Analysis of shielding failure flashover rates for HV transmission lines
Abstract
This paper will present an analysis of the expected number of outages of a HV transmission line, which are the result of direct lightning strikes to phase conductors. It should be noted that the aforementioned analysis is an integral part of the design process of the HV transmission line tower head (i.e. positioning of the protective wire in relation to the phase conductors). The analysis of the number of outages of a HV transmission line, which are the result of a flashover on its insulation (shielding failure flashover rate – SFFOR), will be carried out using the so-called electrogeometric model of lightning strike development. In addition, when determining the number of SFFOR of a high-voltage transmission line, the statistical distribution of lightning current amplitudes will be taken into account, as well as the keraunic level of the area along which the observed transmission line extends. Finally, the presented analysis of the number of outages of a HV transmission line due to direct lightning strikes to the phase conductor will be applied to a characteristic example of a 110 kV overhead line of the “Jela” type.
