Detection Method of Rotor Inter-turn Short Circuit in Synchronous Generator Based on Leakage Flux of Peripheral Components

Rotor winding faults in synchronous generators can significantly degrade operational performance, efficiency, and reliability. This study addresses inter-turn short circuit (ITSC) fault detection in synchronous generator rotor windings by analyzing the leakage magnetic fields in peripheral components, which contain fault-related harmonics following ITSC. A detection coil is circumferentially wound on the stator casing to capture these harmonics. A theoretical analysis is conducted to investigate the air gap magnetic field fault characteristics and main magnetic flux leakage mechanism in a salient-pole generator. Finite element simulations of the SAV620/275/18 hydro-generator model reveal the distributions of leakage fields and the evolution of harmonics under fault conditions. Experimental validation using the MJF-30-6 non-salient pole generator confirms the coil's effectiveness in detecting spillover flux. Both simulation and experimental results show that (k/P)^th fractional harmonic amplitudes in induced voltages correlate with fault severity, providing a robust diagnostic criterion.