Robust load-frequency controller design for interconnected power systems with circular pole constraints via LMI approach

The aim of this paper is to investigate the design problem of robust load-frequency controller (both state feedback and output feedback cases) for interconnected power systems with circular pole constraints. Here, the uncertainty is assumed to be norm-bound and appears in both the system and input matrices. The necessary and sufficient conditions for the existence of desired controllers are derived in terms of a linear matrix inequality (LMI). Additionally, it is shown that this existence condition is equivalent to the feasibility of a certain matrix inequality which is jointly convex in all variables, and a set of desired controller is characterized using the feasible solution to this LMI. Finally, the application of the proposed robust control method is not only considered through simulation studies of two-area power systems model, but also compared with the recent work of [Wang et al. (1993)] and [Ray et al. (1999)] and found to be very effective.