A Positive-Sequence Directional Relaying Algorithm for Series-Compensated Line

Series capacitor imposes problems to line protection and other online decisions. The directional relaying issues during voltage and current inversions in a series-compensated line are addressed in this paper. A conventional directional relaying algorithm uses fault voltage and current phasors to derive the decisions and, thus, finds its limitation at voltage or current inversion. This paper proposes a fault direction estimation technique for a series-compensated line using phase change in positive-sequence current and magnitude change in the positive-sequence voltage at fault. The technique is evaluated by using data simulated with EMTDC/PSCAD for a series-compensated line, and the dynamic performance of the algorithm is also studied.