Design of suboptimal H/spl infin/ excitation controllers

This paper presents a method to design suboptimal robust excitation controllers based on H/spl infin/ control theory. The suboptimal controller results from additional constraints that are imposed on the standard optimal H/spl infin/ solution. Global stability constraints are incorporated into the H/spl infin/ algorithm to ensure stability of the interconnected power system under decentralized control. Furthermore, a Lyapunov-based index is used to evaluate the robustness properties of the closed loop. In order to obtain a reduced order controller, the method of balanced truncation is used. The suboptimal H/spl infin/ controllers are output feedback controllers. These controllers posses superior robustness as compared to conventional PSS and optimal H/spl infin/ controllers.