Multi-index Nonlinear coordinated control for TCSC and hydro-turbine generator excitation and governor

An improved nonlinear control strategy is proposed in this paper. The main improvement made by the authors to the traditional nonlinear control which is based on the differential geometric theory is that an appropriate output function is selected to introduce a nonlinear transformation. Although, such transformation can only partially linearize the nonlinear system, it does provide a way to realize a multi-index control for high order nonlinear systems. Furthermore, with appropriate treatments for the remained part of the nonlinear system after partial linearization, satisfactory performance of the controller can be obtained. The proposed nonlinear control scheme was used to design a coordinated control for a TCSC and a hydro-turbine generator including the excitation and the governor. As the controlled system is a high order nonlinear system characterized with a non-minimum phase problem, design a coordinated control for such system is quite difficult by the conventional nonlinear control theory. Simulation results show very encouraging result. Both dynamic characteristics and the control accuracy of the controlled system are considerably improved.