Robust Decentralized LFC Design in a Restructured Power System

In this paper, a new approach based on µ-synthesis technique is presented for the robust decentralized load frequency controller design of a restructured multi area power under the possible contracts. In each control area, the connections between this area and the rest of the system and the effects of possible contracts are treated as a set of new disturbance signals to achieve decentralization. It is shown that, subject to a condition based on the structured singular values and H infinity norm, each local area load frequency controller can be designed independently. The stability condition for the overall system can be stated as to achieve a sufficient interaction margin and a sufficient gain and phase margin defined in classical feedback theory during each independent design. The proposed method is tested on a four-area power system with the possible contracts and compared with the PI controller for a wide range of operating conditions and load changes. The resulting controllers are shown to minimize the effects of load disturbances and maintain robust performance in the presence of specified uncertainties and system nonlinearities.