| SF6 is a very excellent insulated medium and is widely used in electric power industry. The thorough research of SF6 and their mixtures can further open the applications field, providing the theory basis and technical support to exploit new gas dielectricThis dissertation makes numerical analysis of SF6/N2 and their mixtures for discharge process, establishes fluid model of SF6/N2 and their mixtures gas discharge by adopting particles continuity equation together with coupling Poisson equations. The N2 fluid model are composed of the electrons, positive ions continuity equations coupled with the Poisson equation, the SF6 and their mixtures are composed of the electrons, positive ions and negative ions continuity equations coupled with the Poisson equation. This model is solved by applying finite element method. The simulation of two-dimensional discharge process in SF6/N2 and their mixtures includes ionizatioin, attachment, recombination, diffusion and so on.The gas discharge process in SF6/N2 and their mixtures are simulated and the simulation results are analyzed. The results show that the gas discharge process includes three stages, which are electron avalanche discharge, electron avalanche discharge translate streamer discharge and steamer discharge. The dielectric strength of a high SF6 content gas mixtures is higher than a low one.In addition, this dissertation also analyse the influence of different position of initial seed electronic and number in gas discharge process.The research results of this dissertation can help knowing and understanding the mechanism of gas discharge in SF6/N2 and their mixtures. It not only clear described the influence of the gas discharge process of different initial seeds, but also made the gas discharge process visualization which included all kinds of charged particles and plasma channel dynamic behaviors of the distribution of internal electric, forming the foundation for the further research and development of new insulation gas medium. |
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