Capacitance and electric field analysis of UHVDC SF6 gas insulated wall bushing support insulator

This paper aims to investigate the effect of the number of support insulators on the electric field and capacitance distribution in 1100kV DC SF6 gas insulated wall bushing. The double-layer shielding scheme is a common technique used in SF6 gas insulated wall bushing to equalize the electric field., in which the support insulators connect the floating potential electrode and the grounded electrode. A detailed model of SF6 gas insulated wall bushing is established and its impact on the electric field distribution in the bushing is analyzed by varying the number of support insulators. The result indicates that as the number of support insulators increases., the potential of the floating potential electrode decreases., the surface field strength of the shielding cover decreases., and the external field strength of the sheath does not change significantly. Meanwhile., the capacitance matrix in the bushing is simulated and calculated. The results show that as the number of supporting insulators increases., the capacitance between the floating potential electrode and the grounded electrode increases. This is considered to be the direct reason of the increase in potential of the floating potential electrode.