| With the increasing demand for energy and attention to environment protection, promote the development of clean renewable energy becoming more and more important. As wind energy is renewable and has no pollution, it has greater applied prospect. So, many research institutions are trying to study the development and utilization of wind energy. CoMPared with the limited resourced of the land wind energy, offshore wind energy has more prospects for development. Solid bottom type foundation is only applicable to less than60meters water’s deep, however, the floating foundation which used in deep water has a better character in economy. Currently, deep water floating wind turbine foundation in the international arena is in the testing phase. The technique is still blank in our country, and the related design methods and analysis techniques is far from mature. Therefore, this paper will be based on the characteristics of large offshore wind turbines, and designing for deep sea floating wind turbine foundation, focusing on analysis of the hydrodynamic and structural properties.Based primarily on the characteristics of the deep water floating wind turbine foundation, the type of analysis and the environmental conditions in China’s South Sea, we chose semi-submersible floating as the main subject of this paper. External structural form of the foundation refers to the conception——DeepCWind which origin from University of Maine United States. However, we chose the parameters of5MW offshore wind turbine Renewable Energy Laboratory, and used the catenary mooring system to prevent drift basis. For the chosen semi-submersible floating wind turbine foundation, we first verified its good stability during working and self-existence. Secondly, based on frequency-domain method, we calculated and coMPared the response amplitude factor with or without mooring system and hydrodynamic characteristics factor coefficient. Finally, we analyzed the response with time during the floating foundation working in three directions and two conditions of self-existence in six degrees of freedom in time domain analysis. Hydrodynamic analysis results show that this foundation can meet the requirement of5MW offshore wind turbines with self-preservation. Preliminary, we designed the semi-submersible floating basis of internal structure. In the overall strength analysis, we used a deterministic design wave method and selected seven kinds of design wave which are adverse wave load conditions. We analysis the mode of action in different conditions with loads acted on the structure and check the foundation’s overall strength and buckling strength. The internal structure layout and material selection are the important factors which affect the distribution and the size of stress. This work will provide a reference to the design of semi-submersible floating offshore wind turbine foundation. |
