TaidaFloat半潛式浮臺搭載IEA 15MW風機耐海性能實驗研究

Abstract

本研究製作含有錨定系統並搭載IEA 15MW風機的TaidaFloat浮臺1/100縮尺半潛式浮式離岸風機平臺模型，並執行自由衰減實驗與耐海性能實驗。本研究以不同初始運動量進行六自由度運動自由衰減實驗，用以求出各運動方向的自然頻率與不同初始速度與初始角速度對應之阻尼比；耐海性能實驗條件又分為規則波條件與非規則波條件，規則波條件下將執行浮式風機平臺模型在五個不同浪向下的規則波耐海性能實驗，風速條件將以IEA 15MW離岸風機額定轉速下的最大推力反求對應的模型風速，求得在穩定風速條件下浮式風機平臺模型在風浪條件中六自由度運動反應振幅運算子(Response Amplitude Operator, RAO)；非規則波條件模擬臺灣海峽50年回歸週期的極端海況條件，求得浮式風機平臺在極端海況下的六自由度運動反應振幅運算子。由自由衰減實驗結果顯示阻尼比對初始速度或初始角速度為二次曲線關係。規則波耐海性能實驗結果顯示，此浮式風機平臺出現俯仰運動造成的縱移運動、橫搖運動造成的橫移運動與起伏運動造成的俯仰運動；此外在90度與180度浪向條件下，將分別出現較大的浮式風機平臺風機輪轂縱移反應振幅運算子，考量風機發電性能與臺灣海峽盛行季風條件，浮式風機平臺與東北季風風向成45度會是較適合的安裝方式。非規則波耐海性能實驗結果顯示，六自由度運動反應振幅運算子峰值主要出現在非規則波峰值頻率與浮臺各運動方向自然頻率附近，唯橫搖反應振幅運算子受到拍擊(Slamming)現象影響產生很多倍頻局部峰值。

This study conducted free decay experiments and seakeeping performance experiments on a 1/100 scale model of the TaidaFloat semi-submersible floating offshore wind turbine platform. This study conducted free decay experiments on six degrees of freedom motion with varying initial momenta. The purpose of the free decay experiments was to determine the natural frequencies of each motion direction and investigate the influence of different initial velocities and initial angular velocities on the damping ratio. Seakeeping performance experiments were conducted under regular wave and irregular wave conditions. Under regular wave conditions, seakeeping performance experiments were conducted under five different wave directions. The model wind speed was determined by considering the maximum thrust of the IEA 15MW wind turbine at its rated rotor speed. The experiments aimed to evaluate the response amplitude operators of the six degrees of freedom motion of the model under stable wind speed and regular wave conditions. Seakeeping performance experiments were conducted under irregular wave conditions to simulate extreme sea conditions corresponding to a 50-year return period in the Taiwan Strait. The objective was to evaluate the response amplitude operators of the model under these extreme sea conditions. The results of the free decay experiments revealed a quadratic relationship between the damping ratio and the initial velocity or angular velocity. The results of the seakeeping performance experiments under regular wave conditions showed the presence of pitch-induced surge, roll-induced sway, and heave-induced pitch motions of the model. Furthermore, under wave conditions at 90 degrees and 180 degrees, the surge RAOs of the hub become evident. Considering the power generation performance of wind turbines and the prevailing monsoon conditions in the Taiwan Strait, it is more suitable to install the floating offshore wind turbine platform at an angle of 45 degrees to the northeast monsoon wind direction. The results of the seakeeping experiments under irregular wave conditions revealed that peak RAOs were observed at the natural frequencies of all six degrees of freedom. The roll RAO exhibited multiple localized peaks at high frequencies due to the occurrence of slamming phenomena.