Analysis of Stable Inception Criterion for Upward Leader of Transmission Lines under Negative Lightning

The inception process and stable development criterion of upward leader are the key to examine how well transmission lines protect against lightning. Based on the theory of leader discharge, this essay developed a simulation model of upward leader of transmission lines under negative lightning, and analyzed the upward leader development procedure under different circumstance. The findings indicate that there is a critical value of the space charge in the initial streamer region when a stable upward leader manifests around the conductor. The critical value is affected by the radius of the conductor, and is unrelated to the conductor height, operating voltage and lightning parameters. Thus, the critical space charge criterion of the initial streamer region for the stable inception of the upward leader in the transmission lines was proposed. The results derived using the criterion were in line with the observational findings of the ongoing artificial lightning test, proving the validity of the criterion.