Vibration Control Strategy Analysis Of CDTMD And Negative Stiffness TMD For Floating Wind Turbine

It is difficult to ensure the stability of offshore floating wind turbine under the combined action of wind,wave and current.How to effectively ensure the smooth operation of offshore wind turbine has become the research difficulty and focus in the field of offshore floating wind power.In this paper,based on CDTMD and TMD-NS,two kinds of surge response dynamic models are established,and the dynamic characteristics of wind turbine driven by CDTMD and TMD-NS are analyzed.The details are as follows:Firstly,based on TMD,MTMD and additional dampers,a solution of installing CDTMD in the main structure to suppress harmful vibration is proposed.The effects of frequency ratio,damping ratio,amplitude ratio and tuning bandwidth are analyzed,and the best damping effect is obtained.In order to minimize the amplitude ratio of single degree of freedom main vibration structure,the optimal parameters of CDTMD are obtained.Secondly,the wave and current loads acting on the lower floating platform and the aerodynamic loads acting on the nacelle and tower are analyzed.Based on the optimal parameters of CDTMD,the mass,spring stiffness and damping coefficient of CDTMD are designed.Taking the basic wind,gust,gradual change wind and combined wind as the actual wind conditions,the simulation time histories of displacement,velocity and acceleration of nacelle and tower are obtained.Thirdly,considering that the negative stiffness can effectively suppress the vibration,the negative stiffness tuned mass damper(TMD-NS)is installed on the main structure with single degree of freedom under harmonic excitation,and the amplitude ratio formula of the main structure is obtained by Laplace transform.On this basis,the optimal frequency ratio,optimal damping ratio and optimal negative stiffness coefficient of TMD and TMD-NS are optimized by using fixed-point theoryFinally,the optimal frequency ratio,damping ratio and negative stiffness coefficient of TMD-NS are applied to the design of mass,damping coefficient,spring stiffness and negative stiffness spring stiffness of TMD-NS in nacelle.The surge dynamic model of wind turbine with traditional TMD and negative stiffness TMD is established.Taking the random wind of three different wind speeds as the wind load input,and taking the 5MW spar floating wind turbine as an example,the vibration suppression effects of displacement,velocity and acceleration of nacelle and tower before and after the control of normal TMD and negative stiffness TMD under different random wind speeds are analyzed.