Ma, G.-M.; Zhou, H.-Y.; Li, C.-R.; Jiang, J.; Chen, X.-W., "Designing epoxy insulators in SF6-filled DC-GIL with simulations of ionic conduction and surface charging," in Dielectrics and Electrical Insulation, IEEE Transactions on , vol.22, no.6, pp.3312-3320, December 2015（SCI IF: 1.228）

doi: 10.1109/TDEI.2015.005031

The problem of surface charge accumulation on gas-insulator interface is one of the critical

factors for the development of DC Gas Insulated transmission Lines (GIL). In order to solve

this problem, researchers have proposed a variety of mathematical models in which the

volume conductivity of SF6 was assumed to be constant for calculating the distribution of

surface charge. However, the conductivity of SF6 was inconstant, affected by electric field

strength. In this paper, a gas model is developed, taking into account the generation,

recombination and motion of charge carriers in SF6 of DC-GIL. The surface charge density

and the electric field distribution on the insulator surface under DC voltage were simulated.

Afterwards, the electric conduction through the volume of the insulator was proved to be the

dominating accumulation mechanism. In order to improve the insulation performance, the

influence of practical insulator shape on the electric field distribution in DC-GIL was studied.

Three different shapes of insulator which were disc insulator, conical insulator and obtuse

conical insulator were introduced and compared. The simulation results indicate the obtuse

conical insulator was the most suitable configuration for DC-GIL.