Analysis Of NVH Characteristics Of Megawatt Level Wind Turbine Gearbox

Wind turbine gearbox is the core component of wind power equipment, its dynamic characteristics have a direct influence on the performance of wind turbine, and it has become an important direction of research at home and abroad. Taking 2MW wind turbine gearbox with a structure of one planetary stage and two parallel stages as the research object in this paper, establish NVH analysis model of gearbox system, and analyze vibration and structure noise. It is of great significance for reducing vibration and noise of the system to conduct the research.The main contents of this dissertation are shown as follows:(1) Analyzing structure style and transmission principle of a megawatt level wind turbine gearbox, transmission system is coupled to structure system in bearing node and the mechanical analysis model of wind turbine gearbox is established. The strength of the key parts of the system is analyzed. Based on ISO6336 standard strength of gears is checked, in consideration of deformation of shafts the force, torque and the safety factor of dangerous section are calculated, and stress analysis and fatigue life calculation of bearings are done.(2) NVH analysis model of 2MW wind turbine gearbox is established. Considering the flexibility and deformation of structural system, time-varying meshing stiffness and transmission error are obtained and the internal excitation of system is obtained. The research on NVH characteristics of the system is done, vibration response of system is obtained, and the structure noise is calculated by the one-third octave method. The results of research show that the trend of vibration(displacement, velocity, acceleration) at the same position is consistent, and vibration trend at two bearing seat on high speed shaft in the downwind is basically the same, and vibration at the right bearing is larger than that at the left bearing.(3) Effects of gear macro parameters and gear modification on NVH characteristics of system are analyzed. With the optimization of macro parameters of gears, NVH performances before and after the optimization are analyzed. According to test data in wind field, load spectrum is obtained by the statistical analysis method. Based on the load spectrum to get the optimum modification amount of gears, comparative analysis of NVH performance of the system with and without gear modification is made.(4) Establishing the remote online monitoring system for vibration of wind turbine, vibration of wind turbine gearbox is tested, and vibration acceleration response under the rated condition is obtained, then structure noise on bearing seat on the high speed shaft is calculated. The comparative analysis of the test results and simulation analysis results is done, and the level of vibration and noise within the allowable range is close to each other.