Preventing Tower Resonance Induced by Thrust Variations on a Large 10MW Wind Turbine

Abstract

A simulation model based on a 10MW wind turbine is developed to test the performance of a speed exclusion zone algorithm with the purpose of preventing tower resonance. The model includes rotor aerodynamics, drive-train and generator dynamics, and finite element formulation of the tower and substructure. A rotor speed controller is also implemented. The algorithm is able to reduce tower vibration at the expense of power output. To properly test the algorithm a wind model for simulation of thrust variations on a wind turbine is developed. The wind model accounts for wind shear, tower shadow, turbulence and rotor sampling. Wind shear is shown to have a depleting effect on the mean thrust and tower shadow is shown to cause significant thrust variations oscillating with the blade passing frequency. Turbulent wind fluctuation cause low-frequency thrust variations in addition to thrust oscillating with the blade passing frequency.