Impact of DFIG-based wind turbine's fault current on distance relay during symmetrical faults

As a new highly penetrated power source of modern power systems, doubly fed induction generator (DFIG)-based wind turbine (WT) has a different fault current contribution when compared with a synchronous generator. DFIG-based WT's fault current has significant impacts on distance relay's performances and may result in maloperation. In this study, the impacts of DFIG-based WT's fault current on the dynamic performances of two typical distance protection elements, mho and polarisation, are studied in terms of EMTP simulations and fault current expressions in symmetrical fault scenarios. It is discovered that the zone-1 distance relays of the lines connecting to DFIG-based wind power plants tend to overreach. Also, the following analysis indicates that the transient components of DFIG-based WT's fault current and the phasor estimation unit are the underlying reasons. With those understanding, this study is expected to help design new setting methods and for distance protection in power systems integrating wind power plants to prevent this kind of possible overreach.