Developing a systematic approach to the analysis of time‐varying main bearing loads for wind turbines

This paper considers the time‐varying loads experienced by wind turbine main bearings. Radial load trajectories based on simulated data indicate that ‘looped’ structures, in the form of repeating changes in radial load magnitudes and directions that form elliptical patterns, are present, which have not been described before in the literature. In order to allow these identified structures to be described and studied, an automated method for identification and parameterisation of these loops is presented, along with preliminary results from applications on simulated data. In order to assess the relative importance and potential impacts of these identified structures on bearing rollers, an internal load model for double‐row spherical roller bearings is also developed. Results indicate that identified loops in radial main bearing applied loads lead to significant fluctuations in bearing roller loads, even within normally unloaded regions. These findings motivate further study with respect to the identified load structures and their impacts on wind turbine main bearing internal loading and failures. The methods developed in this paper provide the basis for a systematic approach and necessary tools for this future work.