Simplified Fuzzy Logic Controller and Its Application as a Power System Stabilizer

A simplified fuzzy logic controller (SFLC) with a significantly reduced set of fuzzy rules, small number of tuning parameters and simple control algorithm and structure is presented. The SFLC is derived from a two-dimensional and symmetrical rule table commonly used in fuzzy control applications. In the phase-plane, the required control action magnitude is proportional to the distance from the state of the system to the switching line (defined by the desired zero consequence). Based on the SFLC, a simplified power system stabilizer (SFLPSS) is designed and applied to a single machine-infinite bus system. Simulation studies are carried out to show that the proposed SFLPSS, with a considerably reduced rule base, is able to provide the same response as a fuzzy controller with the original set of fuzzy rules. The results also show the effectiveness of the proposed PSS in damping power system oscillations, as compared to a conventional PSS.