Lightning protection of the 110 kV substation at the wind park Ivan Sedlo against transients caused by direct lightning strikes into connected overhead line

This paper deals with the lightning protection of 110 kV substation at the wind park Ivan Sedlo against transients caused by direct lightning strikes into connected 110 kV overhead line. Lightning protection level (LPL) I as per standard IEC 62305-1 is selected for this substation to reduce probability of equipment failure to low level. Calculations are done in the EMTP-ATP software. Three critical scenarios are analysed: shielding failure at the connected 110 kV overhead line, lightning strike to the top of first tower in front of the substation and lightning strike to the top of gantry tower at the entrance to the substation. It is presented that LPL I for analysed configuration of substation can be achieved by installing two sets of surge arresters. First set of surge arresters is installed in the transmission line bay, while second set of surge arresters is installed in the transformer bay. Transferred lightning transients through the power transformer are also calculated. It is presented that one additional set of surge arresters is necessary at the 30 kV side of the power transformer, to protected it against transferred lightning transients. Energy duty of all three sets of surge arresters is calculated. At the 110 kV voltage level energy stress of surge arresters is significant and strongly depends on the substation grounding resistance value. Estimated energy stress of set of surge arresters at the 30 kV voltage level is very low.