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Improving wind turbine drivetrain bearing reliability through pre-misalignment.

Whittle, M.W.G. and Trevelyan, J and Shin, W. and Tavner, P.J. (2013) 'Improving wind turbine drivetrain bearing reliability through pre-misalignment.', Wind energy., 17 (8). pp. 1217-1230.


Improving the reliability of wind turbines (WT) is an essential component in the bid to minimize the cost of energy, especially for offshore wind because of the difficulties associated with access for maintenance. Numerous studies have shown that WT gearbox and generator failure rates are unacceptably high, particularly given the long downtime incurred per failure. There is evidence that bearing failures of the gearbox high-speed stage (HSS) and generator account for a significant proportion of these failures. However, the root causes of these failure data are not known, and there is therefore a need for fundamental computational studies to support the valuable ‘top down’ reliability analyses. In this paper, a real (proprietary) 2 MW geared WT was modelled to compute the gearbox–generator misalignment and predict the impact of this misalignment upon the gearbox HSS and generator bearings. At rated torque, misalignment between the gearbox and generator of 8500 µm was seen. For the 2 MW WT analysed, the computational data show that the L10 fatigue lives of the gearbox HSS bearings were not significantly affected by this misalignment but that the L10 fatigue lives of the generator bearings, particularly the drive-end bearing, could be significantly reduced. It is proposed to apply a nominal offset to the generator to reduce the misalignment under operation, thereby reducing the loading on the gearbox HSS and generator bearings. The value of performing integrated system analyses has been demonstrated, and a robust methodology has been outlined.

Item Type:Article
Keywords:Wind turbine, Misalignment, Gearbox, Generator, Bearings, Fatigue, Reliability, Availability.
Full text:(AM) Accepted Manuscript
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Publisher statement:This is the peer reviewed version of the following article: Whittle, M., Trevelyan, J., Shin, W. and Tavner, P. (2013), Improving wind turbine drivetrain bearing reliability through pre-misalignment. Wind Energy, 17 (8): 1217–1230 which has been published in final form at This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.
Date accepted:No date available
Date deposited:22 May 2014
Date of first online publication:August 2013
Date first made open access:No date available

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