Directional relaying during single-pole tripping using phase-change in negative sequence current

Single-pole tripping (SPT) operation imposes problem to many power network relaying schemes. In this paper the directional relaying issue for faults during SPT condition is addressed. Algorithms applying negative sequence components of fault voltage and current for directional relaying find limitation during SPT as the prefault signals also contain negative sequence components. This paper proposes a directional relaying algorithm during SPT using phase-change in negative sequence current. The proposed technique is an attractive option as it does not use the fault voltage signal in the decision process. The technique is evaluated using data simulated with EMTDC/PSCAD for single and double circuit lines and the performance of the algorithm is also evaluated.