Investigation of the performance of distance relay in the presence of saturated iron core SFCL and diode bridge type SFCL

Owing to the advance in the development of fault current limiters (FCLs) for high voltage, there is the possibility of using this equipment in transmission systems in the future. However, distance relay that is used to protect the transmission line against shunt faults, is subjected to the more direct impact of FCL installation. In this paper, the effect of the saturated iron core superconducting FCL (SFCL) and three-phase diode bridge type SFCL on the apparent impedance seen by the distance relay, and its trip boundaries are extensively investigated. To perform the evaluations, the impact of SFCL on the measured impedance by the ground and phase distance relays is investigated through the analytical analysis. For evaluations, two possible locations for installation of SFCL including before and after voltage transformer are considered. Finally, both SFCLs are modeled in the PSCAD/EMTDC software, and the effect of each type on distance relay performance is investigated. Fault type, fault location, and fault resistance are the parameters which are considered in the simulation studies. The obtained results show the adverse impacts of both types of SFCL on distance relay performance; however, the impacts of each type are different from another. In this regard, in order to enhance the sensitivity and the security of the relay in this circumstance, the remedial action is proposed.