Multi-condition Dynamic Analysis And Performance Optimization Of Offshore Wind Turbine Gearbox

The proportion of wind power generation in renewable energy is getting higher and higher,and wind turbine is one of the most effective marine engineering equipment to develop offshore wind energy resources.At present,the ultra-high power and large-scale development trend of offshore wind turbines put forward higher requirements for the lightweight design of wind turbine gearbox.Under the action of time-varying wind speed,the coupling deformation of hundred meters large size and large flexible blades and towers will make the input load of wind turbine gearbox produce obvious random characteristics.In addition,the influence of internal excitation such as time-varying mesh stiffness and transmission error leads to the complex vibration characteristics.In this paper,a 5 MW offshore wind turbine gearbox is taken as the research object.Considering the strength differences of gears at all levels,the equal strength optimization design of gear transmission system is carried out to improve the power density.Considering the flexibility of components such as box and planetary carrier and the internal excitation of gear pair,the dynamic model of rigid-flexible coupling system of wind turbine gearbox is established,and its dynamic characteristics under different wind speeds are analyzed.A multi-objective optimization method for micro-parameters of gear pairs under different wind speeds is proposed to reduce system vibration,which is verified by bench vibration test.The main research contents of this paper are as follows :(1)In order to realize the lightweight design of a 5 MW offshore wind turbine gearbox,a multi-objective optimization method for equal strength of wind turbine gearbox transmission system is proposed considering the differences in contact and bending strength of all levels of gears in wind turbine gearbox.The macro-parameters of gears such as tooth number,modulus and tooth width are taken as design variables,and the comprehensive minimum safety factor difference of contact and bending of all levels of gears is taken as the optimization objective.The equal strength optimization design of wind turbine gearbox transmission system is carried out,and the contact and bending strength and power density of all levels of gears before and after optimization are compared and analyzed.(2)Combined with the topological structure of wind turbine gearbox,considering the flexibility of gearbox housing,planetary carrier and shaft,as well as the time-varying meshing stiffness and transmission error of gear pair,the dynamic model of rigid-flexible coupling system of offshore wind turbine gearbox is established.The influence of wind speed on the external excitation and internal excitation of wind turbine gearbox is studied.The planetary bearing force and planetary load sharing performance of wind turbine gearbox under different wind speed conditions are analyzed.(3)The influence of gear pair modification parameters on the dynamic response of wind turbine gearbox under different wind speeds was analyzed,and the mapping function of wind speed condition-gear pair modification parameters-dynamic response was established.To reduce the load sharing coefficient of planetary stage and the vibration response of parallel stage,a multi-objective optimization method of gear pair microscopic parameters at all levels under different wind speeds was proposed.The transmission error,tooth surface load and load sharing performance of planetary stage before and after optimization were compared and analyzed.(4)The bench test of a 5 MW wind turbine gearbox was carried out,and the on-line detection system of the wind turbine gearbox bench test was built.The vibration responses of the bearing seat,torsional arm and inner gear ring of the wind turbine gearbox under rated conditions were tested.The spectral characteristics of the vibration signal were analyzed,and compared with the simulation results to verify the accuracy of the theoretical analysis.