Study On Dynamic Analysis Of Gear Transmission System Of Large Wind Turbine

With the rapid development of renewable energy,wind power has gradually attracted attention and application as a clean and renewable energy source.The amount of gridconnected wind turbines increase year by year.The gear transmission system is the core of the double-fed and single-stage wind turbine transmission system.The double-fed wind generator gear transmission system is mostly composed of a planetary gear set and a secondary fixed shaft gear set or a multi-stage planetary gear set.The single-stage wind turbine gear transmission system is composed of a planetary gear set.Gear transmission system failures are the main factor in the downtime of wind turbines.The dynamic characteristics of the wind turbine gear transmission system under the condition of health and different faults is analyzed in this research.It is significant for the design and condition monitoring of wind turbine gear transmission system.The main contents of this paper are as follows:Study on the dynamic response of wind turbine planetary gear set with mass eccentricity: The speed-torque cure of the wind turbine planetary gear set is analyzed based on the speedpower tracking curve of the wind turbine.The nonlinear dynamic model of the wind power planet gear with mass eccentricity is established.The effect of speed and eccentricity on the system dynamic response is analyzed.Study on the system model and dynamic response of wind turbine planetary gear set considering the mixed elastohydrodynamic lubrication friction force: The friction arm of each meshing tooth surface is deduced.The mixed elastohydrodynamic lubrication(EHL)friction force between the tooth surfaces is analyzed considering the lubrication between the tooth meshing surfaces.A lumped parameter model of wind turbine planetary gear set considering the mixed EHL frictional friction is established.Numberical methord is used to solve the equations.The effect of rotational speed is analyzed.The correctness of the model is verified by experiments.Study on the dynamic response of wind turbine planetary gear system with cracks: The time-varying meshing stiffness is deduced.The influence of the depth,number and position of root crack on the system dynamic response is studied based on a lumped parameter model.The time-domain characteristics,frequency-domain characteristics and time-frequency distribution of the system response with crack failure are obtained.Study on the influence of electrical fault on dynamic response of wind power transmission system: The electrical average model of doubly fed wind turbine is established.A transient torsional lumped model of wind turbine-gear-generator rotor transmission system is established.The electrical average model is combined with the transient model of transmission system.The effects of single-phase grid voltage sag,triple-phase grid voltage sag and single-phase short circuit of stator on the dynamic response of transmission system and the time-varying meshing force are analyzed.Study on dynamic response of gearing transmission system under flexible support: A nonlinear translation-torsion model of spur gear pair with flexible support of gearbox is proposed.The time-varying meshing stiffness,transmission error and backlash are considered in this model.Lagrange’s equations are used for establishing the mathematic model.The numerical method is presented for solutions of nonlinear differential equations.The effects of rotating speed and support stiffness of gearbox are analyzed.The response characteristics of the flexible support to the system are obtained compared with a dynamic model of the spur gear transmission system under the rigid support.