Magnetic equivalent circuit modelling of doubly‐fed induction generator with assessment of rotor inter‐turn short‐circuit fault indices

In this study, a wound rotor induction machine, as the core of a doubly‐fed induction generator (DFIG) system, is modelled using the magnetic equivalent circuit approach. The entire DFIG system is implemented in Matlab/Simulink environment, including the machine model, power converters, control system and the grid. The model, which includes the ability to simulate rotor inter‐turn short‐circuits (RITSCs), is subsequently used for the investigation and comparison of the impact of this fault in several DFIG quantities, namely in the stator current and in some control variables. This research also deals in detail with the differences found when comparing RITSC and unbalanced rotor resistance (URR) faults. It is observed that on the contrary to the URR, the stator current spectrum is more appropriate than the control signals for the detection of RITSC. Simulation and experimental results obtained with a DFIG system operating at sub‐synchronous and super‐synchronous speeds, for different values of the active and reactive powers injected into the grid, corroborate the findings reported in this study.