1998 Volume 118 Issue 4 Pages 364-372
The lightning outage rate is one of the most important factors to design transmission lines. it is very complicated to calculate the lightning outage rate because there are many parameters to be considered such as a lower-footing resistance, a peak value and a waveform of lightning current, a striking angle and so on. The double-circuit outage is the most urgent problem in electric power systems. However, it is difficult to analyze a multiphase flashover of the transmission lines because the flashover on each phase occurs sequentially and the arcing-horn voltage is affected by the other phase flashovers, An analysis using the EMTP shows a sufficient accuracy, but requires a large computation time. Thus, a more convenient and simplified method is desired to estimate the flashover for the parameters.
This paper proposes a calculation method to evaluate a back-flashover outage due to a direct-lightning hit t a tower. The method is based on an integration method and a lumped-parameter circuit theory. The method not only treats an arcing-horn voltage and a flashover time, but also is able to handle nonlinear characteristics such as a nonlinear grounding resistance and the multiphase flashover. Thus, the proposed method is very convenient to investigate a lightning performance.