The Research On The Forecasting Of Random Wind Load And The Gear Transmission System Dynamics Of Megawatt Wind Turbine

Due to the more serious energy problem, wind power, one kind of renewable clean energy, has attracted worldwide attentions and the wind power generation technology has also developed rapidly. However, due to the limitation on the working conditions of gearbox and its complex loading condition, gearbox has become the part with highest failure rate in the wind turbine machine set. Along with the increasing requirement of long service life, lightweight and high reliability of mechanical system operation, the research on the mechanical system dynamics generally become more significant. This thesis aims at giving the principles of forecasting the random wind speed of wind turbines with 1.5 MW and the analysis of dynamic characteristics of gear transmission system (GTS). The main research work includes:In view of the random variation of wind speed and the shock of the short-time strong wind, random wind speed forecasting model basing on the fuzzy rough theory of Gaussian kernel function can be constructed and high simulation precision of the forecast wind speed shall be proved. Together with the principle and control strategies of wind energy capture with the aerodynamic theory of wind turbine, the model of random wind load can be built based on the strength of blade tip speed ratio method, which providing the more actual external excitation torque for the accurate solution of the dynamic response of the system.According to the elasticity deformation of the GTS, the changing law of relative displacement in the meshing line can be obtained, and the pure torsional dynamic model of GTS in the megawatt wind turbine shall be established. Considering the influence of the internal and external incentives, such as the time-varying meshing stiffness, comprehensive meshing error, the torsion deflection of shaft, damping and the wind load, the dynamic differential equation of GTS can be determined.Through the solution process of damping-free vibration equations of GTS, the natural frequency of the system and the vibration mode in every component can be got. With the analysis of the torsional vibration equation of GTS, the dynamic changing law of the system can be determined under the common effect of time-varying internal and external incentives such as natural frequency, vibration displacement and the meshing force etc.As for the dynamics problems in the GTS with the function of random wind load, the oil film stiffness and friction coefficient have obvious impact on the dynamic response. Therefore, it is necessary to carry out the gear elastohydrodynamic lubrication (EHL) analysis. According to the meshing state of gear transmission, the gear equivalent model can be established. Together with the line contact thermal EHL theory, EHL model of involute spur gear shall be determined. Adopting multiple grid method to solve gear EHL equation, the changing law of the friction coefficient and oil film stiffness in the dynamics equation can be obtained under different load, wind speeds and gear surface roughness degrees.