Analysis of DFIG machine with rotor-wound faults

Abstract

The round rotor induction machine (WRIM) can be described as a doubly red induction generator (DFIG) when driven above the synchronous speed, and the stator and rotor windings are connected to the whole system. The work in this paper develops a relatively simple powerful model that can accurately analysis the behavior of DFIG with rotor-wound faults. The model is based upon the calculation of the stator current components, which are needed to the build impedance matrix. This method is used here to detect the rotor asymmetry fault on a four-pole wound rotor. Measured torque, current, and power loss results are compared with computer predictions for the machine with a rotor connected to symmetrical or asymmetrical external resistance. An equivalent circuit for a wound rotor induction machine, which includes external resistances, is derived. This is essential for building a better understanding of the fault components computed from the matrix. Simulation and experimental results evidence the validity of the suggested method, leading to an improved condition monitoring system for diagnosing faults in WRIMs.