| In recent years, wind power industry has developed rapidly. As onshore wind powertechnology has been relatively mature, in addition to the limit of the land resources,developing offshore wind power is necessary, and has its own especial advantages. However,due to the harsh climatic conditions of the ocean, such as the storm winds, billows and the saltspray, it would require much higher technology for the offshore wind power equipment boththe turbine and the support base. Around the whole world, the floating wind turbine for deepwater is still in its experimental and testing stage. Currently, the offshore wind farm in ourcountry which has been put into operation are maily the pile foundation. In the next five years,offshore wind power will come into its new period of heigh development.This dissertation has referred to a lot of materials on wind power both at home andabroad, and has chosed the semi-submersible foundation as the form of offshore wind turbine,which is suitable for the conditions of China’s coastal waters. After that, it designes athree-pontoon semi-submersible platform, which refered to the parameters of5MW windturbine which is proclaimed by National Renewable Energy Laboratory in America. Andthrough making use of the SESAM software, did the relatively complet analysis.Based on the assessment of weight and center of gravity, we disposal the ballast and wasfollowed by the verification and analysis of the performance indicators. Stability is theprimary factor considered in the floating platform, especially for the fan, during its operationthe area above water is rather big, action point of overturning arm is very heigh, for which itwould satisfy higher requirements. In this dissertation the stability is analysesed byhydrostatic stability calculation program. Mainly did the calculation of overall inclinationstability and dynamic stability of the whole of the platform and fan.Both the continue operation of the fan and the stable power supply require relativelystable support platform. Therefore, the impact of the hydrodynamic performance is of greatsignificance for wind turbine power generation efficiency and the life of the generator set.This paper mainly analysesed the influence of the buoy spacing, pole position, dampingplateof the platform, and taking into account the impact of the center of gravity. Viacomparison of the regularities, optimized the model further. Based on the theory of the three-dimensional potential flow theory, while the drag force can be calculate by Morisonformula for small-scale structure. Due to the effect of viscous damping plate can not besimulated exactly, this paper corrected the damping by model test data, and made theshort-term forecasting statistics for the modified hydrodynamic performance result.Numerical simulation results show a good performance of the hydrodynamic.The platform’s structural performance is closely related to the reliability and security ofthe fan, and is the important part of platform performance analysis, whose accuracy of loadassesment is closely related to the forecast reliability of the structural strength. Thisdissertation describes a variety of load calculation method, and select the design wave methodbased on the spectral analysis to assess the load of the fan platform. Based on the ABS rules,this paper conducted the detailed design for the internal structure. Then conducted thestructural load transfer calculation, calculate structural strength. According to the calculationand analysis, the stress response meets the material requirements.Via the analysis of the whole performance，it provides a process and method for the MWwind turbine platform scheme design, and the preference for further research on offshorewind power as well. |
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