Numerical Procedure for Design Optimization of Wind Turbine Drivetrain Using Multibody Gear Dynamics Simulation Considering Wind Load Uncertainty

An accurate prediction of the service life of wind turbine drivetrains is crucial to ensure safe and reliable operation. In particular, gear teeth of the wind turbine multi-stage drivetrain experience severe cyclic rolling contact resulting from highly variable wind loads which are stochastic in nature. Thus, the failure rate of the gearbox is reported to be higher than other wind turbine components. Despite many studies on gear contact and failure analysis of wind turbine drivetrains, limited studies have been carried out regarding gear design optimization considering wind load uncertainty. For this reason, in this study, an integrated multibody gear dynamics simulation procedure for design optimization of the wind turbine drivetrain considering the wide spatiotemporal wind load uncertainty is developed. To this end, the wind load uncertainty model using the joint probability density function of the ten-minute mean wind speed and turbulence intensity, rotor blade aerodynamics, drivetrain dynamics considering the detailed gear tooth contact geometry including the profile modification, and probabilistic contact fatigue failure model are integrated for use in the gear tooth design optimization of wind turbine drivetrains to ensure the expected design life. Several numerical examples are presented to demonstrate the numerical procedure developed in this study.