Abstract
An increase in transient enclosure voltage can threaten the personal safety of workers and the normal operation of secondary equipment and may cause discharge between the flanges of gas insulated switchgear (GIS) enclosures. This study considered the spark–discharge fault between GIS enclosure flanges of a 500-kV nuclear power plant in China when the disconnect switch is operated in the background. The dynamic arc model during the operation of the disconnect switch was improved in this study, and the equivalent calculation model of transient enclosure voltage (TEV) caused by very fast transient overvoltage generated during the operation of the disconnect switch was established using the electromagnetic transient program ATP-EMTP. Suppression measures of the discharge phenomena were also discussed. The results demonstrated that the transient enclosure voltage caused by the operation of the disconnect switch can reach 75 kV in the most severe case, which causes discharge between the flanges. Reducing the residual charge on the island side of the disconnect switch, installing a metal oxide arrester, and reducing the inductance of the ground wire have different inhibitory effects on this discharge phenomenon, but they all have their limitations. The most simple and effective control measure is to use a short joint between two flanges. The study conclusions can be used as reference for preventing such discharge phenomena.
Highlights
Gas insulated switchgear (GIS) is used increasingly at all voltage levels because of its safety, reliability, small floor area, and less work on overhaul
Since the GIS equipment parameters were not given in the literature [18], the selection was carried out according to the empirical parameters, and the improved dynamic arc model built in this paper is used in the process of generating arc by operating disconnecting switch
According to the results, adding metal oxide arresters (MOAs) between flanges can effectively suppress the potential difference caused by transient enclosure voltage (TEV) between them, and the lower the operating voltage, the greater the suppression effect
Summary
Gas insulated switchgear (GIS) is used increasingly at all voltage levels because of its safety, reliability, small floor area, and less work on overhaul. Lin et al [7], [8] combined a GIS shell model with an internal transient model by using phase mode transformation and studied the influence of different operation modes and grounding modes on TEV amplitude. Few studies have focused on TEV generated by multiple pulse superpositions with different amplitudes and waveforms in actual operation, which leads to a large deviation between the calculated results and the actual situation. The calculation results in this paper have great reference value for preventing this type of phenomenon
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