Power System Stability Improvement using Flexible A.C Transmission System (FACTS) Controllers

This article studies power system stability improvement using Flexible Alternating Current Transmission System (FACTS) controllers. FACTS controllers are controllable devices that can efficiently regulate AC transmission, boost power transfer in a given line and react instantaneously to system stability issues. The performance, operations and control characteristics of four types of FACTS controllers – Static VAR Compensator (SVC), Thyristor Controlled Series Compensator (TCSC), Static Compensator (STATCOM), and Unified Power Flow Controller (UPFC) – are analysed. The study includes applications and comparative methods for reactive power compensating devices in terms of stability and the advantages of using them in electrical transmission systems. Results show that SVC provides voltage control, minimises temporary overvoltage, reduces voltage flicker caused by non-linear loads, and improves the power transfer capability of transmission systems. STATCOM demonstrates faster response and better performance during transients, provides voltage control, VAR compensation, voltage stability, better damping oscillations and maintains stable voltage even in very weak AC systems. TCSC acts quickly and is a cost-effective solution for transient stability, dynamic and steady state stability. VAR compensation, damping of oscillations and voltage stability in long transmission lines; it increases the power transfer limits and significantly improves the stability margin. UPFC offers active and reactive power control, voltage control, VAR compensation, damping of oscillations, transient and dynamic stability, voltage stability, real-time control and dynamic compensation of AC transmission systems. It can adjust bus voltage, transmission line reactance, and phase angle between two buses simultaneously, providing independently controllable shunt reactive compensation.