Lightning overvoltage protection of the Paddock 362-145 kV gas-insulated substation

Backflashovers close to the Paddock 362-145 kV gas-insulated substation (GIS) have been analyzed with the electromagnetic transient program (EMPT) using a frequency-dependent multiconductor system. The severities of the lightning stroke currents were based on recent recordings in the eastern United States. The effects of corona attenuation and distortion were accounted for using a shunt linear model approach. Turn-up effects of both line insulator flashover voltages and surge arrester protective characteristics were based on manufacturer's volt-time curves. Wave-shaping effects of substation capacitances were modeling details in determining the overvoltages inside the GIS due to close backflashovers, which are caused by lightning strokes with varying intensity. These results are aimed at better evaluation of lighting protection requirements for GIS protected by metal-oxide surge arresters.<
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