The effect of site-specific wind conditions and individual pitch control on wear of blade bearings

Abstract

Abstract. The characteristics of a pitch controller determine how the wind turbine reacts to different wind conditions. Control strategies like individual pitch control are known for their ability to reduce the amplitudes of load cycles of the structures of the wind turbine while influencing the operation conditions of the blade bearings in a challenging way. However, the control strategy is not the only influencing factor with respect to failure modes of blade bearings like wear and raceway fatigue. The site-specific and stochastic wind conditions can cause wear-critical operating conditions, which are usually not reflected in the rather short time frames of aeroelastic simulations. This work analyses exemplary wind and operating conditions of one specific site regarding their influence on wear in blade bearings. It is based on measured wind conditions and the modeled behavior of the individual pitch-controlled IWT-7.5-164 reference wind turbine with respect to its pitch activity. The simulation data are used to determine the longest period of uninterrupted wear-critical operation and create a test program based on it for scaled and real-size blade bearings. Experimental results based on this test program show that wear-critical operation conditions can occur during normal operation of a wind turbine and cause mild wear damage to the bearing raceways.

Review of Wind Power Bearing Wear Analysis and Intelligent Lubrication Method Research

“…Due to operation in harsh environments, the uncertainty of wind direction, wind speed, and the rotation of the hub will bring different axial force, radial force, and tilting moments to the pitch bearing [42]. These factors can accelerate the wear of the pitch bearings, which can affect the smooth rotation of the blades and reduce the power generation efficiency of the entire wind turbine system [43,44]. Wind turbine pitch-bearing wear is mainly manifested in two forms: surface wear and internal wear.…”

Instrumentation for the Investigation of Pitch Bearing Design and Reliability

“…Significant work has been done to investigate the fatigue lives and wear characteristics of pitch bearings on ground-based test rigs (Handreck et al 2015;Becker et al 2017;Grebe et al 2018;He et al 2018;Liu et al 2018;Schwack, Prigge, and Poll 2018;Fischer and Mönnig 2019;Schwack et al 2020Schwack et al , 2021Song and Karikari-Boateng 2021;Bartschat, Behnke, and Stammler 2023;Becker et al 2023;Behnke and Schleich 2023;Graßmann, Schleich, and Stammler 2023;de la Presilla et al 2023). NREL has also recently begun a research program related to studying pitch bearing reliability, as its importance grows for wind turbines.…”