Investigation of blade bearing loads during individual pitch control operation

Blade bearings in modern wind turbines are typically rolling bearings that connect the rotor blades to the hub, enabling blade pitch adjustment for power and load control. The implementation of Individual Pitch Control (IPC) reduces asymmetric mechanical loads but increases the frequency of loading on the blade bearings. Within the Flamingo project, a measurement system was installed on a 5.3 MW wind turbine to investigate blade bearing deformation under various operational conditions. Fiber optic strain sensors were positioned at seven locations in each blade bearing, complemented by additional load measurements on the blades, tower, and main shaft. The analysis reveals that both changes in rotor speed and wind speed significantly affect blade bearing deformation. While IPC operation tends to result in higher loads, the differences between IPC and non-IPC modes are not consistent and are strongly influenced by other operational parameters. The findings provide valuable insights into the loading and behaviour of blade bearings under real operating conditions, highlighting that beyond other factors IPC also play a significant role in bearing loads.