Analysis on Stator Circulating Current Characteristics of Turbo-generator under Eccentric Faults

Stator circulating current characteristics when under a normal running condition and an air-gap eccentric fault are respectively analyzed, with the analysis results experimentally verified on a SDF-9 fault simulating generator. Experiment results accord with the theory analysis results. In this paper, it firstly deduces the air-gap magnetic flux intensity of normal condition and air-gap eccentric fault, and gains the instantaneous electric potential equation of each stator parallel branch. Then the instantaneous electric potential difference between the two stator parallel branches is further deduced. Based on this, the corresponding air-gap eccentricity conditions are taken into account to detailedly analyze the harmonic components' characteristics of the circulating current and the changing trend between the circulating current harmonic components and the fault parameters. Finally, a diagnosis method for the combined faults based on the circulating current characteristics is put forward. The achievements in this paper are full of reference value and positive meaning for the combined fault diagnosis of air-gap eccentricity and rotor short circuit.