This paper presents the performance of intelligent fuzzy-based coordinated control for Automatic Voltage Regulator (AVR) and Power System Stabilizer (PSS) to prevent losing synchronism after a major sudden fault and to achieve appropriate post-fault voltage level in multi-machine power systems. The AVR and PSS gains can adaptively change to guarantee the power system stability after faults. To change in AVR and PSS gains at least one significant generator in each area is equipped with a fuzzy logic unit. The fuzzy logic unit accepts normalized deviation of terminal voltage and normalized phase difference as inputs and generates the favorable gains for AVR and PSS. The work describes the construction of appropriate fuzzy membership functions and rules for best tuning of gains. The proposed fuzzy control methodology has been applied to 11-bus 4-generator power system test case. Simulation results illustrate the effectiveness and robustness of this fuzzy-based coordinated control.
