Dynamic Characteristics And Operational Modal Analysis Of Wind Turbine Gearbox

Wind turbine gearbox as the key component of wind generator, suffered irregular and transient impact load because of frequent starting, braking and random wind load, and was installed in the tower tens of meters, so its repair and maintenance were not convenient. Wind power system was very strict to the gearbox: long life usually 20 years, low noise less than 95 db at 1 meter, etc. Therefore it is necessary to analyze gearbox's dynamic performance to reduce its vibration and noise and improve the bearing capacity of it.The thesis is supported by National Natural Science Foundation(NO: 51 075408). Regarding 1.5MW wind turbine gearbox as the research object, coupled dynamic model of gearbox was built by lumped parameter and FE method and its inherent characteristics and dynamic response were solved. Meanwhile experimental test was carried out to the gearbox by operational modal analysis method. It has provided the rational method and theoretical basis to design and analyze gearbox. This dissertation's main work is as follow:â‘ Transmission system's torsional model and box model of 1.5MW wind turbine gearbox were built by lumped parameter and FE method. These two models were coupled by support force to form the dynamic model of wind turbine gearbox.â‘¡The dynamic differential equations of transmission system were solved by Runge-Kutta method to obtain gearbox's torsional vibration characteristics and dynamic meshing force, which considered the time-verying meshing stiffness ,system damping and transmission error.â‘¢Coupled dynamic model's constrained modal was calculated by FE method to get its inherent characteristics under the conditions of actual support. Based on FE model of gearbox, calculating box's dynamic response at five different external stimulus, which dynamic meshing force was acted on.â‘£The inherent characteristics and vibration response of gearbox at 30%, 50%, 80%, 100%, 110% of rated power were obtained by operational modal analysis method based on its measured response data. The results of measurement and calculation were compared to verify correctness of the established model.