Extending standard H∞ controller to H∞ /sliding mode controller with an application to power system stabilisation

A new H,/sliding mode controller under a worst-case scenario is described. The controller is designed to solve the problem associated with unmeasurable state variables in the traditional sliding-mode controller, and to improve the time-domain performance under a worstcase scenario. The control input, derived by Lyapunovʹs second method, keeps the system stable. Proof of closed-loop stability is done by an additional form of a sliding surface and an estimation error.