Performance evaluation of distance relay in the presence of hybrid SFCL

This study presents a detailed analysis about the impact of hybrid superconducting fault current limiter (HSFCL) on distance relay performance through the analytical and simulation techniques. For assessments, two possible installation locations for HSFCL (before or after potential transformer (PT)) are considered here which has not been evaluated in the literature so far. Moreover, the impact of action time of fast mechanical switch implemented in the HSFCL structure on impedance trajectory and trip time is investigated. The obtained results show the adverse impact of HSFCL on distance relay performance in all cases. Specially, for forward faults, the worst case happens when HSFCL is installed at the downstream of PT. Using quadrilateral characteristic instead of mho can improve the performance of distance relay; however, this way does not fulfil the enough security and sensitivity under different conditions. Therefore, two approaches are proposed to overcome these challenging situations: (i) modifying trip region of distance relay with respect to the HSFCL impedance and (ii) the new impedance calculation procedure. The significant aspect of the proposed solutions compared with the existing techniques is that the accuracy of distance relay is improved without using additional hardware to provide information from HSFCL.