Research ArticleRobust fractional order sliding mode control of doubly-fed induction generator (DFIG)-based wind turbines

•A novel robust fractional-order sliding mode (FOSM) controller for maximum power point tracking control of DFIG-based wind energy conversion system.•Fraction order surface is used to improve performance.•Uncertainty is estimated with a fractional order uncertainty estimator.•Chattering-free sliding mode control is achieved.•No knowledge of the uncertainties and disturbances or their bounds is assumed.

Wind power plants have nonlinear dynamics and contain many uncertainties such as unknown nonlinear disturbances and parameter uncertainties. Thus, it is a difficult task to design a robust reliable controller for this system. This paper proposes a novel robust fractional-order sliding mode (FOSM) controller for maximum power point tracking (MPPT) control of doubly fed induction generator (DFIG)-based wind energy conversion system. In order to enhance the robustness of the control system, uncertainties and disturbances are estimated using a fractional order uncertainty estimator. In the proposed method a continuous control strategy is developed to achieve the chattering free fractional order sliding-mode control, and also no knowledge of the uncertainties and disturbances or their bound is assumed. The boundedness and convergence properties of the closed-loop signals are proven using Lyapunov׳s stability theory. Simulation results in the presence of various uncertainties were carried out to evaluate the effectiveness and robustness of the proposed control scheme.