Decentralised nonlinear variable structure control for AC-DC power system

The authors present a new approach to the decentralised nonlinear VSS control for the transient stability of AC-DC power system. Based on the characteristics of the system and the sufficient condition for the existence of the equivalent control of VSS, the decentralised nonlinear sliding surface is chosen so that the reduced order dynamics exhibits a linear behaviour in a sliding mode. The controller is decentralized and its parameters are easily chosen. The influence of every parameter of the controller on the system performance is analysed in detail. The design method, which is based on the basic concept of VSS and is formulated by using an algebra method, is easier to understand and simpler than the nonlinear control method by using geometric theory