| With the increasing shortage of energy,the development of renewable energy has attracted much attention.After long term of practice,wind power technology has become more mature,resulting in the trend of "from land to sea,from shallow water to deep water and from fixed structure to floating foundation".Offshore wind resource has higher quality,stability,and is free from geographical restrictions.Based on advantages above,offshore wind energy gradually becomes a hot spot of energy development and wind power technology research.In deeper water,floating wind turbines are more economical and the semi-submersible,tension-leg and SPAR floating platforms are widely recognized as offshore floating foundations.Tension-leg floating wind turbines(TFWT)ensure small displacement of surge and pitch,which is conducive to the stable generation of wind energy.Floating wind turbines are subjected to various loads like aerodynamic,hydrodynamic,mooring forces and so on.The tension leg has strong constraint to the motion,and how to accurately and reasonably calculate tendon tension is the key to the research of dynamic response for TFWT.The major content of this paper includes:1.On account of dynamic characteristics of tendon structures,this paper presents a theoretical model and an in-house program for analyzing the dynamic responses of TFWT.Feasibility of this program is then validated by the comparison between the analysis results with the experiment results.The tension-leg mooring system has a perfect stability while tension varies a lot along with platform displacement and has a coupled effect with platform motion.Considering the viscous forces of slender body in waves,Morison method,spectral method and Hamilton method are applied to build a coupled dynamic model and nonlinear equations in order to solve dynamic tendon tension.2.This thesis takes UMAINE-TLP as the research object,and calculates TFWT dynamic responses under joint wind-wave cases by using this in-house program named DARwind.Calculation results are analyzed and compared with experiment data of UMAINE and simulation results using open codes FAST to validate the rationality of the code.In this paper,a simulation program is developed for dynamic responses of TLP-type offshore wind turbines.Results and conclusions in this thesis may benefit the structural design of floating offshore wind turbines. |
