Identification and Diagnosis of Stator Inter-Turn Short Circuit Faults Based on Current Harmonic Characteristic Analysis in Synchronous Generators

Abstract

This paper presents a comprehensive study of the electromagnetic characteristic laws of synchronous generator for effective monitoring of stator inter-turn short circuit (SISC). Different from other studies, this paper not only investigates the magnetic flux density (MFD) harmonic characteristics, but also the stator currents and the circulating current inside parallel branches (CCPB) harmonic characteristics. Theoretical calculations, finite element analysis (FEA), and experimental validation were carried out on the MJF-30-6 generator. It is shown that after SISC, the MFD first harmonic amplitude decreases, and the third harmonic amplitude increases. The stator current first harmonic amplitude decreases, but the third harmonic amplitude becomes larger. In addition, when SISC occurs in only one branch or SISC asymmetrically occurs in the two parallel branches, the CCPB will generate the fundamental (first) and the third harmonic, and the harmonic amplitude will increase with the intensification of the SISC asymmetry degree. However, when SISC symmetrically occurs in both the two parallel branches, there is no CCPB, regardless of how the short circuit varies. These united characteristics can be applied to the diagnosis and online monitoring of SISC fault. © 2025 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.