Oscillation Stability, “0-78035546-6/99/$10.00 © 1999 IEEE. [8] A. Kazemi, M. Ladjevar DI and M.A.S. Masoum, “Optimal Selection of SSSC Based Damping Controller Parameters for Improving Power System Dynamic Stability Using Genetic Algorithm “Iranian Journal of Science & Technology, Transaction B, Engineering, Vol. 29, No.B1 Printed in the Islamic Republic of Iran, 2005 © Shiraz University.

[9] I. S. Jacobs and C. P. Bean, “Fine particles, thin films and exchange anisotropy,” in Magnetism, vol. III, G. T. Rado and H. Suhl, Eds. New York: Academic, 1963, pp. 271–350.

III. CONCLUSION The electric power demand is extending ordinary which may lead to overloads and loss of generation. Transient stability studied put a fundamental part in power systems, which give information related to the capacity of a power structure to stay in synchronism during major disturbances resulting from either the loss of generation or transmission facilities, sudden or sustained changes. The examination of transient quality is discriminating to work the power structure more secure and this paper focused on growing the transient relentlessness using FACTS devices like Static Synchronous Series Compensator (SSSC) and static synchronous compensator (STATCOM). These FACTS contraptions are in a perfect world set on transmission structure using Sensitivity approach framework.

REFERENCES [1] Gyugyi, L. (1989). “Solid-state control of AC power transmission.” International Symposium on Electric Energy Conversion in Power System, Capri, Italy, (paper No. T-IP.4).

[2] Sen, K.K. (1998). “SSSC-static synchronous series compensator: theory, modeling and publications.”

IEEE Trans. Power Delivery. Vol. 13, No.1, January, PP. 241-246.

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