Study On Flexible Multi-body Dynamics And Optimization Design Of Large Scale Wind Turbine Drive Train

With the increase of installed capacity of wind power in the world,the development of wind tubine is going to be in large scale and to the sea.The drive chain of large-scale wind turbine is an important device which transforms the kinetic wind energy into electric energy.The drive chain of a wind turbine consists of blades,hub,main shaft,gearbox,generator and etc,which is a large and complex multi-body coupling system.It is of great theoretical value and engineering significance to establish an accurate dynamic model for the vibration response prediction,resonance identification and dynamic design of large scale wind turbine drive chain.Taking the drive chain of a 8MW large-scale wind turbine as the researching object,the flexible multi-body dynamic model is established,and the dynamic response characteristics of the system are analyzed,as well as the natural frequences are obtained.The effect of flexibility of different types of structures is studied,and the potential resonance points of the system are identified;the dynami c optimization design of the housing and gears are carried out with the goal of reducing the resonance risk and system vibration.The main research contents are as follows:(1)The kinematic and dynamic formulas of flexible multibody are derived.Combined with the actual parameters of a 8MW large scale wind turbine,based on the system coupling topological relationship of the transmission chain,using the SIMPACK multi-body dynamics simulation platform,considering the flexibility of the main shaft and the full flexibility of the gearbox,the flexible multi-body dynamics model of the drive chain is established.(2)The time-varying meshing stiffness,dynamic contact stress,gear angular acceleration and vibration acceleration of the gear transmission system are analyzed,and the dynamic characteristics of the system are studied by combining the time/frequency analysis method.The components in the transmission chain are classified.Based on the full flexible body dynamic model of the gear tra nsmission system,the effect of different structural flexibility on the dynamic response of the system is studied,which can provide theoretical basis for the dynamic modeling and analysis of the drive train of large scale wind turbine.(3)Based on the result of the first 300 natural frequencies of the system,the potential resonance points of the transmission chain are identified based on t he frequency principle,damping principle,energy principle,speed level principle and Campbell diagram.Six potential resonance points of the system are obtained and the vibration modes of which are given,which provides a reference for the optimization design of gearbox.(4)According to the optimization design method of vibration reduction and avoidance of gear transmission system,the optimization parameters of the box,the optimum macro dimension of the second stage gear and the meshing misalignment parameters of the parallel stage are determined.Using the flexible multibody dynamic model of the transmission chain,taking the increment of the system weight as the boundary condition,parameters of the box are optimized;using the flexible multibody dynamic model of the gearbox,taking the lowest vibration acceleration response as the goal,the macro parameters of the second stage planetary gear train are optimized;establishing the flexible multibody dynamic model of the parallel stage,the effect of misalignment on dynamic response of the system is studied,as well as the range of misalignment parameters of parallel gears is obtained.