Abstract
FACTS devices are used to control the voltage profile and stability of power system by improving transient and dynamic stability. Particle swarm optimization (PSO) technique is used in place of Genetic Algorithm (GA) for minimization of losses and simulation process. There are several types of FACTS devices but we have discussed only SVC (Static Var Compensator), Thyristor Controlled Series Compensator (TCSC) and Unified Power Flow Controller (UPFC) for this purpose. The mathematical model of these FACTS devices are also discussed with their applications in 3 machine 9 bus system.