Interference analysis and protection of electronic current transformer caused by disconnect switch operation in GIS

In order to provide the theoretical reference for engineering design and safe operation of integrated electronic current transformer (ECT) in GIS, this paper considers that very fast transient overvoltage (VFTO) caused by disconnect switch operation is the only interference source and the root causes of the electronic current transformer with electromagnetic interference. The inside and outside transient circuits of a GIS substation in Sichuan are established by EMTP. The typical structure of the transformer interval GIS is selected as the analysis object and the reasonably parameters are chosen to establish VFTO and TEV simulation model by using EMTP. The VFTO and TEV occurred at main nodes are calculated. The calculation and research results show that the design and application of GIS integrated electronic current transformer is a system engineering. It needs to consider the overall design of GIS, suppression of VFTO in GIS structure layout, buses, the size of the shell and well-earthing and other factors. Besides the interference protection design of the sensor part and the electronic circuit part of electronic current transformer are suggested.