Impact of DFIG-based Wind Turbine's fault current on distance relay during symmetrical faults

Doubly fed induction generator (DFIG) based wind turbine (WT), as a highly penetrated power source in modern power systems, has different fault current contribution from traditional power sources. It has significant impacts on distance relay's performances and may result in maloperation. In this paper, the impacts of DFIG-based WT's fault current on the performances of distance protection are studied in terms of apparent impedance trajectories and fault current expressions, for the symmetrical faults. Based on the apparent impedance trajectories and EMTP simulations, a new kind of maloperation is discovered that the zone-1 distance relay of the lines connecting to DFIG-based wind farms will overreach. And the following analysis indicates that the transient components of DFIG-based WT's fault current are the underlying reasons. With those understanding, suggestions are provided to help prevent the overreach by optimizing the setting of zone-1 distance relay.