Wind turbine main‐bearing loading and wind field characteristics

Abstract

This paper investigates the relationship between wind turbine main‐bearing loads and the characteristics of the incident wind field in which the wind turbine is operating. For a 2‐MW wind turbine model, fully aeroelastic multibody simulations are performed in 3D turbulent wind fields across the wind turbine's operational envelope. Hub loads are extracted and then injected into simplified drivetrain models of three types of main‐bearing configuration. The main‐bearing reaction loads and load ratios from the simplified model are presented and analysed. Results indicate that there is a strong link between wind field characteristics and the loading experienced by the main bearing(s), with the different bearing configurations displaying very different loading behaviours. Main‐bearing failure rates determined from operational data for two drivetrain configurations are also presented.

A review of wind turbine main bearings: design, operation, modelling, damage mechanisms and fault detection

“…Hub loadings taken from aeroelastic code are used as inputs to models which represent three-and fourpoint mount systems in order to compare the loads seen by each. The results of this work indicate that radial loads seen by four-point mount systems are generally higher than for the three-point system, but they also saw a corresponding reduction in axial-to-radial load ratios, a quantity for which high values have been associated with potentially damaging events such as unseating of rollers (Hart et al, 2019). Given the reported higher instances of failures in three-point systems in this same work, it is suggested that specific loading combinations (in terms of axial and radial loads) rather than just individual load magnitudes may be important to understanding failures.…”

“…In Hart et al (2019) the loading experienced by WTMBs is investigated using simple beam-support representations of the drivetrain 5 . Hub loadings taken from aeroelastic code are used as inputs to models which represent three-and fourpoint mount systems in order to compare the loads seen by each.…”

“…The motivation for this current review is the observation that the wind industry has identified wind turbine mainbearing (WTMB) failures as being a critical issue in terms of increasing wind turbine (WT) reliability and availability. Recently reported figures show that main-bearing (MB) failure rates (over a 20-year lifetime) can be as high as 30 % (Hart et al, 2019). Additionally, industry experts at the 2016 WT Drivetrain Reliability Collaborative Workshop (Keller et al, 2016) consistently identified the MB as being the second most important reliability challenge after WT gearboxes in a diverse range of areas, including MB failure modes, standards and certification, modelling and measurement of internal axial motion, condition monitoring techniques, and lubrication.…”

“…This might indicate that MB failures are becoming more of a problem as WTs increase in size; however, there is currently no openly available data with which to test such a hypothesis. As suggested in Hart et al (2019), there therefore seems to be a significant MB knowledge gap which includes failure data, modelling, measurements and design standards. This is in stark contrast to the hundreds of papers in the literature which consider all aspects of WT gearboxes and generators.…”

Constructing Fast and Representative Analytical Models of Wind Turbine Main-Bearings

“…As part of analyses which try to understand the loading conditions of MBs in wind turbines (in order to better understand their operational conditions and load characteristsics), detailed model-based investigations are required. Work of this type exists in the literature (Hart et al, 2019b) in which analytical models are used to consider MB loading. This paper considers the validity of simplified analytical drivetrain representations of the type used in these load studies by comparisons with higher fidelity 3D finite element models.…”