Response Analysis of Parked Spar-Type Wind Turbine Considering Blade-Pitch Mechanism Fault

摘要

Floating offshore wind turbines experience fault conditions. For a parked wind turbine, if the pitch mechanism fails, the blades cannot be feathered to the maximum pitch set point-the blades are seized. Three parked scenarios are considered: fault with 1 seized blade, fault with 3 seized blades, and normal condition. The responses of a spar-type wind turbine are investigated under turbulent wind and irregular wave conditions. However, only the steady-state (and not the transient) response in the fault condition is estimated. In normal parked conditions, the platform-yaw is sensitive to the blade azimuth while surge and pitch are not. The blade azimuth plays a key role in the roll and yaw motion responses in the parked conditions with 1 seized blade. Fault cases under 1-y environmental conditions are compared to normal cases under 50-y environmental conditions. A fault with 1 seized blade often leads to large roll resonance and yaw motion responses with the extremes exceeding the 50-y reference values by more than 16%. The extreme main-shaft bending moments are more than twice the 50-y reference values. Fault cases with 3 seized blades cause an average rise of 38% and 23% for surge and pitch motion extremes, and more than 10% of the tower-bottom bending moments and blade-root bending moments compared to the 50-y reference of the normal operating case.