Maximum Wind Energy Extraction for Variable Speed Wind Turbines With Slow Dynamic Behavior

Currently, the maximization of wind energy extraction for variable speed wind turbines (VSWT) is usually transformed into the maximum power point tracking (MPPT), i.e., the rotor speed is continuously regulated to follow the optimal rotor speed as a function of wind speed. However, it has been recognized that the increasing rotor inertia and the high fluctuation of wind speed result in the turbines' being unable to instantly track the optimal rotor speed and tracking losses. This indicates that maximizing wind energy extraction based on MPPT is not suitable for large-inertia VSWTs under turbulence. Moreover, it is revealed and demonstrated in this letter that a conservative speed reference matching up with the slow dynamic behavior of VSWTs can effectively improve wind energy production, which provides a new approach for maximizing wind energy extraction of VSWTs under turbulence.