Hybrid control for wide-area power systems based on hybrid system theory

The article focuses on a new two-level hierarchical hybrid control which contains an upper layer discrete supervisory strategy and lower layer continuous decentralised coordinated control based on hybrid system theory for wide-area power system overall stability enhancement. The discrete supervisory strategies are constituted based on an information fusion technique by using wide-area measurements (WAMs) in order to supervise and switch the control actions into apposite operation mode following a large disturbance. The continuous control is designed in the form of a local state feedback decentralised controller for each generator helped by a coordinated controller, and the coordinated controller is proposed to apply the remote signals from the WAM systems for improving dynamic performance. However, unavoidable communication time delays are involved before the remote signals are received at the coordinated controller. Taking account of the multiply delays, the authors develop a delay-dependent H∞ robust control technique based on multiple Lyapunov stability theory. Some new stability criteria for hybrid control are derived in terms of linear matrix inequality. The so-called hybrid control is demonstrated through simulation examples to achieve the best overall performance following a large disturbance.