應用於颱風多發的中水深海域之偏軸型半潛之浮式風力發電機繫泊系統之設計與最佳化

Abstract

本論文針對目前學術界對於偏軸型半潛（off-column semisubmersible）之浮式風機在颱風與中水深結合條件下繫泊研究的不足，研究了一種 15 兆瓦偏軸式半潛式浮式離岸風力發電機臺大浮臺（TaidaFloat），在臺灣海峽70公尺的中水深且多颱風的環境下，懸鏈式繫泊系統 ( catenary mooring system) 的設計與優化。本研究使用 ANSYS SpaceClaim、ANSYS Aqwa、OrcaWave 和 OrcaFlex 開發了全面數值框架，模擬浮台水動力學與繫泊動態。此研究中的水動力參數已通過實驗數據驗證，並納入計算流體力學（CFD）計算的阻力係數以考慮風與洋流負載。 本論文使用 Python，基於最可能最大值（MPM）方法估算極端繫泊張力，避免過度保守的設計結果。3x3 全鏈繫泊系統經優化，實現 1,190 公尺錨固半徑，並進一步通過每條繫泊線整合 12 個 8 噸重的配重塊，減少 29% 錨固半徑至 840 公尺，提升繫泊剛性並降低浮台位移和最大繫泊線張力。研究顯示偏軸設計引發偏航 ( sway ) 旋轉，增加繫泊張力，使繫泊系統設計面臨挑戰。這些發現為多颱風的中水深環境下，偏軸式半潛式風機的繫泊設計提供關鍵見解。

This thesis addresses the gap in mooring studies for off-column semi-submersibles in typhoon-prone intermediate-depth conditions by investigating the design and optimization of a catenary mooring system for TaidaFloat, a 15 MW off-column semi-submersible floating offshore wind turbine (FOWT) deployed in the 70 m deep waters of the Taiwan Strait. A robust numerical framework, integrating ANSYS SpaceClaim, ANSYS Aqwa, OrcaWave, and OrcaFlex, is developed to model platform hydrodynamics and mooring dynamics. The hydrodynamic properties are validated against experimental data, incorporating computational fluid dynamics-derived drag coefficients to account for wind and current loads. Utilizing Python, the study applies the Most Probable Maximum (MPM) method to estimate extreme mooring tensions, ensuring practical designs that avoid overly conservative outcomes. The optimized 3x3 all-chain mooring system achieves a 1,190 m anchor radius, reduced by 29% to 840 m through the addition of 12 8-tonne clump weights per line, enhancing stiffness and minimizing offset and tension. The analysis reveals that off-column designs induce yaw rotation, leading to increased mooring tension and posing challenges to mooring system design. These findings provide essential insights for the mooring design of off-column semi-submersible wind turbines in typhoon-prone intermediate-depth environments.