Dynamic Characteristics Analysis Of Monopole Wind Turbine Based On TMD

Wind power is one of the most effective ways to solve energy shortage.With the development and improvement of onshore wind turbine research,the limited land resources,and the support of policies,the development of offshore wind turbines has become an inevitable trend.The offshore single-column offshore wind turbines are great promising and potential in China market because of the 180,000 kilometers of coastline belonging to China.The monopole offshore wind turbine is a complex Multiple-physics coupling system.Compared with onshore wind turbines,the operating environment is more complex and changeable under the combined effects of wind and wave varying loads.Under the adverse working conditions,the offshore wind turbines are more prone to serious vibration and service life decrease.At present,the use of a tuned mass damper(TMD)on the fan is an effective method to suppress vibration.However,the quality of TMD is large,and its stiffness,damping and initial installation position have great influence on the vibration of the whole machine.Therefore,it is necessary to study the influence of TMD on the dynamic characteristics of offshore wind turbines and optimize the parameters of TMD.The main contents of thesis are shown follows:(1)The structure composition and transmission principle of the monopole offshore wind turbine system are analyzed..According to the connection relationship of each component,the topological relationship diagram of the wind turbine is created.Considering the flexibility of the blade,tower and column foundation,as well as the random wind load and control strategy,a dynamic model of gas-elastic-water-control system for offshore wind turbines based on TMD is built.(2)The inherent characteristics of the whole system are analyzed to obtain the natural frequency and vibration mode of the complete machine.Based on the screening potential resonance points from the Campbell diagram and modal energy method,the results show:The first-order vibration frequency of the wind turbine is 0.261 Hz.TMD can effectively absorb lateral vibration energy,but does not cause changes in potential resonance points.(3)Under the external excitations of random wind load and irregular wave load,and internal excitations including time-varying mesh stiffness and transmission error,the dynamic response of the fan under start-up,power generation and shutdown conditions are investigated and the vibration suppression effect of TMD is analyzed.The results show that under the shutdown condition,the vibration inhibition rate of TMD on the top end of the tower is 60.82%.(4)The whole machine model of the offshore wind turbine is presented by a twodegree-of-freedom dynamic model through Lagrange energy method.Using the least squares method to obtain the equivalent parameters of the whole machine for the dynamic model.The simplex genetic algorithm is introduced to optimize the mass,stiffness and damping of TMD.The initial installation position of TMD is optimized by substituting the optimized TMD parameters in the gas-elastic-water-controlled wind turbine dynamics model.The results present that the optimal installation range is within 0~1m of the center of the tower base connecting point to the front end of the nacelle;after optimization,the TMD inhibits the displacement of the top of the tower by 68.30% under the shutdown condition.