- 學位論文
浮體式風力機受風與波浪耦合作用下運動之數值模擬研究
Numerical Simulation of Floating Wind Turbine Motion under the Coupling of Aerodynamic and Hydrodynamic Loads
摘要
本論文探討Spar型浮體式風力發電機及Semi-submersible型浮體式風力機受風與波浪耦合作用下運動之數值模擬研究。研究方法為求解雷諾平均那維爾史托克方程式，並選用適當的紊流模型及搭配額外JAVA副程式來考量錨鏈力。風力機部分為NREL 5MW，陸上運轉模擬結果與NREL之資料相驗證，轉子功率計算結果與資料趨勢符合，誤差皆於8%以內。海上運轉模擬部分在均勻風速11.4 m/s，以及波高4 m，周期10 秒、波向角0度之規則波中進行縱搖運動及同時開放縱移、浮沉及縱搖三自由度運動。由模擬結果顯示浮體式風力機因縱搖運動造成的功率變動量可觀，如考慮真實風力機之控制情形，平均功率則會耗損。 由Spar型浮體式風力機進行開放縱移、浮沉及縱搖三自由度運動之海上運轉模擬結果為例，縱搖角度範圍為-3.59 ~ -6.03度，且風力機在運動過程中，功率變動量達+32% ~ -36%，平均功率減少1.39 %，如考慮真實風力機之控制情形，平均功率則減少9.17%；而Semi-submersible型浮體式風力機進行開放縱移、浮沉及縱搖三自由度運動之海上運轉模擬，縱搖角度範圍為-3.50 ~ -5.04度，在運動過程中，功率變動量達+6% ~ -10%，平均功率減少0.99 %，如考慮真實風力機之控制情形，平均功率則減少2.61%。根據本研究之模擬結果建議使用Semi-submersible型之浮體平台搭配風力機，以降低實際運轉發電時平均功率之耗損。
並列摘要
This research investigated numerical study of spar type and semi-submersible type floating wind turbine doing motion under the coupling of aerodynamic and hydrodynamic loads. We use computational fluid dynamics package and solve the flow field by using Reynolds-averaged Navier-Stokes equations (RANS) solver with a proper turbulent model and also use the java code to compute the mooring line force. NREL 5MW is choosed as our wind turbine. For the onshore simulation case, the result is verified with the NREL simulation results, the errors are less than 8%. And the offshore simulation case is the wind turbine doing pitch motion or doing surge, heave and pitch motion simultaneously in the wave height 4 m, wave period 10 s regular head wave with uniform wind speed 11.4 m/s. The simulation result shows that the rotor power changes dramatically because of the wind turbine’s pitch motion. And if we consider the real wind turbine control system situation, the average power will be reduced. In the case of the spar type floating wind turbine doing doing surge, heave and pitch motion simultaneously, the result shows that the spar type floating wind turbine has the pitch angle range from -3.59 to -6.03 degrees, and the rotor power change is up to +32 % to -36 %, and the average power is reduced by 1.39%, and if we consider the real wind turbine control system situation, the average power is reduced by 9.17 %. In the case of the semi-submersible type floating wind turbine doing doing surge, heave and pitch motion simultaneously, the result shows that the spar type floating wind turbine has the pitch angle range from -3.50 to -5.04 degrees, and the rotor power change is up to +6 % to -10 %, and the average power is reduced by 0.99%, and if we consider the real wind turbine control system situation, the average power is reduced by 2.61 %. According to this research, we recommend the semi-submersible floating platform in order to reduce the floating wind turbine’s power loss.