Improve the electrogeometric model by the analysis results of leader propagation model for transmission lines

Lightning shielding failure probability efficiency evaluation is important for transmission line design, especially for ultra-high voltage level. Traditional electrogeometric model (EGM) is not suitable for ultra-high voltage transmission lines because it neglects the upward leaders incepting from ground wires or power lines, while the lightning propagation model (LPM) works. The main contribution of this paper is to improve EGM by the analysis results of LPM. Besides adopting the concept of striking distance from traditional EGM, the concepts of upward leader length and its propagation angle, which describe the propagation process of upward leaders, were introduced. The formulae of improved EGM for a typical kind of 1000 kV transmission towers were obtained by numerical fitting of the calculation results of LPM. Results show the improved EGM coincides with LPM.