In this paper, based on the bounds of parametric uncertainties the necessary and sufficient conditions for the existence of a sliging regime, and the occurrence of hitting in a variable structure system, are presented. A new variable structure control algorithm is proposed to solve the load-frequency control problem for an interconnected hydrothermal power system. The simulation results demonstrate that using the proposed controller the transient responses of the system are greatly improved and the dynamic performance of the system is better than that of the conventional control scheme. Furthermore, the proposed approach is robust to the plant parameters' variations, and the characterization of the system is as good as the full state switching when the reducing switching scheme is adopted.
International jouernal of system science 26(3), pp.467-480