Protection schemes for DFIG considering rotor current and DC-link voltage

This paper presents new schemes for protecting power converters used in doubly fed induction generator (DFIG) during a grid fault condition considering rotor current and DC-link voltage as the key points to be focused on. The different alternative methods for the protection are described, in which two schemes using the coordinated control of the d and q axis measured currents of the rotor side converter and series dynamic braking resistor (SDBR) connected to the stator are proposed and compared. The simulation results in PSCAD/EMTDC show that the two proposed schemes can eliminate the need for an expensive crowbar switch, because both could limit the rotor current of the DFIG within its nominal value during a grid fault.