Dynamic model for doubly-fed induction generators with unbalanced excitation, both with and without winding faults

A detailed analytical model designed for doubly-fed induction generator (DFIG) dynamic analysis is presented. The method employs a coupled-circuit approach and uses the principles of generalised harmonic analysis and complex conductor distribution to develop a systematic method for calculating a circuit´s self-inductance and mutual inductance for windings with any distribution of conductors. As such, it is capable of representing the effects that winding and excitation asymmetries have on machine performance. The accuracy of the model is verified in both the time and frequency domains against experimental results obtained from a specially constructed DFIG test rig, which can be configured to introduce a range of open-circuit and short-circuit faults. Model predictions are compared with experimental measurements for a balanced machine and for the case in which one stator phase suffers an open-circuit fault. The experimental and predicted data are shown to be in good agreement and demonstrate the effectiveness of the technique developed.