On Evaluating Single-Phase Tripping on Distribution Networks

Abstract

Reliability and continuity improvement in distribution system protection and operation has led to the reevaluation of traditional practices in the field. Although these systems employ single-phase protection devices such as fuses, most utilities have avoided the use of single-phase tripping (SPT) schemes in their reclosers. In order to evaluate SPT implementation feasibility on reliability indices and regulatory report perspectives, this paper presents a detailed distribution feeder secondary voltage analysis when the SPT with three-phase transformers over a radial distribution feeder is implemented. Aiming on a practical application, a real overhead distribution feeder was modeled in Alternative Transients Program, allowing protection algorithm implementation and transient simulation. In this paper, three different types of independent phase-interrupting equipment are evaluated: recloser, lateral fuse and transformer fuse. The obtained results are divided into two approaches: the transient analysis, evaluating the voltage behavior on time domain, and the steady-state sensitivity analysis, evaluating the load level impact on secondary voltage level after the single-pole opening as a response to single-phase-to-ground faults.