Influence of starting voltage waveform on time sequence to restart DC transmission lines

Abstract

Based on experiments and calculations, this paper describes the influence of the time constant of the dc starting voltage on the no‐voltage time required for successful restarting and the time required to complete the restarting. (1) The 300‐kV‐class dc tension insulator assembly tested in this study was composed of disk‐type insulator units used for ac transmission lines. The insulation recovery characteristics of the dc tension insulator assembly after dc arc extinctions of 400 and 4000 A were obtained for the switching impulse voltage and simulated dc starting voltage. The results show that both methods obtained the same minimum values for the required no‐voltage time. Thus, we verified this method's validity in calculating the minimum value of the no‐voltage time required for successful restarting based on the insulation recovery characteristics obtained by the switching impulse voltage. (2) Based on the insulation recovery characteristics obtained by the switching impulse voltage after arc extinction, we calculated the relationships between the required no‐voltage time and restarting completion time versus the time constant of the dc starting voltage. As the rising time constant of the dc starting voltage increased, the required no‐voltage time decreased and the restarting completion time increased. It was shown that reducing the rising time constant of the dc starting voltage was an effective measure to shorten the restarting completion time after the arc extinction. © 2000 Scripta Technica, Electr Eng Jpn, 133(4): 63–70, 2000