TEM-delayモデルによる鉄塔-送電線系雷サージ応答の検証

抄録

A back-flashover due to a lightning strike to the top of a transmission tower or its ground wires can result in the power outage. The occurrence rate and seriousness of the back-flashover should be estimated for existing or planned transmission lines for lightning risk management of power systems. This paper presents a modeling method of crossarms in a Transverse Electro-Magnetic (TEM) delay tower model, which considers a non-TEM characteristic of the tower. The voltages generated across the insulator strings due to a lightning strike to the tower top are discussed based on the analysis results by the finite-difference time-domain method, the TEM-delay model, and the multistory tower model, which has been widely used, with referencing surge experimental results reported in the past. Then back-flashovers of a 77-kV transmission system are analyzed using the proposed and conventional circuit models, and these results are discussed with referencing a measured back-flashover reported in the past. Based on the above analyses and discussions, this paper shows that the voltages across the insulator strings have been underestimated by the conventional model, and shows the applicability of the TEM-delay model to lightning surge analysis in high-voltage transmission systems.