Research On Thermoelastic Coupling And Vibration Response Of Gear Transmission System Of Wind Turbine

With the development of wind power generation technology,wind power generation has become an easy way to develop,renewable,green power generation.The wind wheel converts wind energy into mechanical energy,which will be transmited to the generator rotor through the transmission system and eventually converts into electrical energy.Due to the complex working conditions,such as high layout,high failure rate and maintenance difficulties of the gear transmission system,the clearer understanding of the dynamic characteristics of the gear transmission system,the more beneficial it is to improve the stability of the gear transmission system.In this paper,the 1.5 MW wind turbine gearbox is the main research object and its dynamic response is analyzed under different conditions and different health status based on gear dynamics.The following research was carried out:(1)A 6-DOF wind turbine gearbox high-speed transmission system translation-torsion nonlinear dynamic model under elastohydrodynamic lubrication conditions is established.On the basis of ignoring the non-linear supporting force of the supporting bearing and the bearing,considering the friction between the gear pairs of the gear transmission system,the lumped parameter method is adopted,and the Runge-Kutta numerical method is applied.By changing the parameter values of the gears at different speeds and side clearances Analyze the nonlinear vibration characteristics of high-speed gear transmission system and the law of system vibration response.Based on the elastohydrodynamic lubrication theory,the dynamic response of the gear transmission system at different speeds under mixed elastohydrodynamic lubrication conditions is analyzed.Finally,a D77 large-scale wind turbine was used as the test object to test and verify the correctness of the proposed model.(2)A finite element model of spur gear was established.The thermal behavior of the gear is studied.The convective heat transfer coefficient and frictional heat flux of the gear are theoretically calculated.The thermal analysis results are imported into the contact analysis for thermal-structure coupling analysis.The transmission error and meshing stiffness of the gear under static analysis and thermoelastic coupling analysis are calculated respectively.Considering three levels of pitting corrosion failures,models of different pitting corrosion conditions are established,and the finite element method is used to calculate the time-varying meshing stiffness of gears with healthy and different pitting corrosion failures.(3)A 16-DOF gear-rotor-bearing transmission system nonlinear dynamic model of bending and torsion coupling is established.The Lagrange equation is used to derive the vibration differential equation of the transmission system,taking into account the time-varying meshing stiffness,transmission error,and tooth surface side.The effects of backlash,gear eccentricity,tooth surface friction and the non-linear support force of the bearing are analyzed.The effect of the backlash of the tooth surface on the vibration response of the transmission system is analyzed.At the same time,the influence of the change of the eccentricity on the vibration response of the transmission system is analyzed.(4)The nonlinear dynamic model of the gear transmission system with compound dynamic backlash under pitting corrosion is established.Three dynamic backlash models,including dynamic backlash with fractal characteristics,dynamic backlash that varies with center distance,and compound dynamic backlash are introduced.The compound dynamic backlash model is embedded in the dynamic model of the gear transmission system.The energy method is used to calculate the time-varying meshing stiffness of gears with healthy and varying degrees of pitting failure.Considering the compound dynamic backlash and gears with pitting faults,the motion state of the transmission system with different pitting faults at different speeds is analyzed,and the vibration response and fault characteristics of the gear transmission system with different pitting faults are analyzed in detail.