New Algorithm for Adaptive Single-Phase Reclosure on EHV Transmission Lines

It is well known that single-phase auto-reclosure in extra-high-voltage (EHV) transmission lines has the shortcoming of unsuccessful reclosing in permanent faults and arcing transient faults, which may lead to severe damage to power system and equipments. With the increasing requirement on self-healing ability in smart grid, it is important to study on intelligent single-phase reclosure technique that has the ability to detect permanent fault or the arcing transient fault, and then block the reclsoure to avoid blind reclosing. In an arc-extinguished transient fault, for the initial charged energy in shunt reactors, the current in shunt reactor of the faulted phase exists a free oscillation component in recovery period, whose amplitude is close to or higher than power frequency component , whose frequency is lower and close to power-frequency. Moreover, in the case of an arc-extinguished single-phase transient fault, the character of its current in the shunt reactor are different from permanent fault. A PRONY-based signal analysis method is developed to identify the current in the shunt reactor, then fault nature can quickly be detected according to the swing and frequency of the different signals. The method is tested by a lot of simulations.