TRANSIENT STABS ENHANCEMENT OF MULTIMACHINE POWER SYSTEM USING FACTS DEVICES

Abstract

Power system engineers are currently facing challenges to increase the power transfer capabilities of existing transmission system. Flexible AC Transmission system (FACTs) controllers can balance the power flow and thereby using the existing power system network most efficiently. Because of their fast response FACTs controllers can also improve the stability of an electrical power system by helping critically disturbed generators to give away the excess energy gained through the acceleration during fault. Thyristor controlled series compensator (TCSC) is an important device in FACTs family and is widely recognized as an effective and economical means to solve the power system stability problem. TCSC controller, the first generation of FACTs, can control the line impedance through the introduction of a thyristor-controlled capacitor in series with the transmission line. TCSC is used as series compensator in transmission system. The TCSC controller can be designed to control the power flow, to increase the transfer limits or to improve the transient stability. The TCSC controller can provide a very fast action to increase the synchronization power through quick changing of the equivalent capacitive reactance to the full compensation in the first few cycles after a fault, hence subsequent oscillations are damped. In the present work TCSC controller for multi-machine power system is designed using SIMULINK (a software tool associated with MATLAB). Multi-machine power system with turbine and governing system is modeled. Modeling is done for system with TCSC controller. Effect of TCSC controller parameter variation on rotor angle is also studied. A detailed analysis is conducted for the proposed controller for different fault clearing time. It has been observed that TCSC controller can improve the stability margin significantly. TCSC controller provides variable impedance, which is required for the compensation. The presented controller is suitable only in capacitive zone. For the transition from a capacitive vernier mode to bypass mode the TCSC controller can be modeled with detailed dynamics.