Asymmetrical Fault Ride-Through Control Strategy for Rotor-Side Converter of DFIG

Abstract

This article proposes an asymmetrical fault ride-through (FRT) control strategy for the rotor-side converter (RSC) of a doubly fed induction generator (DFIG). The mathematical model of the DFIG is presented in the positive and negative rotating synchronous reference frames. To prevent the RSC from overcurrent under asymmetrical fault conditions, both positive- and negative-sequence components of the rotor current are reduced. Considering the voltage capacity limitation of the RSC, the rotor negative-sequence voltage of the DFIG is limited by multiplying by a proportional coefficient. With the proposed control strategy, the DFIG can ride through an asymmetrical fault smoothly even when the imbalanced degree of the grid voltage is equal to 100%. Simulations on a 2-MW DFIG system validate the effectiveness of the proposed asymmetrical FRT control strategy.