A genetic algorithm optimized fuzzy logic controller for UPFC in order to damp of low frequency oscillations in power systems

Due to the lack of damping torque, power system disturbances such as step changes in input mechanical power, may lead to Low Frequency Oscillations (LFO). Power System Stabilizer (PSS) is a solution that has been used for many years in order to mitigate these oscillations. Flexible AC Transmission Systems (FACTs) is another solution for this problem. Among the FACTs devices, Unified Power Flow Controller (UPFC) has an excellent ability to control power flow, reduce sub-synchronous resonance, and increase transient and dynamic stability and therefore, may be used instead of PSS. In this paper, a Genetic Algorithm Optimized Fuzzy Logic Controller (GA-FLC) is used to control UPFC for damping low frequency oscillations. This study is applied to a single-machine infinite-bus (SMIB) PhillipsHeffron model by using MATLAB^®/ Simulink^® software. Simulation results explicitly show that the performance of the proposed GA-FLC Based UPFC is better than using PSS and a PI controlled UPFC in terms of damping LFO.