Noninvasive Detection of Winding Short-Circuit Faults in Salient Pole Synchronous Machine With Squirrel-Cage Damper

This study presents an analytical and experimental method for detecting internal turn-to-turn short circuits both in the rotor or in the stator in salient pole synchronous generator machines (SSGM) connected to local power grid. Two main measurements are proposed to confirm or discard these electric faults: external magnetic field and external housing vibrations (EHV). In the event of a short-circuit winding fault, a correlation between external magnetic field and EHV is done to reinforce the diagnosis. Furthermore, the electric power injection dependence is analyzed and a noninvasive technique is proposed to determine the state of the SSGM whatever its load. Thus, it is shown that only noninvasive and online equipment can be used to diagnose SSGM. A diagnostic tool has been developed to show the viability of an operative wireless monitoring system on a 76-MW SSGM in an industrial environment.