Fatigue damage is one of the governing factors for the design of offshore wind turbines. However, the full fatigue assessment is a time-consuming task. During the design process, the site-specific environmental parameters are usually condensed by a lumping process to reduce the computational effort. Preservation of fatigue damage during lumping requires an accurate consideration of the met-ocean climate and the dynamic response of the structure. Two lumping methods (time-domain and frequency-domain) have been evaluated for a monopile-based 10 MW offshore wind turbine, both based on damage-equivalent contour lines. Fatigue damage from lumped load cases was compared to full long-term fatigue assessment. The lumping methods had an accuracy of 94–98% for the total long-term fatigue damage and 90% for individual wind speed classes, for aligned wind and waves. Fatigue damage was preserved with the same accuracy levels for the whole support structure. A significant reduction of computational time (93%) was achieved compared to a full long-term fatigue assessment. For the cases with 30° and 60° wind-wave misalignment, there was a mean underestimation of approximately 10%. Variations in penetration depth did not affect the selection of the lumped sea-state parameters. This work presents a straightforward method for the selection of damage-equivalent lumped load cases, which can adequately preserve long-term fatigue damage throughout the support structure, providing considerable reduction of computational effort.

疲劳损伤是设计海上风力发电机的主要因素之一。但是，全面疲劳评估是一项耗时的任务。在设计过程中，通常通过集总过程来压缩特定于站点的环境参数，以减少计算量。保持集总过程中的疲劳损伤需要准确考虑海洋气候和结构的动态响应。对于基于单桩的10 MW海上风力发电机，已经评估了两种集总方法（时域和频域），这两种方法均基于等效损伤轮廓线。将集中负荷情况下的疲劳损伤与全面的长期疲劳评估进行了比较。集总方法对总的长期疲劳损伤的准确度为94–98％，对于单个风速类别的准确度为90％，对准风浪。对于整个支撑结构，疲劳损伤以相同的精度水平得以保留。与完整的长期疲劳评估相比，计算时间显着减少（93％）。对于30°和60°风波未对准的情况，平均低估了大约10％。穿透深度的变化不影响集总海况参数的选择。这项工作提出了一种选择等效损伤集总荷载工况的简单方法，该方法可以充分保留整个支撑结构的长期疲劳损伤，从而大大减少了计算量。与完整的长期疲劳评估相比，计算时间显着减少（93％）。对于30°和60°风波未对准的情况，平均低估了大约10％。穿透深度的变化不影响集总海况参数的选择。这项工作提出了一种选择等效损伤集总荷载工况的简单方法，该方法可以充分保留整个支撑结构的长期疲劳损伤，从而大大减少了计算量。与完整的长期疲劳评估相比，计算时间显着减少（93％）。对于30°和60°风波未对准的情况，平均低估了大约10％。穿透深度的变化不影响集总海况参数的选择。这项工作提出了一种选择等效损伤集总荷载工况的简单方法，该方法可以充分保留整个支撑结构的长期疲劳损伤，从而大大减少了计算量。