An Investigation of the Impact of D-FACTS Devices Implementations on the Mho Distance Elements

This paper reports on an investigation of the impact of inductive Distributed Flexible AC Transmission System (D-FACTS) devices implementations on the mho distance elements. D-FACTS can be used as a distributed solution for relieving congestion in transmission lines, but their operation may lead to unpredictable changes in the transmission line impedance and possible limitation of fault current. The presence of these devices may cause failure to trip, unwanted trip, or misleading fault location information. Different types of D-FACTS implementations, such as either compressed or dispersed implementation are examined to show their influence on the protection system performance of the transmission lines by using relay software model and commercial relays. The main objective of this paper is to provide a good understanding of the D-FACTS effect on the protection elements and then to come up with recommendations for D-FACTS implementation and protective relay settings.