Investigation on Stator Circulating Current Characteristics of Turbogenerators under Air Gap Eccentricity and Rotor Short-circuit Composite Faults

This article investigates the characteristics of the stator winding parallel branches circulating the current of turbogenerators under air gap eccentricity and rotor inter-turn short-circuit composite faults. The presented current characteristics are achieved from the theoretical derivation of the electromotive force difference between two parallel branches and are verified by the experimental results. Three types of the composite faults are studied. The theoretical analysis and the experimental results show the significant difference of the circulating current characteristics between a normal condition and a composite fault condition. An effective diagnosis method for the composite faults based on the circulating current increment is proposed in the end. The investigation results of this article will be beneficial to the composite fault diagnosis of turbogenerators.