Fault ride-through capability investigation of a doubly-fed induction generator with an additional series-connected voltage source converter

In this paper, several published protection schemes applied to fault ride-through capability of DFIGs are compared at first. The voltage sag response of a conventional DFIG with a back-to-back PWM converter connected in the rotor side has been investigated based on both a steady-state DFIG model and a full transient DFIG model in PSCAD. Furthermore, an integration scheme of a DFIG with an additional series-connected voltage source converter is proposed for improving the fault ride-though performance when a DFIG experiences a grid fault on the near side of the point of common coupling (PCC) or remote in the network. The PSCAD/EMTDC simulation results demonstrate the proposed scheme can significantly increase the whole DFIG system stability even following severe symmetrical or unsymmetrical voltage sags.