Adaptive sliding mode control scheme for a wave power generation plant

Robust control algorithms may improve the efficiency of wave power conversion systems since they present intrinsic nonlinear dynamics and the system uncertainties. Sometimes, the generators that can operate al variable speed (e.g. double feed induction generator) are used at wave power generation plants, since they may improve the system efficiency to generate power when compared to fixed speed generators. The main reason is that this generators with variable speed may adapt the speed of the turbine in order to maintain the optimun flow coefficient value which improving its efficiency. This paper proposes a sliding mode controller for wave power plants based on a double feed induction generator. Also, the presented robust control scheme introduces an adaptive sliding gain that avoids calculating the upper bound for the uncertainties of the system, facilitating its application. The stability of the proposed control scheme is analyzed by means of the Lyapunov stability theory. Finally, the proposed control scheme is validated through some simulation examples.