Analysis and simulation of a sliding mode controller for mechanical part of a doubly-fed induction generator-based wind turbine

In this study, a sliding mode controller (SMC) is designed to regulate rotor speed, and therefore generated power of a doubly-fed induction generator-based wind turbine. The designed controller is able to compensate for the uncertainty arising from non-linear and un-modelled dynamics, reject wind turbulence disturbance, and effectively keep the rotor speed and produced power close to a nominal value. Since the chattering phenomenon increases the control activities and excites unwanted high-frequency dynamics of a system and even in some cases, causes system instability; therefore, a fixed boundary layer is used to avoid the chattering. The simulation results show the considerable superiority of the designed SMC in comparison with the conventional proportional-integral (PI) controller and the PI controller calculated through optimal control method. Improving dynamic characteristics, reducing the maximum amplitude of oscillations, and increasing the convergence speed of the states are achieved in this research.