Calculation model of lightning induced overvoltage using PSCAD/EMTDC program for overhead distribution lines

Key words:  overhead lines  lightning induced overvoltage  calculation model  soil resistivity  lightning protection

Abstract:

In order to study the lightning induced overvoltage(LIV) and lightning performance of distribution lines, the Agrawal model was converted to modal expression using the similarity transformation, and the expression was analyzed with the method of characteristics. An equivalent calculating circuit of LIV was obtained with the analysis with which a calculating model in PSCAD/EMTDC was proposed and verified for the accuracy of the model. The influences of soil resistivity, surge arrester and coupling ground wire on LIV were also analyzed. The results show that, distribution lines located in high soil resistivity region should be protected with particular emphasis; for low insulation lines, the LIV is dramatically diminished when the soil resistivity is low and arrester installation interval is less than 400 m, or the soil resistivity is high and arrester installation interval is less than 200 m; for high insulation level lines, the arrester installation interval should be less than 400 m when the soil resistivity is high; and lastly the smaller the altitude difference between line conductors and neutral conductor is, the larger the lightning induced voltages decrease.