Study on Coupling of Very Fast Transients to Secondary Cable via a Test Platform

Electromagnetic disturbance can be induced on the secondary cables by very fast transients generated during switching operation in the gas-insulated switchgear (GIS) substation. Usually, the secondary equipment that is fixed on GIS pipe or placed in the local control cabinet is connected by the cables. Disturbance voltages coupling to the terminal ports of the cable may cause malfunction of the equipment. To study the coupling mechanism of the disturbances, some experiments are carried out based on a test platform established in the laboratory. Through comparing the data that come from the lab experiments, the measurement of some GIS substations, and the IEC61000-4-18 standard, respectively, it is illustrated that the parameters of the disturbance generated on this platform are consistent with those measured in GIS. Then, an equivalent circuit model with transmission line network is proposed and the simulated waveforms are agreed with the experimental results.