E ects of Instrument Transformers Connection Point on Measured Impedance by Distance Relay in Presence of SSSC


1 Department of Electrical Engineering,Sharif University of Technology

2 Biochemical and Bioenvironmental Research Center,Iran University of Science and Technology


This paper presents the measured impedance at the relaying point in the presence of a series
connected Flexible Alternating Current Transmission System (FACTS) device, i.e. Static
Synchronous Series Compensator (SSSC). The presence of SSSC on a transmission line has
a great in
uence on the tripping characteristic of distance relays. The distance relay tripping
characteristic itself depends on power system structural and pre-fault operational conditions
and, especially, the ground fault resistance. In the presence of SSSC, its controlling parameters,
as well as the connection point of the instrument transformers of distance relay a ect the
tripping characteristic. Here, measured impedance at the relaying point is calculated, due to
the concerned parameters.