Determining distance relay Zone-1 reach settings to prevent CCVT transient overreach

This paper presents the results of a study on determining Zone-1 reach settings for transmission line distance relays to prevent overreach resulting from coupling capacitor voltage transformer (CCVT) transients. In particular, this study focused on digital distance relays and determining appropriate relay reach settings to account for the effects of CCVT transients during faults for CCVTs with active ferroresonant suppression circuits. The results of the study presented herein are based on EMTP simulations that were validated by actual relay tests.