An optimal power‐decoupling control strategy between torque and pitch controllers for variable‐speed pitch‐regulated wind turbines

Summary As both pitch controller and torque controller are intended to maintain generator speeds close to a set point near the rated wind speed, it is necessary to implement a decoupling strategy between these two controllers in variable‐speed pitch‐regulated wind turbines. A basic power‐decoupling control strategy typically utilizes a power comparator as the switch logic for torque and pitch controllers. Because of the high inertia of the rotor, the turbine could easily suffer serious overshoot of the generator speed and may even deteriorate under extreme mechanical load in the case of gusts. On the basis of the idea of compromising between mechanical load and wind‐energy capture, an optimal power‐decoupling control strategy is proposed based mainly on a pitch‐power proportion integration (PI) loop. Simulations and field testing show that the proposed strategy can effectively reduce mechanical load by allowing pitch action to take place in advance, before rated power is reached under gust conditions.