Abstract
Abstract. Impact fatigue caused by collision with rain droplets, hail stones and other airborne particles, also known as leading-edge erosion, is a severe problem for wind turbine blades. Each impact on the leading edge adds an increment to the accumulated damage in the material. After a number of impacts the leading-edge material will crack. This paper presents and supports the hypothesis that the vast majority of the damage accumulated in the leading edge is imposed at extreme precipitation condition events, which occur during a very small fraction of the turbine's operation life. By reducing the tip speed of the blades during these events, the service life of the leading edges significantly increases from a few years to the full expected lifetime of the wind turbine. This life extension may cost a negligible reduction in annual energy production (AEP) in the worst case, and in the best case a significant increase in AEP will be achieved.
Highlights
Leading-edge erosion (LEE) is a severe problem for the wind energy sector today (Keegan et al, 2013; Slot et al, 2015)
The objective of this paper is to present and support the hypothesis on the mitigation of leading-edge erosion by control of wind turbines during high-intensity rain events
Based on the assumed rain climate and the five erosion control strategies (Tables 4 to 8), the aerodynamic modelling and the cost of energy, inspection and repair, the overall loss of income due to leading-edge erosion and its mitigation are calculated for the different erosion control strategies
Summary
Leading-edge erosion (LEE) is a severe problem for the wind energy sector today (Keegan et al, 2013; Slot et al, 2015). Recently 273 blades with less than 7 years in operation were refurbished at an offshore wind farm in the North Sea. Some of the blades were even removed and taken ashore for the repair of damages due to LEE (Wittrup, 2015). During the review phase of this paper, it has been revealed that several blades of one hundred and eleven 3.6 MW turbines at the Anholt offshore wind farm will be dismantled and brought ashore for the repair of leading-edge erosion damage less than 5 years after the wind farm was inaugurated. Similar repair campaigns are foreseen for the London array with 175 similar turbines and other UK offshore wind farms (Renews, 2018a, b; OffshoreWind.Biz, 2018)
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