The impacts of distributed doubly-fed induction generators on smart distribution Grid protection

Doubly-fed induction generators (DFIG) used an AC-DC-AC power converter to excite the machine and connected crowbar protection in its rotor side, which makes fault characteristic differ from the synchronic generator's. That may bring problems to traditional current protection in distribution grid. Also, DFIG as a distributed generator (DG) had capability of Fault Ride-Through (FRT), but the tripping principles of the protection installed at point of common coupling (PCC) may disconnect DG when a fault occurred in the Grid. Based on the short circuit current analysis concerned its magnitude and decay time, a compounded current-voltage protection at the PCC is proposed. That scheme could overcome “negative” impact on protection caused by fault current characteristic of DFIG and ensure the DFIG operate under FRT when a fault happens in distribution network..