A comprehensive study on stator vibrations in synchronous generators considering both single and combined SAGE cases

Abstract

This paper presents a comprehensive study on the stator vibration properties in synchronous generators under varied static air–gap eccentricity (SAGE) conditions. Current studies mainly focus on the electromechanical and thermal properties such as stator/rotor vibration, electromagnetic torque, phase current, stator temperature, etc., in single and combined faults composed of SAGE and winding interturn short circuit, while the dangerous position of the stator core due to the over stator vibrations caused by 3D SAGE is rarely investigated. Differently from the other researches, this work concentrates on the radial magnetic pull per unit area (MPPUA) and the axial unbalanced magnetic pull (UMP) on the stator to investigate the radial and the axial vibrations, taking into account not only the conventional radial SAGE, but also the axial SAGE and the combined SAGE (mixture of radial SAGE and axial SAGE). A 5kVA two-pole prototype synchronous generator, which is designed and manufactured by the authors, is employed as the study object of the finite element analysis (FEA) and the experiment for a validation. The proposed study as well as the 3D eccentricity simulating structure scheme of the prototype generator can be used as a reference for the further/similar investigations. It is shown that the most dangerous position of the stator core is close to the minimum air gap length point. Such conclusion can be employed to detect the detailed 3D eccentricity location and specifically prevent the insulation damage of the stator core.