Initial Design And Key Technology Of Support Structure Of Deep-sea Floating Wind Turbine

Offshore wind generation in the deep sea provides rich renewable clean energy. Nowit is inevitable that offshore wind turbine develops from shallow pile style to deep floatingstyle, and it has become the focus field in foreign countries, but it is still at the initial stagein our country. Floating support structure is very important for floating offshore windturbine, but many domestic researches remain at traditional fixed structure style of coastalwater due to lack of mature design standard and analysis software. Therefore, it’snecessary to promote the research of key technology about the support structure of floatingoffshore wind turbine.Firstly, according to IEC design specification related to wind turbine, a preliminaryconcept design of the support structure of floating wind turbine in sea area of Stevenson wasconducted with the professional design software SAMCEF for Wind Turbine. Then, theintegrated flexible multi-body dynamics finite element simulation model of floatingoffshore wind turbine was built. Based on the aerodynamic blade element theory andMorison wave theory, the key technology about the support structure of floating offshorewind turbine under wind and waves was researched. Key research contents and relevantconclusions in this paper are as follows:(1) According to wind conditions of wind turbine design requirements IEC61400-1andmarine environment loads of design requirements for offshore wind turbinesIEC61400-3, the environmental loads standards and the environmental load caseswere chosen. Then a preliminary concept design of the support structure of threepontoons floating wind turbine was conducted and the design points were provided;(2) The support structure of the three pontoons floating wind turbine could keep stablewithout overturning and generating safety under IEC typical standard conditions(normal operating conditions and extreme wind and waves load of a return periodof50years with stop working) are obtained through calculation and analysis. Thestrength of the support key structure of floating wind turbine meets therequirements and chain design also satisfied correlative criterion requirements;(3) It is known that the overall displacement and the key point stress of floating windturbine under normal operating conditions are both higher than that of underextreme wind and waves load of a return period of50years with stop working.These results suggest that the influence of wind loads to support structure of wind turbine under normal operating conditions is very important, which couldn’t beignored for the design of floating wind turbine.(4) The generator power curves of three pontoons floating wind turbine reveals that thegenerator power of the floating wind turbine would increase substantially with theincrement of the wind speed before wind speed to rated rotor speed, and theinfluence of wind speed increased to generator power is not obvious after the windspeed reach to the rated wind speed.(5) Through the analysis of dynamic characteristics of the offshore floating windturbine, it is shown that the low order type of vibration are the overall vibration.Meanwhile, the three buoy floating wind turbine structure could avoid marinefrequency effectively. The higher modes shows local vibration, and the towervibration shows swing, up and down; Moreover, natural frequency of tower androtation frequency of blades do not produce resonance.(6) Under certain wind speed, the wave height of the three buoy floating wind turbinehas great influence on the structure’s stability, so it should focus on the wave height;Under certain wave height and during the range of work wind speed, powerincreases with the increase of wind speed. When the wind speed exceeds the ratedwind speed, wind speed don’t has great influence on the platform.