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Surface charge pattern analysis on HVDC insulators is a difficult task, which requires a comprehensive understanding of the physical mechanisms of surface charging. This paper provides a review on surface charge patterns and related models published within the past 30 years. In addition, based on the field-dependent charging theory, the research differences of various surface charge patterns obtained by previous researchers are explained. Difficulties and future prospects in modeling of surface charging phenomenon are also discussed. This paper may be used as a reference for the analysis of charge accumulation patterns and it would be helpful to researchers to compare and understand charge accumulation results published by earlier researchers. [ABSTRACT FROM AUTHOR]

A theoretical model considering the dynamic change of surface charge accumulation in transient and steady states is proposed. The surface charge accumulation under transient and steady states are simulated using three model spacers with different volume conductivities. The results show that on the convex surface of a spacer, when the volume conductivity is lower than 2 × 10−18 S/m, the hetero-polarity charge accumulated on the spacer surface is dominant, while the homo-polarity charge accumulated on the surface is dominant when the conductivity is higher than 6 × 10−17 S/m. The surface charge density is non-uniformly distributed, and the time duration of the transient process of the surface charge density at different positions on the spacer surface is different, due to the distribution of electric field lines. It is hopefully that the content of this paper can provide reference for the mechanism study of gas-volume interface charge transport and the preparation of HVDC spacers. [ABSTRACT FROM AUTHOR]

The dynamic behavior of surface charging on spacers in DC-GILs can be influenced by multi-factors including the non-uniform distributed electric field as well as the time-varying temperature gradient. In this paper, the time-varying effect of surface charging phenomenon on spacers is studied and a time-varying mathematical model is established, based on the influence of temperature and electric field on the ion mobility at the gas phase and the bulk conductivity in the solid phase. The results verify that the bulk conductivity can be greatly influenced by temperature, which leads to an increase in the surface charge density on the spacer. This allows the surface charge accumulation to stabilize more quickly. However, the ion mobility from the gas phase is less affected by temperature. When the non-uniform distributed electric field changes from 1.3 to 6.4 kV/mm, ion mobility is less influenced and the surface charge density on the spacer varies slightly. In this case, the effects of the non-uniformly distributed electric field in surface charge density variation is much smaller and can be ignored. [ABSTRACT FROM AUTHOR]