Stator Interturn Short-circuit Fault Diagnosis in Synchronous Condensers Based on the Third Current Harmonic

With the rapid development of UHVDC power transmission, synchronous condensers with dynamic reactive power compensation capability begin to be applied in recent years. At present, there is still a lack of effective diagnosis methods for the stator interturn short-circuit fault of synchronous condensers. In this paper, the FEA is taken on a TTS-300-2 type synchronous condenser. In order to truly reflect the changing rules of phase current of synchronous condensers in grid-connected operation when the fault occurs, the three-phase current is analyzed under different severity of the faults. Here, we find that the third harmonic of phase current can be a meaningful indicator to diagnose the interturn short-circuit fault in stator windings and identify the faulty phase. Meanwhile, considering the fact that the exciting current needs to change frequently in synchronous condensers, the steady and dynamic characters of phase currents in different exciting currents are analyzed. The effectiveness of the proposed method is also be verified in asymmetric condition. The study of the paper provides a reference for the fault diagnosis for synchronous condensers.