15-MW 浮式風機於颱風下之運動、負載與風浪場特性分析

Abstract

本研究以 15MW 半潛式浮式風力發電機為對象，系統性探討其於台灣海峽實際颱風環境下的動態響應與結構負載特性，並評估關鍵影響因子。首先，整合 2024 年凱米颱風觀測風場與波浪資料，建立具代表性的極端環境條件，並運用 Ansys AQWA 進行浮台水動力分析、TurbSim 生成風場，結合 OpenFAST 完整數值模擬，重現浮式風機於颱風期間不同條件下的運動與受力行為。分析範圍涵蓋浮台六自由度運動響應、塔底彎矩與葉根彎矩等關鍵結構部位之時序變化、統計特性及等效疲勞載重。進一步以隨機森林回歸模型，評估多項環境參數（如風速、波高、風向、波向、風浪夾角、轉子轉速）對浮台運動與結構負載之相對重要性。結果顯示，颱風環境下浮式風機於運轉條件之運動與結構負載變異性皆顯著高於停機條件，塔底與葉根等效疲勞負載平均值分別較停機提升約 76.8% 與 82.5%。隨機森林模型指出，運轉條件下浮台縱搖為主導塔底與葉根彎矩變異之關鍵自由度，而在停機條件下，塔底彎矩主要受縱搖控制，葉根彎矩則以橫搖為主，但縱搖之重要度亦高達 0.87。進一步針對關鍵自由度進行環境因子細部分析，結果顯示風向與風速為影響浮台運動的主要參數，而示性波高與峰值週期之重要度皆低於 0.4，顯示其在本研究涵蓋之颱風情境中影響相對有限。整體成果可為台灣地區浮式離岸風電於極端氣候下之設計、評估及運維策略提供重要參考。

This study investigates the dynamic responses and structural load characteristics of 15 MW floating offshore wind turbine under typhoon conditions in the Taiwan Strait, with particular emphasis on evaluating key influencing factors. Representative extreme environmental conditions were constructed by integrating wind and wave observations from Typhoon Gaemi (2024). The hydrodynamic behavior of the platform was analyzed using Ansys AQWA, wind fields were generated with TurbSim, and fully coupled numerical simulations were conducted in OpenFAST to reproduce the motion and load responses of the floating wind turbine under various operational scenarios. The analysis encompasses 6-DOF platform motions, as well as the time histories, statistical characteristics, and equivalent fatigue loads at critical structural locations, including tower base and blade root bending moments. Furthermore, a random forest regression model was employed to assess the variable importance of multiple environmental parameters—such as wind speed, significant wave height, wind and wave directions, wind–wave misalignment, and rotor speed—on platform motions and structural loads.The findings indicate that both platform motion and structural load variability are considerably elevated under operational conditions compared to idling states during typhoon events. In the full-period statistical analysis, the mean EFLs at the tower base and blade root were 76.8% and 82.5% higher than those under idling conditions, respectively. The random forest analysis further shows that, under operational conditions, platform pitch is the most dominant degree of freedom affecting both tower base and blade root moment variability. Under idling conditions, pitch remains most influential for the tower base moment, while roll is most important for the blade root moment—with pitch still exhibiting a high variable importance of 0.87. Further investigation into the environmental variables governing key degrees of freedom reveals that wind direction and wind speed are the primary drivers of platform motions, whereas significant wave height and peak period both have variable importance below 0.4, indicating limited impact within the investigated typhoon scenarios. Overall, this study provides a comprehensive reference for the design, assessment, and operation and maintenance strategies of floating offshore wind farms in typhoon-prone regions.