Power system stability compensation using Flexible A.C. Transmission System (FACTS) controllers

Abstract

This paper investigates power system stability compensation using FACTS controllers with the purpose of improving the security and dynamic control of power systems. FACTS controllers offer great opportunity to regulate the transmission of alternating current (AC), increasing the power flow in specific lines and responding almost instantaneously to system stability. Performance comparison and applications of different FACTS controller’s devices to power system stability and the benefits of utilizing FACTS in electrical transmission systems have been summarized and presented. It is observed that SVC controls can significantly influence nonlinear system behavior under high-stress operating conditions and improve the dynamic stability performance of a power system. STATCOM operation enables fast and coordinated response particularly under contingencies. This has allowed deferral of the construction of an additional line or the use of a second transformer bank, resulting in significant cost savings. TCSC controller can be designed to control the line impedance through the introduction of a thyristor-controlled capacitor in series with the transmission line, increase power transfer limits, and improve the stability margin significantly. TCSC controller provide 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. The UPFC has the ability to adjust the bus voltage, transmission line reactance, and phase angle between two buses, either simultaneously or independently.