Individual Blade Pitch Control for Extended Fatigue Lifetime of Multi-Megawatt Wind Turbines

A novel experimental study on the use of individual pitch control to extend the fatigue life of wind turbines is conducted. The experiment is accomplished using a sub-scale model of a multi-megawatt turbine in both upwind and downwind configurations in a water towing tank. It is shown that individual pitch control based on a sinusoidal pitching scheme that is locked to the phase of the rotor rotation can mitigate unsteady loads caused by the velocity variation that is induced by the effect of rotor tilt and therefore extends the fatigue lifetime of blades. A positive pitching amplitude in the case of upwind configuration and a negative pitching amplitude in the case of downwind configuration eliminate the cumulative damage fractions due to the velocity variation.