Control of variable-speed wind turbines: standard and adaptive techniques for maximizing energy capture

This article considers an adaptive control scheme previously developed for region 2 control of a variable speed wind turbine. In this paper, the question of theoretical stability of the torque controller is addressed, showing that the rotor speed is asymptotically stable under the torque control law in the constant wind speed input case and L₂ stable with respect to time-varying wind input. Further, a method is derived for selecting γ_ΔM in the gain adaptation law to guarantee convergence of the adaptive gain M to its optimal value M*.