Analysis of torsional oscillation of the drive train in horizontal-axis wind turbine

The unsteadiness of rotor inflow caused by the atmosphere creates continuous variations of blade loads and rotor torque. Usually these loads are amplified by rotor shaft and gearbox elasticity and inertia. The authors propose here a dynamic multi-body model where the wind turbine includes a rotor, a drive train and an electrical generator. The drive train has a three stage gearbox which contains two high-speed parallel gear stages and a low-speed planetary gear stage. The model consists of 10 bodies and has 8 degrees of freedom taking into account the stiffness of the engaged tooth pairs. In this model the aerodynamic torque is applied as an external load. The calculation permits to obtain natural frequencies, mode shapes, time series of torsional oscillations and amplitude-frequency characteristics for an industrial wind turbine. The results show that transient loads in the gearbox are very high and need special attention.