| As offshore wind turbines gradually move from shallow sea to deep sea,floating wind turbines have become the key direction of offshore wind turbines development due to their advantages of good maneuverability,easy disassembly,and easy towing.However,floating wind turbines are affected by wave loads,wind loads,mooring loads and other loads at the same time,and each load is complex,changeable and coupled with each other.It causes the floating wind turbine platform to generate a large incentive movement,which poses a threat to the safe operation of the wind turbine.Therefore,a semi-submersible floating wind turbine platform with good stability is proposed,and its dynamic characteristics are studied through simulation and experiment.The main contents of this article are as follows:First,a fully coupled dynamic model of the wind turbine system is established with FAST software.Among them,the wind load of the blade is analyzed according to the classical leaf momentum theory,and the wind load of the tower is analyzed according to the wind pressure theory.The three-dimensional potential flow theory is used to calculate the wave loads of largescale upper pontoon,lower pontoon and central pontoon,and the wave load of small-scale support members is calculated based on Morison formula.The mooring load on the floating wind turbine platform is analyzed according to the catenary theory.Secondly,the six-degree-of-freedom motion response of the semi-submersible floating wind turbine platform with circular truncated cone pontoons and the OC4-Deep Cwind semisubmersible wind turbine platform are compared.The results show that the pitch,roll,surge and sway characteristics of the floating wind turbine platform with circular truncated cone pontoons are better than those of OC4.The advantages of platform pitch and roll are the most obvious,and the motion response are reduced by 18.9% and 11.8%,respectively,compared with the OC4 platform,which verifies that the semi-submersible floating wind turbine platform with circular truncated cone pontoons has good stability.Then,the coupled dynamic response of the semi-submersible floating wind turbine platform with circular truncated cone pontoons under different sea states is studied.In order to explore the influence of different sea states on the dynamic response of wind turbine platform,this paper studies the dynamic characteristics of the platform from three aspects: different wind conditions,different wave conditions and different wind and wave angles.The results show that the wind speed change mainly affects the surge,pitch and yaw movements of the platform,and the mooring line tension is mainly related to the surge displacement and pitch angle of the platform.The change of wave conditions mainly affects the heave and pitch movements of the platform,and the mooring line tension is mainly related to the change of the heave displacement of the platform.The change of wind and wave angle mainly affects the surge,sway,pitch and roll movement of the platform,and the mooring line tension is mainly related to the surge and sway displacement of the platform.Finally,the hydrodynamic characteristics test of semi-submersible floating wind turbine platform with circular truncated cone pontoons is carried out.According to the scale ratio of 1:70,the model of the semi-submersible wind turbine platform is built,and the hydrostatic and regular wave tests are carried out.Comparing the experimental results with the numerical calculation results,the following conclusions are obtained: the free decay curves of the model test and the numerical calculation are relatively consistent,and the natural period obtained is relatively close.The model test and numerical calculation show that the trend of platform motion response with wave period is the same,and the numerical difference is small,which verifies the correctness of the numerical calculation results.The platform resonance period avoids the wave trunk cycle,and the overall motion response is small,which verifies the rationality of the design of the semisubmersible floating wind turbine platform with circular truncated cone pontoons. |
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