Influence of Cloud-to-ground Lightning With Long Continuous Current on Fault Restart Characteristic of 500 kV DC Transmission Line

Abstract

For the problem of DC transmission lines blocking caused by Cloud-to-ground (C-G) lightning with long continuous current, a transient calculation model of lightning striking line is built considering the long continuous current and protective module. The protection operation characteristics and fault restart process of 500 kV DC line are analyzed due to long continuous current. The influence of long continuous current amplitude and duration on the fault restart process is studied. The actual control and protection strategies is used to simulate the whole process of DC line blocking caused by C-G lightning with long continuous current. Results show that the long continuous current has little influence on the response characteristics of travelling wave protection criteria under lightning strike disturbance and lightning strike failure. When the amplitude of long continuous current exceeds 470 A, the fault arc can burn stably. If the duration of long continuous current exceeds the deionization time, the line will fail to restart. The repeated restart tests show that the line can be successfully restarted only if the long continuous current is over in the deionization stage (before the voltage begins to rise). Appropriately extending the deionization time is helpful for the successful improvement of the line restarts under the action of C-G lightning with long continuous current.