Arc effect on single-phase reclosing time of an UHV power transmission line

One of the important operational conditions of a single-circuit ultra-high-voltage transmission line is the power transmission by two phases during the clearance of a temporary single-phase short circuit. Such a condition may be sustained for an interval of one second without losing the dynamic stability of the system. The influence of the arc on the single-phase reclosing time of an ultra-high-voltage power transmission line is investigated on the basis of the primary and the secondary arc models incorporated into the transient program EMTP. The validity of the models used is proven by comparison with field test results on an actual 1150 KV power transmission line from Ekibastuz to Kokchetav in Northern Kazakhstan. The processes of this power transmission in the ´dead time´ of the single-phase reclosing cycle are simulated. It is shown in the paper that simplified short circuit simulation without the incorporation of the dynamic arc model leads to erroneous results. Mathematical analysis and field experiments show that natural secondary arc extinguishing in a highly compensated 1150 kV power transmission line can not be reached in a reasonable time, e.g. less than 1 second. It is shown in the paper that this problem can be solved by automatic phase shunting (APS) of the faulted phase.