Reduction of wind turbine gearbox damage risk due to electrical faults via component design optimization

Abstract

Over the lifetime of a wind turbine (WT) it is likely that several electrical faults occur. Electrical faults may induce significant electromagnetic generator torque excitations. The torque excitations are transferred to the gearbox components and lead to dynamic load changes as well as changes in the speed of rotation. Dynamic load changes in combination with changing rotational speeds might lead to gearbox component damage. Gearbox component damage is the main driver for WT downtime due to the high time to repair the fault. Especially the components of the high-speed stage (HSS) are prone to failure. This paper presents a method for introducing gearbox component design optimizations in order to reduce the damage risk during electrical faults. Via profile shift the HSS safety against scuffing cannot be further increased compared to the reference. The HSS safety against micropitting can be increased via profile shift by max. 41% and the safety against tooth flank fracture on the HSS by max. 3% compared to the reference. Via profile modification the HSS safety against scuffing can be increased by max. 14%, the HSS safety against micropitting by max. 8% and the safety against tooth flank fracture on the HSS by max. 8% compared to the reference. Via roller profile optimization the smearing risk on the HSS cylindrical roller bearing can be reduced by max. 3% compared to the reference. Thus, on the basis of two exemplarily analyzed electrical faults, this paper shows that gearbox component design optimizations can significantly reduce the gearbox damage risk during electrical faults.