An improved method for HV substation lightning performance estimation

The paper presents a statistical approach to the highvoltage substation lightning performance estimation. The method involves the monthly distribution of the lightning discharges to the lines, determined according to the l i e geometry and thunder activity, as well as the monthly probability distribution of the substation configurations. The mean time between failure of the power transformer insulations is estimated for a 400 kV / 110 kV transformer substation. The paper provides the analysis of the results obtained for various dispositions, number and place of positioning the surge arresters, as well as the power transformer basic insulation level. The improved procedure of the lightning performance estimation can contribute to a more economical substation design.