Transient stability improvement of SMIB with unified power flow controller

The focus of this paper is on a FACTS device known as the Unified Power Flow Controller (UPFC), which can provide simultaneous control of basic power system parameters like voltage, impedance and phase angle. In this research work, two simulation models of single machine infinite bus (SMIB) system, i.e. with & without UPFC, have been developed. These simulation models have been incorporated into MATLAB based Power System Toolbox (PST) for their transient stability analysis. These models were analysed for three phase fault at different locations, i.e. at the middle and receiving end of the transmission line keeping the location of UPFC fixed at the receiving end of the line. Transient stability was studied with the help of curves of fault current, active & reactive power at receiving end, shunt injected voltage & its angle, series injected voltage & its angle and excitation voltage. With the addition of UPFC, the magnitude of fault current reduces and oscillations of excitation voltage also reduce. Series and Shunt parts of UPFC provide series and shunt injected voltage at certain different angles. Therefore, it can be concluded that transient stability of SMIB is improved with the addition of Unified Power Flow Controller.