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Summary 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.

Summary Superconducting fault current limiters (SFCLs), as the novel power system devices, have attracted attentions in the last years. However, in order to achieve the maximum benefit from SFCLs, their interaction with power system should be comprehensively evaluated before equipping the power system with them. This paper investigates the effect of fault resistance and fault distance on the steady‐state fault current reduction ratio (FCRR) of hybrid SFCL. Based on the equivalent circuit model, analytical studies are presented to obtain the relation between 2 abovementioned factors and the FCRR of hybrid SFCL. Then, through the detailed simulation studies, the current limiting behavior of hybrid SFCL is evaluated when the value of fault resistance and the position of fault change in wide range. As a result, although the hybrid SFCL is able to reduce the fault current under different circumstances; however, FCRR significantly varies under outside the control changing circumstances. For far faults and faults with high fault resistance, the FCRR of hybrid SFCL is not as good as the other fault conditions. Hence, in the last section of the paper, the remedial actions to enhance the performance of hybrid SFCL during these conditions are proposed.