Lightnings excite isolated high voltage networks to oscillate

Isolated networks are common practice for operating small high voltage networks. The reason for choosing this type of network are the saving of the arc suppressing coils by coexistence of a self-healing grind in case of an earth fault During the starting up of an isolated network several unexpected voltage oscillation phenomena were detected and measured. Investigations have shown that lightning strokes in the area around the high voltage line are the sources of the voltage oscillation. Comparison between the measurement of the voltages and currents of the high voltage line and the lightning detection protocol of the Austrian Lightning and Detection System (ALDIS) show that the lightning causes the voltage oscillation. This paper describes the phenomena based on measurements, the correlation with lightning strokes and will confirm the measurements with simulation examples.