Design of Variable Structure Fuzzy Power System Stabilizer in Multimachine System

This paper introduces adaptive variable structure fuzzy controller as a power system stabilizer (AFPSS) used to damp inter-area modes of oscillation following large disturbances in power systems. In contrast to the conventional PSS, fuzzy-based stabilizers are more efficient because they cope with oscillations at different operating points. The proposed controller is a fuzzy-logic-based PSS that has the capability to tune its rule-base on line. The change in the fuzzy rule base is done using a variable-structure algorithm to achieve optimum performance. The adaptive algorithm of the proposed controller significantly reduces the rule base size due to its adaptively and improves its performance. This statement is confirmed by simulation results of a three-machine infinite-bus system under different operating points.