Design of a New Busbar for VFTO Suppression and Analysis of the Suppression Effect

Very fast transient overvoltage (VFTO) is characterized by short wavefront time, high amplitude and wide frequency. VFTO poses a threat to the safe operation of power equipment. In order to suppress the harmful effects of VFTO transmission on power equipment, a new type of busbar based on the structure of “inductance + resistance” has been designed, which is called a “damping busbar”. In this study, the equivalent circuit of a damping bus including spurious parameters was developed. These stray parameters are formed between the GIS enclosure and the damping bus, and between the disk insulators and the damping bus. A damping bus simulation model was established based on the equivalent circuit to carry out analysis of the relationship between the structural parameters of the damping bus and the inductance generated by the damping bus. The simulation results showed that the number of turns plays a decisive role in bus inductance, and the relationship between the number of turns and inductance is approximately linear. Comparative analysis of multiple waveforms was carried out before and after the addition of damping buses to the GIS on a 550 kV test rig. The test data showed that the average amplitude of VFTO decreased by 20.36% after the installation of the damping bus, the number of breakdowns decreased by about 66.7%, and there was no obvious high frequency in the measured waveform after installation. In short, the damping busbar had a good suppression effect on the amplitude and frequency of VFTO, and reduced the number of breakdowns. This technique provides a novel solution for VFTO suppression.