Modelling of the inhibition effect of thin-wire ultra-corona on upward leader and its application on lightning protection in high-voltage transmission lines

Under the induction of thundercloud charges or lightning leader, ultra-corona occurs on the surface of thin wire-clad conductors, which could not only inhibit the formation of streamers to prevent the development of upward leaders but also change the potential distribution in the surrounding space. Taking advantage of these characteristics, the upward leader from a power conductor can be suppressed by wrapping thin wires around ground wires. The inhibition mechanism of ultra-corona on the upward leader has been analysed and its characteristics and development laws have been studied by constructing ultra-corona model under thundercloud conditions. A model for studying the inhibition effect of ultra-corona on the upward leader by combining the ultra-corona model and leader progression model is presented, and a detailed overall analysis of its influence on lightning protection performance on a 500 kV transmission line is conducted. According to the simulation results, the shielding failure width reduces with the thin wire-clad ground wires, and the attraction of the upward leader from power conductor on lightning leader is weakened. Therefore, the probability of lightning strikes is reduced, and lightning protection of lines is improved. Finally, two influential factors on the thin wire-applied transmission lines are discussed.