Analysis Of Tripod Support Structure Of Offshore Wind Turbine

Wind energy is a renewable energy that does not produce any pollution emissions. It has the best commercial-scale prospect in the current technical and economic conditions. According to preliminary estimates, there are about1billion kW of wind energy which can exploit and utilize in China, including about750million kW of offshore wind energy. Thus, the potential for wind energy development is tremendous.In this thesis, based on a3.0MW classical Tripod support structure for offshore wind turbine, the static, dynamic and fatigue characteristics of Tripod support structure for offshore wind turbine is studied. The contents of the research include:(1) Combined with the properties of soils, meteorological data and marine hydrological data, the initial support structure model of offshore wind turbine is established, using the finite element software SACS. The analysis cases and related factors according to the specification and documentation are determined. The control case and control load direction of Tripod support structure for offshore wind turbine are analyzed. Then, the comparison of results with previous research is carried out. Finally, the necessity of static and dynamic analysis under multiple cases and multi-direction for the offshore wind turbine structure is also verified.(2) Considering the probability distribution of wind direction and wave direction, fatigue loads are applied to the support structure according to the actual environmental loading direction. Fatigue damage due to the wind load is calculated by deterministic methods; fatigue damage due to the wave load is determined on the base of wave spectrum. Then, the total fatigue damage of the support structure is obtained by linear superposition. Compared with the results that the fatigue damage of the foundation structure is computed under fatigue loads imposed in single direction, the results of omnidirectional fatigue analysis are more reasonable. Although fatigue due to wind is the most significant factor for support structure, the effect of wave on fatigue can not ignored. Finally, more reasonable methods of fatigue analysis for offshore wind turbine structures are proposed.(3) Based on the principle of security and cost, the optimization design is carried out according to the static and dynamic analysis and fatigue analysis of tripod support structure of offshore wind turbine. An optimization design procedure is applied to a typical tripod support structure, and it is proved to be feasible.