Simulation of leader inception from overhead transmission lines under lightning background

Abstract

The judgment of the leader inception is very important in the shielding performance analysis of transmission lines by the leader progression model (LPM). The existing criteria of leader inception and propagation from transmission lines are generally based on the research results from long gap discharges on conductor to plane gaps without considering the lighting background and the operating voltage on the phase conductors. This paper presents a space charge model in the vicinity of high voltage transmission line conductors based on the special electric field distribution under lightning background. Based on the proposed space charge model, a computer program is developed to simulate the streamer-leader process on the conductors. Time-dependent method is then adopted to simulate the inception of continuous upward leader step by step. In the calculation of the electric field in the space charge zone, the operating voltage, the lightning downward leader, the induced charge, the space charges and the incepted upward leaders are considered. Characteristics of leader inception from shielding wires and phase conductors are analyzed. The impact of operating voltage and lightning current amplitude on the leader inception is discussed. The simulation results are compared with that from the existing models. It is discovered that the inception of leaders from shielding wires are easier than from the phase conductors on the high voltage transmission lines. But once the leader is incepted on the phase conductors, the progression of such leader is significantly faster than the leaders from shielding wires.