Single-pole tripping is a technique employed to clear temporary single-line-to-ground faults on transmission lines while maintaining system stability and power transfer. In the single-pole-open state, electrostatic and electromagnetic coupling from the energized phases (and potentially parallel lines) can sustain the fault on the open phase through the ionized channel created by the primary fault. This phenomenon, known as secondary arcing, can significantly extend the time it takes for the arc to extinguish.
Existing reclosing schemes typically incorporate a fixed dead time before reclosing. This dead time is an estimate to allow for secondary arcs to extinguish and for dielectric strength to build sufficiently to withstand full nominal phase voltage. However, depending on system and fault characteristics, this dead time may be longer than required. Conversely, the fault might be permanent, or secondary arcing could persist beyond the dead time. In both scenarios, reclosing should be blocked.
To address these challenges, this paper introduces an algorithm that detects faults on the open phase by using only local voltages and currents. Specifically, the algorithm identifies the presence of arcing and bolted faults that persist through the end of the dead time. Additionally, it can detect the extinction of secondary arcing before the dead time expires. The outputs of the algorithm can be used to shorten reclosing dead time when secondary arc extinction is detected or to block reclosing when a fault is still present at the end of the dead time.
The proposed algorithm is applicable to both uncompensated and shunt-reactor-compensated lines and performs well for both transposed and untransposed lines. It requires that the self- and mutual impedances and capacitances of the line be known.
This paper delves into the problem of secondary arcing and existing solutions. It proposes an algorithm to detect faults or secondary arcing on the open phase during single-phase-open conditions. Finally, the paper validates the algorithm’s performance against field events and simulations.