Effect of the Static Air-Gap Eccentricity & Stator Inter-Turn Short Circuit Composite Fault on the Generator Circulating Current Characteristics

This paper investigates the stator circulating current characteristics under the static air-gap eccentricity & stator inter-turn short circuit composite faults, and the effect of the faulty parameter development on the circulating current. The air-gap magnetic flux density is firstly deduced, based on which the electromotive force (E.M.F.) difference between the two parallel-branches is obtained. Then the harmonic characteristics of the circulating current, also the relationship between the faulty parameters and the circulating current are investigated. Finally, the experiments are taken on a SDF-9 fault simulating generator to verify the theoretical analysis. The result shows that there will be circulating current of 1st and 3rd harmonics induced inside the parallel-branch loop under the composite faults. Moreover, the development of the stator inter-turn short circuit, the increment of the static air-gap eccentricity, and the rise of the exciting current will all make the 1st and 3rd harmonic components of the circulating current increased. The investigation presented in this paper will be beneficial to the failure criterion and the diagnosis of the static air-gap eccentricity & stator short circuit composite fault of turbo-generator. Copyright (c) 2012 Praise Worthy Prize S.r.l. - All rights reserved.