Directional Relaying in the Presence of a Thyristor-Controlled Series Capacitor

This paper proposes a fault direction estimation technique for a line with a thyristor-controlled series capacitor (TCSC). Such a compensated line imposes problems to directional relaying schemes due to reactance modulation, current, and voltage inversion issues and TCSC-control action. Three positive-sequence-based classifiers are combined in an integrated approach to estimate the direction of fault for a line with TCSC. The method is tested for different fault situations, such as high resistance fault, close-in fault, as well as voltage and current inversions, and is found to be accurate.