Analysis of Influence of Uneven Air Gap of Hydrogenerator on Magnetic Field Strength and Rotor Magnetic Pole Stress Change

Abstract

The uneven air gap between the inner cavity of the stator and rotor’s outer circle is one of the main vibration sources of large hydro-generator sets. Unbalanced magnetic tension between the stator and rotor forms a frequency-exciting disturbance force on the rotor and stator. In this paper, in order to explore the relationship between the uneven air gap and the magnetic field strength as well as electromagnetic stress, magnetic induction intensity of inner air-gap magnetic field of the generator and the stress on the rotor surface are analyzed for six working conditions of the hydroelectric generator, including centering and eccentricity of the rotor. The influence of the hydroelectric generator’s air gap change rotor pole stress is studied with finite element software based on the structure of the generator.