Optimal placement of TCSC for improvement of static voltage stability

Voltage instability in power system is a major issue in electrical power system operation. Voltage instability occurs mainly due to deficit of reactive power at load buses during some contingency or under increased loading condition. Flexible AC Transmission System (FACTS) devices can improve the voltage stability with reduction of losses and generation cost. Thyristor Controlled Series Compensator (TCSC) is a series FACTS device, which can improve voltage stability with improved power transfer capability of the transmission line. Like other FACTS devices, TCSC is costly and it is required to find its optimal location and size for improvement of voltage stability. Here Particle Swarm Optimization (PSO) and PSO with time varying acceleration coefficient (PSO-TVAC), used to locate a TCSC of an optimum rating for voltage stability improvement of power system. Line Stability Index (LSI) is considered here for optimization purpose which provides the information about the stability condition of a power system and its proximity to voltage collapse. The analysis has been demonstrated on a standard IEEE 6-bus system with some modification in load data and overloading condition using MATLAB. PSO-TVAC gives fast convergence than PSO.