Abstract: In a Power Systems the voltages drop to a very low magnitude when short circuit fault occurs. When voltage magnitude falls below the desired voltage called Voltage sag, which is one of the most severe problems to be dealt with as it causes severe disruptions and results in substantial economic loss. To control and compensate for the drop in voltage, Unified Power Flow Controller (UPFC) is used. UPFC is a FACTS device consisting of series and shunt converters where each is controlled by separate controllers. In this paper UPFC has been designed and incorporated in the system using MATLAB SIMULINK software. Fuzzy Logic Controller is designed for controlling the shunt converter. A simple test line is modeled and three phase to ground fault is applied on the system. The load voltage response with and without compensation is observed for the test system and compared to show that the voltage have been compensated as UPFC is implemented into the system and also the real and reactive power flow through the transmission line with and without compensation is observed which shows the efficient performance of UPFC.
Keywords: FACTS, UPFC, Fuzzy Logic Controller.