Analysis Of Transverse/Axial Coupling Vibration Characteristics Of Shaft System Of Hydro-generator Set

Under the background of the expansion for the national power system and the diversification of energy structure wind energy,solar energy and other random renewable energy will be more absorbed by the power system.With the increasing proportion of hydropower in the power system,its impact on the safe and stable operation of the power grid has become increasingly prominent,the safe and stable operation of the corresponding hydroelectric generating set has become a front-burner issue in the territory of water conservancy and hydropower project.In-depth analysis of the vibration mechanism of hydrogenerator set will better ensure its operation stability and effectively reduce or even avoid the potential harm caused by vibration failure.In this paper,taking the shafting of hydrogenerator set as the research object,the dynamic characteristics of rotor-bearing system of hydrogenerator set under mechanical and electromagnetic external excitation are analyzed by using rotor dynamics theory and finite element analysis method.The main research contents are as follows:(1)In view of the fact that the axial degrees of freedom are not considered in most of the shafting models established by finite element method in the past,based on the single-node4-degree-of-freedom Euler beam,the axial displacement is integrated into the shafting model,and the corresponding rotor-bearing finite element model of single-node 5-degree-of-freedom hydropower unit is established,which provides the model basis for the subsequent study of dynamic characteristics of shafting system under multi-vibration source excitation.(2)Aiming at the problem of stator and rotor rubbing caused by mechanical and electromagnetic factors,an unbalanced magnetic tension model considering the influence of dynamic and static eccentricities is constructed.On this basis,the vibration characteristics of shafting system of unit under multi-source excitation are studied by means of the combination of Newmark-β method and Newton-Raphson method,and the nonlinear analysis methods such as Poincaré map,axis trajectory diagram,time domain diagram and frequency spectrum diagram are used to study the vibration characteristics of the unit shafting system under multi-source excitation.The effects of axial degree of freedom and axial electromagnetic force on the lateral vibration characteristics of the system are compared.The research results of this article can provide reference for the study of shafting vibration of hydrogenerator sets.