Theoretical A Nalysis And Experimental Study On Dynamic Characteristics Of Faulty Wind Turbine Gearbox

In recent years,among all kinds of new energy sources,wind power has received widespread attention from all walks of life,due to relatively mature technology,large-scale development conditions,and relatively low energy costs.As the capacity of wind turbines increases,higher requirements are placed on the performance and reliability of wind turbines.In the event of a failure of the wind turbine,the entire unit needs to be hoisted,and the maintenance period is long.Not only is the maintenance cost itself high,but the shutdown during maintenance also causes a loss of power generation.In order to prolong the service life of wind turbines and improve the reliability of their operation,research on the health monitoring of on-line wind turbines in the non-stop state,fault diagnosis and fault location helps to understand the crew in real time.Operation status,timely warning of failures,scheduled maintenance,and positive guidance for subsequent design improvements.As one of the main components of the wind turbine,the wind turbine gearbox has a high frequency of failure.Temperature measurement,iron spectrum analysis,acoustic and vibration measurements are the main methods currently being monitored for wind turbine gearboxes.Among them,acoustic and vibration measurement is the most popular fault detection method because it has the advantage of determining the fault location.The wind power gearbox dynamics model is the theoretical basis for vibration monitoring of wind turbine gearboxes.Finding an accurate and effective method to establish the dynamic model of wind turbine gearbox is important to the research on the health monitoring,fault diagnosis and positioning of wind turbine gearbox.Therefore,for the FZCR2500 wind turbine gearbox,the lumped-torque coupling dynamics model is established by the lumped mass parameter method.The model considers the planetary wheel meshing phase difference,gear clearance,time-varying meshing stiffness and other factors,and analyzes the effects of translational freedom and common faults on stiffness.Finally,the accuracy and effectiveness of the dynamic model of the gearbox transmission system are verified by experiments.The main research contents of the thesis are as follows:1)According to the structure of wind turbine gearbox transmission system,its structural characteristics are analyzed,and its transmission ratio and characteristic frequency are calculated.The kinetic energy and potential energy of the system are analyzed.A dynamic model of the wind turbine gearbox transmission system was carried out using the second type of Lagrangian equation.2)The time-varying meshing stiffness of the gear and the relative displacement on the meshing line were analyzed.Based on the potential energy method and the improved potential energy method,an analytical method considering the translational freedom is proposed for the angle of the calculation process.The influence of the meshing stiffness of the gear pair on the meshing direction and translational freedom is analyzed.3)The parameters of each gear pair of the gearbox are analyzed,and the conversion method from system freedom to gear pair parameters is proposed.By calculating the stiffness of each gear pair at rated speed,the accuracy and effectiveness of the meshing frequency of each stage and the conversion method from system freedom to gear pair parameters are verified.4)For the two common faults in the gearbox(tooth surface pitting and root crack),the influence of the fault on the gear mesh stiffness is analyzed.By calculating the stiffness of each gear pair at rated speed,the accuracy and effectiveness of the gear rotation frequency and the conversion method from system freedom to gear pair parameters are further verified.5)Taking the scaled prototype of the wind turbine gearbox as the object,build an experimental platform and collect vibration data.The simulation data is obtained through the gearbox C++simulation program written in C++.The time domain and frequency domain of experimental data and simulation data are analyzed to verify the accuracy and effectiveness of the dynamic model of the gearbox transmission system.