In this paper, the comprehensive studies regarding the impact of the thyristor-controlled series capacitor (TCSC) on a conventional distance relay for transmission lines are presented to use the conventional distance relays by proposing a revised setting method. The studies are definitely shown that the TCSC affects the operation of distance relays of not only the series compensated lines, but also the adjacent lines. The proposed method uses the equivalent impedance of the TCSC considering the overvoltage protection element such as a metal oxide varistor(MOV) to calculate the distance relay setting elements which can prevent the mal-operation of the distance relays. To analyze and evaluate the performance of proposed method, simulation studies were carried out with the PSS/E and PSCAD/EMTDC environment.

Thyristor-controlled series capacitor, Distance relay, MOV.