Abstract: “Large scale wind turbines must reliably operate in the highly dynamically harsh situation due to varying wind source and grid safety under which the dynamic performance of their transmission lines is especially concerned. Thus, dynamic investigations on the gear system considering the change process of speed and torque are endeavored in order to achieve the strict performance requirements. This study uses a discrete three-dimensional (3D) dynamic model of planetary gear system (PGS) in which gear design parameters can conveniently be incorporated. The model is formulated basing on equivalent springs accounting for the effect of varying meshing stiffness of mating gear or bearing pairs.. In addition, the physical models of bearings, shafts, and housing frames are also included. Then, after assigning torque and speed change in operation, the dynamic transient and steady- state responses of gear system concerning the shifting process of rotation speed and loading are solved. The dynamic c”

Keywords: planetary gear system, dynmaic analysis, speed, loading , mehsing force, wind turbine