Emerging simulation technologies for obtaining the parameters of insulation materials in HVDC-GIL subjected to transition field

In this paper, we compared the differences in the charge accumulation for two different models about conductivity: one in which the conductivity value of the spacer is invariant with time(steady-state conductivity, Model I) and one in which the conductivity value can vary dynamically with time(dynamic conductivity, Model II). The time for the potential distribution to reach a stable state was 8078 s in Model I and 7932 s in Model II. After the charge accumulation reached saturation, the charges migrated to the middle of the spacer under the applied electric field. The maximum tangential field strength was 2.56 × 10 ¹ V/m in Model I and 2.84 × 10 ⁶ V/m in Model II. During the simulation, the amount of charge in the gas side was less than 10 ⁻⁵ C/m ³ , which is much smaller than the charge density in the spacer. The mechanism underlying the charge accumulation phenomenon is the differences in the conductivity value distribution caused by a time-varying temperature gradient field. This paper can provide a more precise theoretical base for the selection and modification of HVDC-GIL spacer.