Recommended volt ampere characteristics of MOA in the lightning invasion over-voltage calculation of UHV AC Substation and its influence on simulation results

Abstract

Metal oxide arrester (MOA shortly) is the main measure to protect the over-voltage of lightning invasion wave in UHV AC substation. It directly determines the lightning impulse insulation level of substation equipment and the lightning protection safety of equipment. For the location and quantity of arresters, the standard provisions should be determined by calculation of lightning invasion wave overvoltage. What kind of volt ampere (V-A shortly) characteristic curve being adopted in the simulation model of arrester directly determines its limiting effect on the over-voltage of lightning invasion wave and the configuration scheme of arrester. In this paper, the overvoltage of lightning invasion wave in GIS and HGIS UHV AC substation was simulated by using the electromagnetic transient calculation program (EMTP shortly). The voltage and current waveform characteristics of lightning arrester in the process of lightning inrush wave were statistically analyzed. In the calculation, only the lightning stroke in the near area of 2km approach line which was the most harmful to the substation was considered. The results showed as follows. The time distribution of lightning current wave head passing through the arrester was from 0.26 to 1.53 μs, and the average wave head time was about 1 μs. So the V-A characteristic curve of 1/10 μs is more reasonable than that of 8/20 μs. According to this, this paper gave the V-A characteristic curve of 1/10 μs current waveform which was used in the lightning invasion wave simulation calculation, and gave the calculation results of the safe operation characteristics of the substation when the lightning arrester adopted the V-A characteristic curve of 1/10 μs and 8/20 μs current waveform, and made a comparative analysis of the two results. The research results made a solid foundation for further improving the rationality of the configuration of lightning arresters in substations.