Design of a Robust State Feedback Controller for a STATCOM Using a Zero Set Concept

A static synchronous compensator (STATCOM) is one of the fundamental flexible ac transmission system devices that can be used for voltage regulation and dynamic voltage control. In this paper, a new approach to the problem of the STATCOM state feedback design is presented. The proposed solution technique is based on a zero set concept. It allows one to calculate a complete set of the admissible feedback gains that place closed-loop poles into a prespecified region in the complex plane under parametric uncertainties in the plant model. These uncertainties represent load pattern variations and topological changes due to line tripping. Computational examples show that by using the design technique based on the zero set concept, it is possible to derive the state feedback controllers with better robustness properties than those achieved using the approaches utilizing linear matrix inequalities.