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Abstract <p>Partial discharges induced by free metal particles impair the insulation performance of high-voltage electrical equipment. Owing to its environmental benefits, cost-effectiveness, and excellent dielectric properties, the SF<sub>6</sub>/CO<sub>2</sub> gas mixture has emerged as a promising alternative for gas-insulated applications. This study establishes a two-dimensional plasma fluid model, utilizing the finite element method to self-consistently couple the current and electrostatic fields for simulating the discharge of millimeter-sized particles in an SF<sub>6</sub>/CO<sub>2</sub> mixture at 220 kV. The results indicate that as the proportion of SF<sub>6</sub> increases from 10 to 30%, the streamer propagation velocity decreases and the breakdown time prolongs. The streamer head exhibits a sharp rise in electric field strength and electron density. This indicates that SF<sub>6</sub>’s strong electronegativity suppresses electron avalanche development, thereby promoting the accumulation of space charge, which in turn leads to more pronounced electric field distortion. Analysis of ion distribution shows a decrease in <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\({\text{CO}}_{2}^{ + }\)</EquationSource> <!--PlasPhys2560435Qi-m1--> </InlineEquation> density, while the densities of <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\({\text{SF}}_{6}^{ - }\)</EquationSource> <!--PlasPhys2560435Qi-m2--> </InlineEquation> and <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\({\text{SF}}_{5}^{ - }\)</EquationSource> <!--PlasPhys2560435Qi-m3--> </InlineEquation> increase, indicating a shift in the discharge mechanism from being dominated by CO<sub>2</sub> ionization to a synergistic mechanism dominated by SF<sub>6</sub> adsorption and ionization. This study achieves real-time solving of the floating potential of metal particles through multi-physics coupling and systematically elucidates the physical mechanisms of streamer initiation by particles in mixed gases with different ratios, providing a theoretical basis for the formulation of eco-friendly insulating gas mixtures and engineering insulation design.</p>

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Numerical Simulation of Streamer Discharge Characteristics Induced by Free Metal Particles in SF6/CO2 Gas Mixture

  • 期刊论文

  • 发表日期：

    2026年4月1日

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  • Q. Bing,
  • T. Fuyou,
  • L. Chang,
  • W. Hui

摘要

Abstract

Partial discharges induced by free metal particles impair the insulation performance of high-voltage electrical equipment. Owing to its environmental benefits, cost-effectiveness, and excellent dielectric properties, the SF6/CO2 gas mixture has emerged as a promising alternative for gas-insulated applications. This study establishes a two-dimensional plasma fluid model, utilizing the finite element method to self-consistently couple the current and electrostatic fields for simulating the discharge of millimeter-sized particles in an SF6/CO2 mixture at 220 kV. The results indicate that as the proportion of SF6 increases from 10 to 30%, the streamer propagation velocity decreases and the breakdown time prolongs. The streamer head exhibits a sharp rise in electric field strength and electron density. This indicates that SF6’s strong electronegativity suppresses electron avalanche development, thereby promoting the accumulation of space charge, which in turn leads to more pronounced electric field distortion. Analysis of ion distribution shows a decrease in \({\text{CO}}_{2}^{ + }\) density, while the densities of \({\text{SF}}_{6}^{ - }\) and \({\text{SF}}_{5}^{ - }\) increase, indicating a shift in the discharge mechanism from being dominated by CO2 ionization to a synergistic mechanism dominated by SF6 adsorption and ionization. This study achieves real-time solving of the floating potential of metal particles through multi-physics coupling and systematically elucidates the physical mechanisms of streamer initiation by particles in mixed gases with different ratios, providing a theoretical basis for the formulation of eco-friendly insulating gas mixtures and engineering insulation design.