Stator-Winding System Excitation Coupling Characteristics And Vibration Response Analysis In Synchronous Generators

Generator is an important equipment used to convert electrical energy,with a complex mechanical structure.The vibration coupling phenomenon between the various parts of the generator is an important content of the generator condition monitoring.Therefore,this thesis investigates both the excitating and response characteristics of the first and the second order forced vibrations in the generator stator-winding system under normal and axially static air gap eccentricity(ASAGE)fault.The excitation expressions of the first and second order forced vibration of the stator end windings under normal and ASAGE fault are firstly deduced,and comprehensively analyzes the excitations coupling characteristics of the first and second order forced vibration in time domain phase and spatial direction.Then,using ANSYS Electromagenetics and ANSYS Workbench finite element calculation software to jointly calculate the first and second order forced vibration excitations and vibration response,and preliminary verifying of the theoretical analysis results.Finally,based on one set of unique experimental devices which can be independently simulated the first and second order forced vibration of end winding to further verify the theoretical analysis and finite element calculation results.The main conclusions of this paper can be summarized as:(1)under normal and ASAGE fault,the direction of electromagnetic force on both sides of end windings under four typical magnetic field distribution conditions is almost completely symmetrical.(2)ASAGE fault can cause the unbalanced axial forces of end windings,which will easily lead to the windings fall out or violent vibration in axial direction,due to the unbalanced end region magnetic field in the rotor’s evacuated and extended ends.(3)Under normal and ASAGE fault,the excitations of the first and second order forced vibrations have no phase difference in the time domain phase,and the angle between their spatial directions is always an acute angle,so the coupling relationship between the first and second order forced vibrations is additive.This paper not only found the coupling relationship between first and second order vibrations was additive,but also investigated the reason why the first and second order vibrations could strengthen each other’s amplitude on the root.These discoveries are of great significance for further research on the vibration mechanism of the stator core-windings system,and can also provide reference for the improvement of vibration suppression in generator design.