The effect of torque scheduling on the performance and mechanical loads of a wind turbine

Abstract

The generator torque control loop of a multi-MW wind turbine consists of three operational regions, i.e. a max Cp region, a transient region around the rated rotor speed, and a power regulation region. The performance and mechanical stress on the wind turbine structure are closely related with how the torque schedule is mechanized in the transient and above-rated regions. Using a drive train model, the closed loop dynamic characteristics for different torque schedules were analyzed. It is found that the slope of the torque for the rotor speed in the transient region is the major factor which determines the performance and mechanical loading of the wind turbine. The effect of using a variable torque instead of the fixed rated torque in the above-rated region is also analyzed.