AN ADAPTIVE FUZZY-LOGIC POWER-SYSTEM STABILIZER

The paper presents an adaptive fuzzy logic power system stabilizer (PS S) design for damping oscillatory electromechanical modes of oscillati ons and enhancing the first-swing synchronous stability margins. The n ovel design utilizes a multivariable damping signal vector consisting of machine speed deviation, rate of speed deviation, and voltage devia tion. The design is based on a multizonal PID structure and fuzzy logi c variable-gain scheduling to optimize the damping action. The fuzzy l ogic PSS is proposed for use in parallel with the conventional analog type PSS with added simple switching criteria. The two PSS blocks can be allowed independent, sequential, and/or combined operation with dif ferent effective stabilizing weighting. The paper investigates an indi vidual conventional PSS, a rule based fuzzy PSS, and hybrid operation. The parallel operation of a conventional PSS and a fuzzy logic one pr ovides optimal sharing of the camping action under small- as well as l arge-scale generation-load mismatch or variations in external network topology due to fault or switching conditions.