Combination of Fuzzy and Optimal Controls for Stabilizing Power Systems

Abstract

Optimal control has been discussed for models, in general, obtained by linearizing power systems. However, it is known that the control has not been effective for large disturbances. Fuzzy control, in which the nonlinearity of a system can be considered, has been recently studied in many fields of engineering. In this paper, two types of combination controls by means of fuzzy and optimal controls are proposed. The first type is a control combining two optimal controls, which can be obtained from two linear models given by linearizing a power system, through fuzzy theory. For the second one, fuzzy control is fundamentally used and optimal control is applied to fuzzy control rules around the stable equilibrium point. It is shown that these combination controls are better to improve the transient stability for large dinturbances in power systems than fuzzy only or usual optimal control. These controls are applied to the stabilizing control problem for a multimachine power system taking into account AVR and GOV.