A Compositive Diagnosis Method on Turbine-Generator Rotor Winding Inter-turn Short Circuit Fault

Abstract

Generator vibration characteristic and electric characteristic are analyzed when the rotor winding inter-turn short circuit fault has happened. First, the generator parameters of air-gap magnetomotive force, air-gap magnetic permeability and magnetic flux density on the fault are calculated, and the frequency characteristic of imbalance pull acting on rotor and that of pulsating magnetic pull acting on stator core are analyzed, then the rotor and stator radial vibration characteristics are gotten, which are that rotor vibration of fundamental frequency will increase, and stator vibration of second power frequency will decrease for one pair of poles generator. Next, the electric characteristic is analyzed, which is that the second harmonics circulating current between the stator winding parallel branches will increase when the fault occurs. Synthetically considering the vibration and circulating current characteristics, a method of the rotor winding inter-turn short circuit fault diagnosis, based on compositive characteristics of generator vibration and stator current, is developed. Finally, the vibration and circulating current of a type SDF-9 generator is measured in the laboratory to verify the theoretical analysis presented above.