Switching Performance Improvement Based on Model-Predictive Control for Wind Turbine Covering the Whole Wind Speed Range

A wind energy conversion system is mainly operated in a partial-load region and a full-load region. In the partial-load region, the primary objective is to maximize energy conversion efficiency, whereas the main goal is maintaining the output power at the rated level in the full-load region. The two control regions are switched in accordance with prevailing wind speed. However, steep and large changes of generator power, as well as mechanical loads, may be experienced during switching transient, which bring about negative impacts on power system reliability and turbine lifetime. This paper presented an advanced model-predictive control considering switching performance improvement. The proposed method not only achieved the control objectives in both two control regions, but also mitigated uncertain power fluctuations and mechanical loads during control mode switching. This high switching performance benefited from the presented dynamic switching transient process driven by the defined wind speed crossing events. During switching transient, system operating states were transferred along with the proposed dynamic vector. Small-signal analysis was employed to prove the good stability and dynamic performance of the system in switching transients. Simulation and hardware-in-the-loop experimental studies verified the effectiveness of the proposed method.