Nonlinear robust control to maximize energy capture in a variable speed wind turbine

The emergence of wind turbine systems for electric power generation can help satisfy the growing global demand. To maximize wind energy captured in variable speed wind turbines at low to medium wind speeds, a robust control strategy is presented. The proposed strategy simultaneously controls the blade pitch and tip speed ratio, via the rotor angular speed, to an optimum point at which the efficiency constant (or power coefficient) is maximum. The control method allows for aerodynamic rotor power maximization without the restrictions of exact wind turbine model knowledge. A series of numerical results show that the wind turbine can be controlled to achieve maximum energy capture.