Study On Radiation Transport Characteristics Of Eco-Friendly SF₆ Replacement Arcs

In order to reduce greenhouse gas emissions,it has become a consensus among academia and industry to find eco-friendly SF₆ replacements.At present,the eco-friendly SF₆replacements are mostly used in the field of insulation,but the research on their arc extinguishing performance is not sufficient and is still in the exploratory stage.An excellent interrupting medium should quickly cool the arc,and radiation as the main form of arc energy transport plays a key role in the interrupting process.Therefore,this paper adopts a combination of simulation and experiment to study the radiation transport characteristics of eco-friendly SF₆replacements in the arc extinguishing process,which can lay a theoretical foundation for the engineering application of eco-friendly arc extinguishing gases and promote the green and low-carbon transformation of high-voltage switchgears in china.The eco-friendly replacements studied in this paper includes SF₆-CO₂、SF₆-N₂、SF₆-CF₄、SF₆-Air、C₄F₇N-CO₂、C₄F₇N-N₂、C₅F₁₀O-CO₂and C₅F₁₀O-N₂,with a wide range of gases and the ratios between different gas components to be considered.In order to reduce the calculation cost and improve the research efficiency,this paper firstly establishes a rapid evaluation system of arc extinguishing performance based on the one-dimensional arc model and Boltzmann equation,and proposes the average recovery rate R_avgand the average recovery degree D_avg as comprehensive evaluation parameters to realize the rapid evaluation of various gas arc extinguishing performance.According to the above evaluation of arc extinguishing performance,SF₆-N₂,C₄F₇N-N₂ and C₄F₇N-CO₂ are screened as objects for further research.Secondly,by coupling multi-physical field equations,including Navier-Stokes equations,Maxwell equations and turbulence equations,a two-dimensional arc model based on the net radiation model is established for eco-friendly SF₆ replacements in this paper.The multi-physical field distributions such as temperature,radiation energy and electric potential of eco-friendly SF₆ replacement arcs are obtained.The radiation transport characteristics of the eco-friendly SF₆ replacement arcs during the contact opening process are investigated,and the effects of current magnitude and mixing ratios on the arc shape,temperature,radiation energy and Volt-Ampere characteristics are investigated.It is found that due to the distribution of arc radiation energy along the X axis,the eco-friendly SF₆ replacement arcs is gourd-shaped.As the current increases,the arc radiation energy,temperature and volume increase.With the increase of arc extinguishing gas content,the temperature distribution range of arcs decreases under the action of radial Lorentz force,and the arc area gradually shrinks.The arc exhibits negative volt-ampere characteristic at low current（20～50A）and positive volt-ampere characteristic at high current（70～100A）.Finally,this paper designs and establishes an arc experiment platform to study the radiation transport characteristics of the selected gaseous arcs.In the experiment,the high-speed camera and spectrometer are used to capture the arc shape images and collect the arc spectral information respectively.The experimental results show that there is randomness in the arc development,but the arc shape is basically similar to the simulation results.The arc brightness is heightened with the increase of current,indicating that the radiation transport energy is gradually enhanced.In addition,considering that the arc temperature is the macro indication of radiation transport characteristics,this paper also measures the temperature of eco-friendly replacement arcs based on the spectral information.The results show that Although the measured arc temperatures are slightly lower than the simulation results,the evolution trend is consistent.According to the measured temperatures,it can be speculated that the arc radiation energy in the experiment is in the same order of magnitude as the simulation results,which also verifies the effectiveness of the simulation model in this paper.