Structured H-Infinity Controller for an Uncertain Deregulated Power System

A deregulated power system is considered to be a highly complex uncertain system due to the presence of multiple bilateral transactions. Load frequency control in such a system hence assumes significance because of the challenging nature of operation and therefore use of robust controllers is imperative. Conventional robust controller designs give higher order controllers and hence restricts its application in the industry. But the alternative is to use structured H-infinity controllers, which give sufficiently lower-order controllers and can be used in system with nonlinearities. In this paper, structured H-infinity controller has been designed for a deregulated power system considering the effect of nonlinearities like generation rate constraint, governor deadband, and time delay associated with communication network in the system from practical point of view. These physical constraints demand an electrical energy storage system. Hence, load frequency control is accomplished with a structured H-infinity controller supplemented with redox flow battery in each area of a two-area deregulated power system consisting of GENCOs of reheat thermal type.