Abstract: The sparse least squares support vector machines(SLS-SVM) is used to simulate wind speed of true wind field, and time-varying wind load caused by stochastic wind speed is then obtained based on the aerodynamics theory. A coupling gear-bearing dynamic model of planetary gear system of wind turbine is built by using lumped-parameter method, the model includes time-vary mesh stiffness of gear pair and time-vary stiffness of rolling element bearing. Numerical method is used to simulate the planetary gear system, and the dynamic meshing forces of each gear pair as well as dynamic bearing forces of each bearing are obtained. Then the load varying process is taken as a random process, the cumulative distribution function of equivalent load under the random load is derived. The time-dependent reliability model of the gears and the bearings in transmission system of wind turbine is established by using the stress-strength interference theory, and the dynamic reliability index and dynamic reliability of the gears and the bearings are obtained by using order-second moment method and perturbation method, and then the time related reliability variation laws of the gears and the bearings as well as the transmission system are studied. The research results lay a foundation for dynamic reliability design of gear transmission system of wind turbine.

Key words: Gear transmission system, Random process, Time-dependent reliability, Wind turbines