Simulation And Analysis For Dynamic Response Of Offshore Floating Wind Turbine System

In the long term,the importance of renewable energy has been realized.Great attention is increasingly paid to the wind energy,which has been the most widely used and the most established resource of renewable energy.Offshore wind power has the advantages endowed by nature of ample wind with high quality and broad space for wind farm.With further step into deep water and the cost reduction Offshore Floating Wind Turbines(OFWT)may offer,large-sized OFWTs turn into a focus of wind power research.OFWTs would be suffering from multiple loads.To compute all the environmental loads in a reasonable and effective way is the key to OFWT research.In this thesis,loads are classified and corresponding methods to simulating them are proposed.Coupled dynamics is a core aspect in analysis of wind turbine,for which a methodology about kinetic modeling for OFWT system has been reached through theoretical derivation.The multi-body model is introduced to include the complicated degrees of freedom and several slender structures in OFWT.A hybrid coordinate description for motions and deformation of each component is utilized.Based on the theory of continuum mechanics,a coupled equation for rigid-flexible coupling model of spatial beam is obtained.With the employment of Kane?s method,an equation for rigid-flexible hybrid multi-body dynamics is presented in the thesis.Various kinetic models for OFWTs are established according to rigid body dynamics and multi-body dynamics,where the transformations for loads in different models are stated.DAROFWT,a program for simulating OFWTs in time domain is developed and five models for wind turbines in various situations are provided.The aero,elastic,hydro,and mooring characters of OC3-Hywind system are explored by DAROFWT.Research about the effect of platform motion on kinetics of wind turbine and the response of the system in wind-wave combined conditions are performed to investigate the coupled dynamics of OFWTs.Five models from DAROFWT are compared due to their behavior in simulating OFWTs.