| Under the associative action of high head, high flow rate and strong electromagnetic field, the severe vibration of hydraulic turbine-generator units occurs frequently. The severe vibration strongly affects the normal, safe and stable work of hydropower station, which hasn't been thoroughly proved up yet. It was attempted that by analyzing the fluid-structure interaction and electromechanical coupling relations of hydraulic turbine-generator units, board shell element expressing fluid-structure interaction, generator element incuding nonliner term of electromagnetic excitation and chief-axis element incuding geometric nonlinearity caused by the large deformation of lateral direction were established by the finite element methods from the point of view of global coupling. On the basis of those, nonlinear dynamic equation of Francis hydraulic turbine-generator system was established to provide a new analysis model for further analysing the vibration mechanism of system.The dynamic model of nonlinear was analysed by multi-scale analysis method.In the course of analying the square and cubic nonlinear characteristics of the model respectively, found some certain resonance in the time the system operating,such as intrinsic resonance, multiple resonance and subresonance.And multiple resonance, ultra-harmonic resonance and subharmonic resonance were made the study of to obtain some qualitative conclusions.For example,in certain conditions, energy penetration phenomenon exists between freedom of motion.Certain example was simulated by programming.It was shown that the established model was substantially correct by comparing simulation results with experimental data.The simulation results show the system exists many kinds of resonance and initially revealed vibration mechanism of the Francis hydro-generator system.Those provide a clear clue to further in-depth and meticulous study of the various conditions of the existence of resonance and finding the law of resonance.
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