| In recent years,with the rapid development of wind power field in China,the new installed capacity of wind turbine has increased dramatically year by year,and it is developing towards the direction of large-scale and high-power.The wind turbine gearbox is the core component of wind turbine,its performance directly affects the normal operation of the whole wind turbine system.Due to the influence of external time-varying wind load,the problem of transmission system damage and vibration and noise aggravation often occurs in the wind turbine gearbox,so it has become a research hotspot in the field of domestic and foreign industries.In view of the variability of the operation conditions of the wind turbine gearbox and the inadaptability of determining the gear modification amount under a single working condition,taking a 2.5MW wind turbine gearbox as the research object,the transmission and response characteristics of the gearbox in the whole life cycle are analyzed and optimized by establishing a rigid flexible coupling model.The main research contents are as follows:Firstly,the basic structure and transmission principle of a megawatt wind turbine gearbox are analyzed.Considering the deformation of each flexible part of the system,the flexible part and transmission system are coupled by editing the connection of bearing hole nodes,and the rigid flexible coupling analysis model of the gearbox is established.Based on the static analysis and relevant standards,the contact and bending strength of each gear under rated and ultimate working conditions,the stress and life of each bearing,the stress of each box component and planet carrier are analyzed.Secondly,in view of the long operation period and complex and changeable working conditions of the wind turbine gearbox,in order to explore the variation law of the internal excitation and vibration response of the gearbox under different working conditions in the whole life cycle,the 20-year rain flow counting load spectrum of the wind turbine gearbox is transformed in time domain,and 10 main working conditions of the gearbox in the whole life cycle are obtained through the discrete time domain main shaft load curve.Based on this,the time-varying meshing stiffness,transmission error,meshing impact and external vibration response of the gearbox are analyzed.Thirdly,in order to better the internal excitation and vibration response of the wind turbine gearbox in the whole life cycle,the method of gear macro parameter optimization is applied to increase the coincidence degree of each gear pair in the gearbox and the meshing stability of the gear is improved.At the same time,the transmission and response characteristics of the gearbox are improved based on the micro modification method.In view of the inadaptability of determining the gear modification quantity in a single working condition,the optimization design scheme of the modification quantity based on BP neural network and genetic algorithm is proposed.By establishing the modification quantity of each gear and the parameters of differentworking conditions as the input quantity and the peak-to-peak value of transmission error of each gear pair as the output quantity,the prediction model of BP neural network is established,and the minimum combination value of peak-to-peak value of transmission error of each gear pair under 10 main working conditions in the whole life cycle is taken as the goal,and the genetic algorithm is applied find out the gear modification quantity amount that adapts to the whole life cycle of the wind turbine gearbox,and the changes of the internal excitation and vibration response of the wind turbine gearbox before and after the gear optimization are compared.Lastly,the simulation model of wind turbine gearbox coupling acoustic boundary element is established.Taking the support force of each bearing as the boundary condition,the changes of the radiated noise of the field point in the whole life cycle are studied before and after the gear optimization. |
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