Design of a robust PSS using an indirect adaptive type-2 fuzzy sliding mode for a multi-machine power system

A new indirect adaptive type-2 fuzzy sliding mode controller as a power system stabilizer (PSS) is proposed for damping low frequency power oscillation of interconnected power system and capable of performing well for a wide range of variations in system parameters and/or operating conditions. The proposed controller design is based on the integration of sliding mode control (SMC) and Adaptive type-2 fuzzy control. The type-2 fuzzy logic system is used to approximate the unknown system function and PI control term is used to eliminate chattering action in the design of sliding mode control. Using Lyapunov stability theory, the adaptation laws are developed to make the controller adaptive to take care of the changes due to the different operating conditions occurring in the power system and guarantees stability converge. The robustness of the proposed stabilizer has been tested on a two-area four machine power system. Nonlinear simulation studies show the best performance of the proposed stabilizer and confirm its superiority over adaptive type-2 fuzzy synergetic (AFSPSS), adaptive type-2 fuzzy (AFPSS) and the conventional (CPSS) stabilizers.