Analysis of Stator Core Magnetic Tension under Inter-turn Short Circuit of Excitation Winding

Abstract

The characteristics of unbalanced magnetic tension of stator core before and after the inter-turn short circuit fault of excitation winding of synchronous generator are analyzed in this paper. Firstly, the expression of air gap magnetic density and stator core magnetic tension under normal condition and inter-turn short circuit fault of excitation winding are analyzed theoretically. Then, a two-dimensional model was established based on CS-5 synchronous motor, and nine force analysis points were set up in the stator core, what’s more, the magnetic tension simulation analysis was carried out for the nine analysis points. Finally, the mechanical response characteristics of the stator core under normal working conditions and inter-turn short circuit of excitation winding are verified by experiments. The experimental results are consistent with the theoretical analysis and simulation analysis results. The results show that even frequency doubling occurs in the air gap flux density after the inter-turn short circuit fault occurs in the field winding. The magnetic tension per unit area of the stator core has an odd frequency doubling, and the force increases with the increase of short circuit degree. The maximum stress point of the stator core is located at an Angle of about 45 degrees with the central axis of the big rotor tooth, which provides a basis for setting the stress monitoring point of the stator core and fault diagnosis.