It is well known that wind turbine blades are fatigue critical, with much literature and methodologies available for assessing fatigue loading of large wind turbine blades. Little research effort has been directed at assessing the fatigue life of small wind turbines which operate at higher rotational speeds and are subject to highly unsteady aerodynamic loading. In this paper the simplified load model proposed in IEC 61400.2 is used to determine the fatigue life of a small 5 kW wind turbine blade. This estimated life is compared to that determined from both measured operational data and aeroelastic simulations. Fatigue life was estimated by the standard at 0.09 years, compared to 9.18 years from field measurements and 3.26 years found via aeroelastic simulations. All methods fell below the 20 year design life, with the standard over-conservative by a factor of 102 and 36 for measurements and simulations respectively. To the best of the authors' knowledge these three fatigue methods specified in the standard have not been quantitatively compared and assessed for small wind turbines. Results are of importance to small wind turbine developers as they seek best practice for determining blade fatigue life. Shortcomings of the IEC methodology are detailed and discussed.

中文翻译：

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评估小型风力涡轮机叶片的 IEC 简化疲劳载荷方程：有多简单太简单？

众所周知，风力涡轮机叶片对疲劳至关重要，有许多文献和方法可用于评估大型风力涡轮机叶片的疲劳载荷。很少有研究致力于评估以较高转速运行并承受高度不稳定空气动力载荷的小型风力涡轮机的疲劳寿命。在本文中，IEC 61400.2 中提出的简化载荷模型用于确定小型 5 kW 风力涡轮机叶片的疲劳寿命。将该估计寿命与根据测量的操作数据和气动弹性模拟确定的寿命进行比较。标准估计的疲劳寿命为 0.09 年，而现场测量为 9.18 年，气动弹性模拟为 3.26 年。所有方法都低于 20 年的设计寿命，对于测量和模拟，标准过度保守分别为 102 和 36 倍。据作者所知，标准中规定的这三种疲劳方法尚未针对小型风力涡轮机进行定量比较和评估。结果对于小型风力涡轮机开发商来说很重要，因为他们正在寻求确定叶片疲劳寿命的最佳实践。详细讨论了 IEC 方法的缺点。