| With the rapid adjustment of the global energy structure,the proportion of new energy in the energy structure is increasing.Among them,wind power technology has developed rapidly due to its advantages of being clean,extensive and recyclable.On the basis of expounding the working principle and main structure composition of large wind turbine,this paper makes a systematic analysis of the aerodynamic load source of wind turbine,the main unbalanced load source that causes the vibration of wind turbine and the vibration form of each main structure of wind turbine.Combined with the actual situation,through the vibration modal analysis theory and method of introduction,dynamics analysis of the movement process of the wind turbines and monitoring needs,based on the currently mature operating modal analysis method of analysis is made on the structure of the vibration characteristics of wind turbines,and combining the theory of modal parameters for structural state assessment.Combined with the actual operation of wind turbine,the theoretical modal analysis and experimental modal analysis methods are introduced respectively.Firstly,theoretical modal analysis method is used to conduct modal analysis of wind power units.Based on professional wind power design software Bladed,the theoretical modal analysis and calculation of the blades and tower barrel of a wind power unit in service are carried out according to the parameters of a wind farm in Shanxi Province with 1.5mw wind power unit.The 3D modeling software Pro/E was used to conduct 1:1 modeling for the tower cylinder of wind turbine test unit,and the modal analysis was carried out based on the finite element analysis software ANSYS,and the theoretical modal parameters of the tower cylinder were obtained.Based on the theory of experimental modal analysis,aiming at the problem that manual excitation is difficult to realize,the working modal analysis of large power wind turbine in service under environmental excitation is studied.Based on the time-domain method of structural modal parameter identification under environmental excitation--natural excitation method(NEx T),the impulse response function of vibration data under environmental excitation was approximated,and the structural modal parameter identification of wind turbine was realized by combining the characteristic system realization method(ERA).The modal parameter identification results are modified and optimized by means of MPC method,and the noise modes are eliminated.Based on the engineering test,the measured vibration data of 1.5 MW wind turbine in a wind farm in Shanxi Province were obtained.Through MATLAB programming,the vibration modal parameters of the turbine tower are identified,and the working modal parameters of the gearbox and the tower under different working conditions are obtained.The structural state of the tower drum was evaluated by combining the modal amplitude coherence coefficient(MAC)and the working parameters of the wind turbine.The reliability of the identification results of vibration modal parameters of wind turbine based on environmental excitation was verified,and the health monitoring of wind turbine could be realized at the same time. |
