Response And Failure Analysis For A Semi-submersible Floating Offshore Wind Turbine Under Wind And Wave Condition

As the cornerstone of modern society,energy is highly valued by all countries in the world at all times.With the development of society and the enhancement of people's awareness of environmental protection,clean energy is widely used and developed throughout the world.As an important part of clean energy,wind energy is playing an important role in the energy revolution.Because of the adequate and stable wind resources,it's a tendency to develop wind power from land to sea.According to the different bases of offshore wind turbines,it can be divided into fixed offshore wind turbines and floating offshore wind turbines.With the increase of water depth,fixed wind turbines can no longer meet the needs of wind power development in terms of economic costs and structural strength.In order to develop the deep-sea wind power,the world's large-scale wind power development companies and research institutes have put forward the corresponding floating wind turbine conceptual model,and have carried out relevant research on it.The object of this paper is OC4 DeepCwind semi-submersible floating offshore wind turbine proposed by the International Energy Agency(IEA)in Task30.It is suitable for the application in the South China Sea and has positive significance for solving the problem of power supply in coastal sea areas and island reefs,and provides certain technical support for China's maritime power strategyThe first part of this thesis refers to the relevant parameters of the IEA on OC4 DeepCwind and the NREL 5MW wind turbine prototype proposed by the National Renewable Energy Laboratory(NREL).The model of the OC4 DeepCwind semi-submersible floating wind turbine was built,and the hydrodynamic analysis of the semi-submersible floating wind turbine platform was performed based on the potential flow theory in ANSYS-AQWA.The second part of this thesis sets the failure conditions of the two semi-submersible floating wind turbines: breakage of the anchor chain and damage to the cabin.According to the sea condition of the South China Sea,the response of the semi-submersible floating wind turbine and the response of the anchor chain under real sea conditions are simulated,and the comparison of the response of the semi-submersible platform under normal conditions in the time domain is conducted.For specific analysis elements,a comparative analysis is made in the frequency domain.In the third part of this thesis,the improved new semi-submersible floating wind turbine is proposed.In view of the South China Sea and sea environment,the motion response and anchor chain force response of a new type of semi-submersible floating wind turbine under real sea conditions are simulated,and the force response of longitudinal yawing,pitching,and main load-bearing anchor chain are mainly considered and the response is analyzed.