Design of observer-based decentralized load-frequency controllers for interconnected power systems

A new decentralized load-frequency control scheme for an interconnected power system is presented. In this scheme, the interconnected system is decomposed into several subsystems, where each subsystem consists of a local system and its simplified external equivalent which is the main source of information about the original external system. A linear optimal controller is designed for each subsystem based on the decomposed model. Since the states of the external equivalent model are inaccessible from the local system, a suitable minimal-order observer using only the local system information is designed to estimate them. These controllers along with the observers are implemented in the original system. This method of utilizing the state information of neighbouring areas estimated by an observer for the decentralized load-frequency controller design is the main contribution of the paper. The application of the decentralized load-frequency control scheme is illustrated using a two-area interconnected power system.