Modern power system transmission networks are becoming with increasing complexity due to growing demand and restrictions on building new lines. Losing stability is one of the major problem of such a modern power system following a disturbance. Transient stability control is an important concept which ensuring the stable operation of power system during the fault and large disturbances. FACTS technologies are found to be very effective in a power system transmission network for better controllability and increase power transfer capability without sacrificing the desired stability margin. This paper provides the comparative performance of STSTCOM, SVC and UPFC for improvement of transient stability of IEEE 9 bus power system. Static Synchronous Compensator and Static Var Compensator are the shunt devices of the Flexible AC Transmission Systems (FACTS) family. When the system voltage is low, STATCOM generates reactive power and when the system voltage is high then it absorbs reactive power whereas SVC is also operates as same as the STATCOM. SVC provides the fast acting dynamic compensation in case of severe fault. The UPFC is more effective Flexible AC Transmission Systems (FACTS) device for controlling active and reactive power flow in a transmission line and power oscillation damping by controlling its series and shunt parameters. To analysing the effects of STATCOM, UPFC and SVC on transient stability performance of the system by using the MATLAB/Simulink environment for multi- machine system. The performance of STATCOM, SVC and UPFC are compared with each other. The simulation results will show the effective and robustness of all the three FACTS devices. The better Flexible AC Transmission Systems (FACTS) device can be identified by this project for transient stability of IEEE 9 bus power system.

Keywords : FACTS, STATCOM, SVC and UPFC, Transient Stability and IEEE 9 bus power system.