Lateral Tower Load Mitigation by Generator Torque Control

This paper concerns the increased lateral tower vibrations, caused by lateral water wave loading. The lateral tower vibration mode of wind turbines are generally low aerodynamic damped, therefor load input from e.g. waves orthogonal to the the wind direction will cause large fatigue load contribution to the tower and foundation. In this work a simple tower and drive train model is used to evaluate the potential of using generator torque to reduce lateral tower vibrations and to design a generator torque controller. One control design is tested in nonlinear aeroelastic simulations showing 40 % tower fatigue load reduction with a 10 % drive train load increase.