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Increase Power Transfer Capability and Controlling Line Power Flow in Power System Installed the FACTS Vjollca Komoni, Isuf Krasniqi *, Gazmend Kabashi**, Avni Alidemaj** Faculty of Electrical and Computer Engineering, University of Prishtina, Kosovo Transmission System and Market Operator of Kosovo, KEK Energetic Corporation of Kosovo
Abstract-- This paper presents possibility to increase power system capability and controlling line power flow in power system with FACTS controllers. FACTS enhance power system performance, improve quality of supply and also provide an optimal utilization of existing resources. Various FACTS controllers devices, especially SVC and STATCOM, enable load flow on parallel circuits to be optimized and controlled, with a minimum of power wheeling, the best possible utilization of line, and a minimizing of overall system losses at the same time. The objectives were to determine the power transfer capability in power system, identify means of increasing the transfer limit, and test the potential application of FACTS devices. The paper describes the analytical approach, computational tools and simulations models. Keywords: Power systems performance, load flow optimized and controls, FACTS controllers’ devices, SVC and STATCOM, transmission efficiency.
I. INTRODUCTION
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Aximum power transfer in transmission system are often determined by steady-state ( thermal or voltage), transient stability and/or voltage stability limits. These constraints prevent full utilization of available transmission resources. Therefore, FACTS (flexible ac transmission system) technology can provide power controllers to enhance the utilization of existing transmission system and reduce the steady-state and transient stability limits [2]-[4]. Traditionally, fixed or mechanically switched shunt and series capacitors, reactors and synchronous generators were being used to solve much of the problem. However there are restrictions as to the use of these conventional devices. This desired performance was not being able to achieve effectively. Wear and tear in the mechanical components V. Komoni is with the Faculty of Electrical and Computer Engineering, University of Prishtina, Kosovo (
[email protected]). I. Krasniqi is with the Faculty of Electrical and Computer Engineering, University of Prishtina, Kosovo ( ). G. Kabashi is with the Transmission System and Market Operator of Kosovo, (
[email protected]). A. Alidemaj is with Energetic Corporation of Kosovo, ( )
and slow response were the heart of the problems. For these needs requires the alternative technology made of solid state devices with fast response characteristics. There is achieved with a rapid development of power electronics and semiconductors technologies in the last decades, a new family devices with the common name flexible AC transmission systems (FACTS) is becoming available. Facts controllers have been applied in utilities around the world since 1970s, when the first used family of FACTS named Static Var Compensator (SVC). Since then more research and development of FACTS controllers was done [10]. This paper presents a possibility to increase power transfer capability and controlling line power flow in our transmission system. The aims of this study were to determinate the line power transfer capability in our power transmission system, identify means of increasing transfer limit, and analyses possibility of use FACTS device. Paper present the results of simulation which are analyze and study the increase power transfer capability and controlling line power flow in power system with SVC and STATCOM. The model Kosovo power system is studies and the developed in PSS/E 32. Simulations are carried out for steady state calculation and dynamic simulation. By means of steady state calculation are analyzed the effect of FACTS in operation performance of transmission power system. While, by means of dynamic calculation is analyzed the response of FACTS device in small or large disturbance in system.
II. FACTS DEVICES In the power system, the FACTS device may be used to achieve several goals. FACTS controllers can be used for various applications to enhance power system performance. The greatest advantages of using FACTS controllers is that can be used in the three states of the power system> (1) Steady state, (2) Transient and (3) Post transient steady state. In steady state applications of FACTS controllers includes voltage control (low and high), increasing the thermal loading, loop flows control. SVC and STATCOM can be used for voltage control while TCSC is more suited for loop flow control and power flow control. Dynamic application of FACTS controllers includes transient stability improvement, oscillation damping and voltage stability enhancement. The most important of
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FACTS application is the capabilities expected to be able to reduce the impact of primary disturbance. The impact reduction of contingencies can be achieved through dynamic voltage support (STATCOM) dynamic flow control (TCSC) or both with the use of UPFC. SVC Schematic diagram of a static var compensator is shown in fig.1. SVC can provide voltage and reactive power control by varying its shunt reactance. Two popular configurations of SVC are the combination of fixed capacitor and Thyristor Controlled Reactor (TCR) and the combination of Thyristor Switched Capacitor (TSC) and harmonic filters. It might also include mechanically switched shunt capacitors (MSCs), and then is used the term static var system.
HV bus Q SVC
STATCOM STATCOM is one of the important shunt connected Flexible AC Transmission Systems (FACTS) controllers to control power flow and make better transient stability [7]. The voltage-sourced converter (VSC) is the basic electronic part of a STATCOM, which converters the dc voltage into a three-phase set of output voltages with desired amplitude, frequency, and phase. A STATCOM device, as shown in Fig. 3 consist of dc capacitor that is shunt-connected to the ac network by means of high-speed electronic switches. Sufficient number of thyristor bridges, it is possible for a convert to synthesize a controlled ac voltage with acceptable harmonic content behind the convert transformer reactance. It regulates voltage at its terminal by changing the amount of reactive power in or out from the power system. When system voltage is low, the STATCOM inject reactive power. When system voltage is high, it absorbs reactive power.
MV bus
Transmission Line If V0 =V, i=0 V If V0 >V, i=0 is Capacitive If V0
