A fuzzy control scheme for nonlinear systems and its application to power systems

The Takagi-Sugeno model (T-S model) based fuzzy control scheme for nonlinear systems is presented in this paper. In the T-S fuzzy model, a nonlinear system is represented with a set of fuzzy rules which describe the local linear dynamics. Then the parallel distributed compensation (PDC) design is employed in the fuzzy controller design. Linear optimal control is used in the derivation of each control rule. The overall fuzzy controller is a fuzzy blending of each individual linear controller. Quadratic stability of the overall nonlinear control system can be checked and ensured with H^∞ control theory. The fuzzy control scheme is applied to thyristor-controlled series compensator control in power system transients. Digital simulations with NOTOMAC software have demonstrated that the fuzzy control scheme is superior to other conventional control methods. The fuzzy controller effectively improves power systems transient stability and very quickly damp power swings