Observation and analysis of lightning surges at substations connected with UHV designed transmission lines

On UHV-class transmission lines with sections of 500-kV class insulation, lightning observations have been made to study the generation and the propagation of overvoltage into substations. Voltages and currents were recorded at substations and at junction-tower footings during three flashovers on the UHV system. These observations were then matched to EMTP calculations by adjusting the average soil resistivity and the average conductor height in the propagation model. It is also found that the attenuation due to corona of voltages was small because it is expected to be minimal for 8-conductor bundles.