Wear test programs for roller-type pitch bearings of wind turbines

Abstract

Pitch bearings are critical for the safe and efficient operation of wind turbines. They connect the rotor blades to the rotor hub and allow for pitching movements that control loads and rotor speeds. While four-point-contact ball bearings have been dominant in the past, three-row roller bearings are increasingly used in current designs due to their higher load capacity at the same diameter. Wear of the raceways is one of the possible damage mechanisms in pitch bearings. As roller bearings differ significantly from previous designs and because the operational conditions of wind turbines differ from other industrial applications, it is a reasonable de-risking exercise to undergo wear tests prior to the commissioning of such bearings. This study outlines a process for developing a wear test program based on aero-elastic simulation data and wind speed measurements. The process is then applied to an example roller bearing. The final program covers both standstill conditions and pitch cycles. The first is the main addition to former approaches. With existing test rigs and a reasonable budget and timeline, the program can be executed.