Analysis of Lightning-attractive Areas Around High-voltage Direct Current Transmission Line

Abstract

This article studies attractive areas around high-voltage direct current transmission lines due to downward lightning leader presence. The lightning-attractive areas are drawn for power conductors and shielding wires separately to distinguish the shielding failure area. An electromagnetic model is constructed to draw the attractive areas of the high-voltage direct current transmission lines. The transmission line conductors and the downward lightning leader are modeled by using the charge simulation method. Different cases of surrounding conditions, such as lightning slope, ground slope, and wind, are studied for the same downward lightning current. The attractive areas are affected by considering the high-voltage direct current transmission line voltage. As the downward lightning leader charge is negative, the attractive area around the high-voltage direct current transmission line power conductors increases around positive pole subconductors and decreases around negative pole subconductors. The high-voltage direct current transmission line shielding the failure area of the studied cases is increased or decreased due to the surrounding conditions.

Estimation of Lightning Striking Distance to Horizontal Conductor

“…This electric field intensity is necessary to break down this air gap. In previous work [24], a lateral striking distance occurred when the voltage of cylindrical gap around horizontal conductor reaches the breakdown voltage of this gap. An equation of r s = aI b h c , then exponential coefficient was estimated to consider voltage effect.…”

“…In this paper, the charge decaying distribution along the stepped leader was assumed to be exponentially of a negative charge as [23][24]…”

“…The length of n finite sections was e m (e (n+1) -e n ). The starting distance of the semi-infinite line charge d s =e m (Na+1) , where m is a constant and is chosen to be 1.84 [24][25].…”

“…2. These point charges are recommended in order to increase the boundary and check points at intersections of the horizontal conductor with X-Z plane, and also, due to the presence of downward lightning leader in X-Z plane [24][25]. The assumed factious charges had N r N a +N r unknown charges.…”

“…Assuming a histogram of the amplitude of lightning currents to a flat ground is available, and that it consists of K discrete current values, the log 10 (P ek )=0.05-I k /74 would be the probability of current I k in China, where the ground flash density is assumed to be 0.015 [23][24]. The number of lightning strikes to different horizontal conductors and lightning stroke of a negative charge are calculated by using the electro-geometric model in section I1, and based on the previous assumptions.…”