Abstract: The characteristics of FACTS controllers such as Fixed Capacitor- Thyristor Controlled Reactor (FC-TCR) Thyristor Controlled Voltage Regulator (TCVR) and Unified Power Flow Controller (UPFC) used for reactive power compensation in a transmission network are analyzed and the operation and simulation results are presented in this stduy. The control strategy for Real and Reactive powers of the transmission line using FC-TCR and UPFC and the voltage regulation using TCVR are described. In case of FC-TCR, the control is achieved by controlling the current through the TC reactor by varying the phase of the thyristor switch. In TCVR system, the power flow in the line is controlled by voltage regulation method. Thus, by voltage boosting in the transmission line, the power flow in the line is increased. This method uses thyristor based control and thus overcomes the difficulties of a conventional type on-load tap changer. The control in case of UPFC is obtained by replacing the traditional UPFC consisting of shunt converter and series converter with a current source and a voltage source model. The reactive power supplied to the load can be increased by increasing the magnitude of shunt current. The power factor can be increased by increasing the angle of injected voltage. The circuit models of FC-TCR, TCVR and UPFC systems are developed and the respective systems are simulated successfully using these models. The simulation results are presented to demonstrate the performance of the controllers