Robust Adaptive Prescribed-Time Tracking Control for Variable-Speed Wind Turbines Subject to Multiple Uncertainties

To improve the annual generation capacity and assure the operational reliability for variable-speed wind turbines (VSWTs), this article solves a challenging issue in tracking the optimal tip speed ratio within the prescribed instant of time for extracting the maximum power. The obstacle is how to make the tracking error kept within predetermined time-varying constraint on the whole time-horizon under the impact of uncertainties and external disturbances and keep the angular discrepancy between the low-speed shaft and the high-speed shaft bounded. Utilizing a time-varying constraint function constructed with tracking accuracy and the prescribed-time, we devise a continuous robust adaptive controller by incorporating adaptive laws of unknown parameters with a composite function linked to the boundary constraints. Exceeding prior tracking performance of VSWTs, the proposed scheme is able to guide the tracking error into a predefined range within a prescribed instant of time in the presence of uncertainties and disturbances while guaranteeing the global boundedness of the signals in the closed-loop system. Finally, experimental verification is conducted to showcase the superiority/practicability of the constructed approach.