Transient Stability Improvement with Unified Power Flow Controller Using Fuzzy Logic and ANFIS Approach

Transient stability is an important aspect in planning and operation of an electric power system. The application of Fuzzy logic and Adaptive Neuro Fuzzy Inference System (ANFIS) approach to power system problems has received increased attention in recent years. This paper investigates the fuzzy logic based Unified Power Flow Control (UPFC) methods namely in-phase voltage control and quadrature voltage control in improving transient stability of power system using energy function method. The potential of the two control methods in transient stability enhancement is identified in Single Machine Infinite Bus System (SMIB) system. UPFC is connected in SMIB system in middle of the transmission line. Results indicate that significant reductions in the transient swings are obtained with UPFC. The result shows that the transient stability margin is substantially improved with in-phase voltage control higher than the quadrature voltage control.