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Leading edge erosion of wind turbines: Effect of solid airborne particles, rain on operational wind farms

Hamish Law and Vasileios Koutsos|May 19, 2020
ErosionStructural Failure

This important paper reveals the extent to which erosion of the leading edge of a wind turbine blade from rain is resulting in reductions of electricity output. The study found that taping the blades to address the problem further contributes to the loss of annual performance. The authors warn that additional studies are needed to assess the impact of solid particles including salt from offshore sites on blades. The conclude that "[t]his will be vital in enabling developers to compute more accurate financial forecasts of the lifetime performance of their site, particularly in an era of declining subsidies." The abstract and conclusion of the paper are provided below. The full report can be downloaded from the document links on this page.


Abstract

Leading edge erosion (LEE) affects almost all wind turbines, reducing their annual energy production and lifetime profitability. This study presents results of an investigation into 18 operational wind farms to assess the validity of the current literature consensus surrounding LEE. Much of the historical research focuses on rain erosion, implying that this is the predominant causal factor. However, this study showed that the impact of excessive airborne particles from seawater aerosols or from adverse local environments such as nearby quarries greatly increases the levels of LEE.

Current testing of leading edge protection coatings or tapes is based on a rain erosion resistivity test, which does little to prove its ability to withstand solid particle erosion and may drive coating design in the wrong direction. Furthermore, it was shown that there is little correlation between test results and actual field performance. A method of monitoring the expected level of erosion on an operational wind turbine due to rain erosion is also presented.

Finally, the energy losses associated with LEE on an operational wind farm are examined, with the average annual energy production dropping by 1.8% due to medium levels of erosion, with the worst affected turbine experiencing losses of 4.9%.

Conclusion

Analysis of the sites that were subjected to excessive airborne particles from quarries or sea-salt aerosols revealed vastly more severe levels of LEE. The extent to which an adverse environment can accelerate LEE has been grossly unreported in current literature to date. The dynamic modelling approach appeared to be capable of monitoring the onset and severity of rain LEE with the caveat that further testing be conducted beyond 2 years of operation. This study also revealed the inadequacy of current LEP coating testing standards. The Springer method of correlating rain erosion test results to actual field performance failed dramatically, most likely due to the incongruency between testing and field conditions. Furthermore, rain erosion testing does not account for erosion by solid airborne particles, which has been shown to greatly accelerate LEE. Therefore, it is imperative that a new testing standard is developed for LEP coatings that accounts for erosion by solid airborne particles and facilitates greater correlation between test results and field performance.The quantification of energy losses associated with LEE revealed that an average AEP loss of 1.8% was found on a site with medium levels of LEE, with the worst affected turbine experiencing losses of 4.9%. Although these results were largely congruent with the literature consensus, further such analysis using LIDAR technologies or individual met masts must be conducted to establish greater knowledge of the associated AEP losses with actual field turbines. This will be vital in enabling developers to compute more accurate financial forecasts of the lifetime performance of their site, particularly in an era of declining subsidies.

Attachments

Wind Energy 2020 Law Leading Edge Erosion Of Wind Turbines Effect Of Solid Airborne Particles And Rain On Compressed

November 25, 2022


Source:https://onlinelibrary.wiley.c…

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