Research on dynamic interturn short circuit fault location of exciting winding in turbine generators

The interturn short circuit of the exciting winding is a common fault in turbine generators; however, its location is difficult to be determined with now available methods. Based on principal theories in electrical machines, we deduced the expression of harmonic component variation about exciting magnetomotive force (MMF), magnetic flux density in the air-gap, no-load electromotive force (e. m. f.) and circular currents between stator parallel branches in order to determine the location of the dynamic rotor winding interturn fault of turbine generators. Then, the characteristic quantity and diagnosis method about the dynamic rotor winding interturn fault were confirmed. The presented method was validated by simulative and experimental results. The two ratios were obtained, which one was the ratio of stator odd harmonic e. m. f variations and the other was the ratio of even harmonics of stator parallel branch circulation. They are one-to-one correspondence with the location of the excitation coils interturn short fault. So the location of the short circuit fault can be obtained. The proposed method can be used to detect the location of dynamic and static interturn faults of the exciting winding. © 2015 Chin. Soc. for Elec. Eng..