A Disturbance Observer Based Sliding Mode Control for Variable Speed Wind Turbine.

This paper shows the effectiveness of disturbance observer (DO) based sliding mode control (SMC) scheme as compared to traditional SMC. Both the methods are simulated for variable speed wind turbine (VSWT) to ensure asymptotic tracking of rotor speed even in the presence of disturbances. Two mass model of VSWT is derived which includes the damping effect of the rotor's blade and generator. The stiffness and damping effect of low-speed shaft are also taken into account while modelling the system. The dynamic model of VSWT contains both matched and mismatched uncertainties. Traditional SMC can only attenuate the effect of match uncertainties. The DO-based SMC overcomes the drawback of traditional SMC by attenuating mismatch uncertainties. In the proposed approach, a sliding manifold is chosen based on the estimation of an uncertain parameter (aerodynamic torque), which drives the system's states to equilibrium point in a finite time. [ABSTRACT FROM AUTHOR]