Abstract
This paper explores the influence of inductive Distributed Flexible AC Transmission System (D-FACTS) devices on the response of mho elements and quadrilateral distance elements. D- FACTS represents a distributed solution for relieving congestion in transmission lines, but the presence of these devices may cause misoperation or an undesired trip of the protective relay because of overreaching or underreaching of distance elements. This work examines the unpredictable changes in the dynamic behavior of the memory polarized mho circles and the tilt angle value of the quadrilateral distance elements in the presence of D-FACTS, and how that may influence the fault resistance coverage. The results show that implementing D- FACTS on an adjacent line expands fault resistance coverage for forward faults and avoids unwanted tripping in case of reverse faults. For the quadrilateral distance elements, this may cause underreaching or overreaching of the distance elements by changing the tilt of the effective impedance response.