Studying a novel method for mitigation of the adverse impacts of SFCL on transmission line distance protection

Abstract

In the situation where the superconducting fault current limiter (SFCL) is installed at the downstream of voltage transformer, the apparent impedance seen by the conventional distance relay changes significantly. In this study, a novel method is proposed to improve the performance of distance protection in the presence of SFCL. The calculated apparent impedance is corrected using the information of the appeared voltage among SFCL terminals during fault conditions. The proposed approach is immune to the impedance characteristic of SFCL during fault conditions. Hence, it is independent of SFCL topology and is able to be applied to different fault current limiting concepts. Moreover, the proposed method has the flexibility so that the sensitivity is kept even if SFCL is not picked up. For verification, three types of SFCL involving the saturated iron-core type SFCL, hybrid type SFCL, and transformer isolated bridge type SFCL are modelled in PSCAD/EMTDC software. Then, the assessments are carried out for factors such as fault type and fault location. The results show the accuracy and simplicity of the proposed approach while keeping the original setting of the protective zone.