Hydrodynamic Performance Of A New Semi-Spar Offshore Wind Turbine Platform And Its Mooring System

With the increasing global demand for new energy,the development of wind power industry is faster and faster.Relevant research topics have become a hot topic in scientific research and engineering circles.At present,offshore wind power research is mostly focused on offshore wind power,while deep-water areas with water depth greater than 60 m have large wind speed,long duration,stable wind speed,and most of the offshore wind power resources are hidden there.The selection of fan support foundation is very important.Pile foundation and other wind turbine foundations,which are widely used in offshore areas,can not meet the requirements of deep-sea development.Floating offshore wind turbine technology needs to be developed.Floating offshore wind turbine is mainly composed of wind turbine,floating foundation and mooring system.Referring to the Semi-Spar concept adopted by Kincardine turbine in Britain,and combining with the advantages of the spar foundations and semi-submersible foundations,a new type of offshore floating wind turbine platform model is proposed according to the 5 MW wind turbine parameters published by the National Renewable Energy Laboratory of the United States.Based on the three-dimensional potential theory,the AQWA software is used for hydrodynamic calculation,and the amplitude-frequency response curve is obtained.It is found that the pitch amplitude of the foundation of the new Semi-Spar floating platform is smaller than that of the general semi-submersible floating platform,and the hydrodynamic performance is good.By studying the influence of pontoons spacing and pontoon diameter on the hydrodynamic performance of floating foundation,the results show that increasing the distance between pontoons can reduce the amplitude of motion relatively,and increasing the diameter of pontoons will increase the amplitude of heave.By calculating the motion response and acceleration results of the floating foundation under irregular wave in frequency domain,the most unfavorable wave direction is obtained and the reliability of the new platform is verified.According to the environmental load parameters,the mooring system and the anchor chain parameters are designed.The dynamic response and the mooring tension response of the whole system under the combined action of wave load,wind load,current load and mooring force are studied by time domain coupling analysis method.The results show that the pitch of the floating foundation is small and the movement of the floating foundation is stable,which is beneficial to the efficiency of the wind power generation and the mooring tension meets the requirements of the specifications.By studying the influence of mooring parameters such as mooring angle,mooring cable number,fairlead position and Pre-tension on the motion response and mooring tension of floating foundation,the general variation law is obtained,which provides a basis for the design and optimization of mooring system for floating offshore wind turbine platform.