Study on 330kV GIS Transient Enclosure Voltage Caused by Disconnecting Switch Operation

In Gas-Insulated Substation (GIS), the Transient Enclosure Voltage (TEV) would threaten the reliability of secondary devices. Studying the propagation law of TEV can provide reference for suppression method of TEV. In this paper, field measurement and theoretical simulation were taken to study the TEV of a 330kV GIS. At first, the TEV caused by operation of disconnecting switch was measured and analyzed. Then, this paper built a simulating model based on electrical main connection to obtain the TEV under the maximum residual voltage. Finally, a method was proposed to reduce the TEV. The simulation results showed that reducing the grounding inductance can reduce the TEV effectively. The study shows that: (1) The maximum voltage of TEV can reach to 4.9kV, the transient time is among 100ms to 160ms, and the main frequency ranged from 11MHz to 35MHz. the maximum value of TEV does not always appear at the enclosure under out-line bushing in an operation, which is related to the TEV propagation path. (2) The TEV generated by the disconnecting switch near out-line bushing is much more serious than the TEV generated near the bus. The TEV generated during opening operation is more serious than the TEV generated during closing. (3) Reducing the equivalent inductance of grounding can reduce the value of TEV. When the equivalent inductance decrease 40%, the maximum voltage can be reduced by 21%. So reducing the equivalent inductance may be a possible effective way to reduce the value of TEV.