Study On Coupled Dynamic And Mooring System Of Submerged Floating Wind Turbine

With the development of offshore wind energy and the development of wind power technology,offshore wind farm development to deep sea gradually.Floating foundation is flexible in installation and relatively small affected by water depth,it can meet the demand of deep sea wind power development,and has good prospects for development and application.This paper selected the submerged floating wind turbine form designed by Wind power research group of Tianjin University.Study on the coupling dynamic characteristics of the submerged floating wind turbine system under the combined effect of wind and wave by the method of combining numerical analysis and model test.Establishment of a coupling dynamic model for wind turbine-tower-floating platform-mooring system,comparison and analysis of the motion response characteristics of the TLP,submerged floating foundation and semi-submersible foundation,it was found that the submerged floating foundation has better dynamic characteristics in the medium water depth of 50~200m;Through the study of the dynamic response of the submerged floating wind turbine system under different wind and wave environment loads,it is found that the heave and surge motions of a floating platform are driven mainly by wind and waves,the pitch response of the platform and the tension of the cable line are mainly influenced by the wave load;The physical model test of a submerged floating wind turbine under the action of different wave loads is carried out,comparison and analysis by the results of numerical calculation,the experimental results are in good agreement with the numerical calculation,and the correctness of the numerical calculation is further verified.The influence of the length and pretension of the cable on the coupling dynamic response of the floating wind turbine system,it is found that the difference between the standard deviation of the surge response of the submerged floating wind turbine is increased by 47.2% when the length of the cable is 40 m and 100m;the maximum of the pitch increased by 116.7%;When the cable pretension is from 1500 kN to 4500 kN,the maximum surge is reduced by 42% and the maximum yaw is reduced by 73.7%.Research on the coupling dynamic response of submerged wind turbine with a cable was damaged in normal condition and limit conditions,the results show that the tension of 4# cable tension under the limit condition increased by 60% than that of the complete state,and the safety factor is 1.22,which does not meet the requirements of the standard design.The cable breakage has a great influence on the floating wind turbine.Structural optimization design for submerged offshore floating wind turbine,through comparative analysis of the performance of the submerged floating wind turbine when the diameter of the heave plate and the draft depth of the foundation are different,Selected the diameter of heave plate 20 m,draft 22 m structure,the coupling dynamic characteristics of the wind turbine with different cable arrangements were studied,chose two kinds of layout with better performance,analyzed the coupled dynamic response of the 100 m in the extreme sea state of water depth,the results show that the maximum value of the surge response increases by 26.9% compared with the former,the maximum value of heave response decreases by 56.2%,the maximum value of pitch angle decreases by 63.1%,and the maximum value of yaw angle decreases by 97.3%.The dynamic response of the two kinds of cable arrangement is small,and has good stability and safety.