Fault characteristics of the DFIG rotor inter-turn short circuit considering inherent imbalance and static eccentricity

Abstract

The performance of doubly-fed induction generators (DFIGs) would be affected by the rotor winding inter-turn short circuit fault, such as harmonics increase in electromagnetic quantities and torque pulsation. Thus, it is necessary to monitor and diagnose the rotor inter-turn fault for DFIGs. However, the rotor three-phase windings inherent imbalance and static air gap eccentricity may cause misdiagnosis of the rotor winding inter-turn fault. The finite element models of the DFIG are presented firstly, which consider the rotor three-phase windings inherent imbalance and static air gap eccentricity respectively. Then the rotor inter-turn short circuit faults of DFIGs are simulated under both conditions. Based on the characteristics analysis of the stator line voltage, rotor line current and electromagnetic torque from the simulation, a diagnosis method for the DFIG rotor inter-turn fault is proposed, which could avoid misdiagnosis caused by the rotor three-phase winding inherent imbalance and static air gap eccentricity and increase the diagnosis accuracy.