Maximizing the performance of variable speed wind turbine with nonlinear output feedback control

In this paper, the problem of designing an output feedback regulation control scheme of variable speed wind energy conversion system with rotor speed measurement is addressed. The controller consists of the combination of a linear control for blade pitch angle with a nonlinear H_∞ torque control and a finite-time convergent Super-Twisting Observer. This strategy does not use the wind velocity and avoid the chattering phenomena. The nonlinear H_∞ torque control take into account the nonlinear dynamic aspect of the wind turbine and the turbulent nature of the wind, also mitigate the effects of external disturbances that occur at the input and output of the system. The controller exhibits better power and speed regulation when compared to classic linear controllers. In order to validate the mathematical model and evaluate the performance of proposed controller, we used the National Renewable Energy Laboratory (NREL) aerolastic wind turbine simulator FAST. Simulation and validation results show that the proposed control strategy is effective in terms of power and speed regulation.