An improved MPPT control strategy based on adaptive optimization of speed reference

In order to achieve the maximum power extraction below its rated value, wind turbine is generally controlled by maximum power point tracking (MPPT) strategies. However, due to the large inertia of wind turbines, it is difficult to adjust the rotor speed according to the highly fluctuant wind speed accurately and quickly. Consequently, the efficiency of wind energy extraction will not reach its theoretical maximum value. To address this problem, a more conservative speed reference that is suitable for the sluggish behavior of wind turbines was proposed to improve the MPPT performance. In this paper, a first-order digital filter is adopted to smooth the optimal speed. It is illustrated that a single-peak curve satisfies the statistical relation between the filter parameter and the average wind energy capture efficiency as turbulence condition varies. On this basis, a control strategy based on an adaptive algorithm is proposed to optimize the speed reference. Finally, it is verified through FAST (Fatigue, Aerodynamics, Structures, and Turbulence) simulation that the proposed method can increase wind energy production.