SF_(6)气体正极性电晕放电特性仿真研究

Simulation and Study of Positive Corona Characteristics in SF_(6)Gas

为了研究SF_(6)气体正极性电晕放电特性,采用有限元仿真软件COMSOL的流体动力学-化学混合数学模型,对针-板间隙SF_(6)气体正极性电晕放电过程进行了仿真,研究了不同外加电势、间隙距离、初始粒子数密度条件下的电晕放电特性。得到主要结论如下:放电过程可分电流上升、电流下降以及电流趋于稳定3个阶段,电流上升阶段是由于电子崩形成所致;电流下降阶段是由于针尖区域电子数量减少,电离反应减弱,正离子云团远离针电极所致;电流趋于稳定阶段是由于电子崩过程基本结束,正离子云团在远离针尖区域漂移速率减缓所致;脉冲电流上升和下降耗时与外加电势负相关、与间隙距离正相关;脉冲电流峰值及稳定值与外加电势正相关、与针-板间隙距离负相关;针尖粒子数密度由1×10^(9)~1×10^(14)m^(-3)变化时,脉冲电流上升耗时、下降耗时、电流峰值以及电流稳定值与针尖初始粒子数密度关系不大。

In order to study the positive corona discharge characteristics of SF_(6)gas,SF_(6)positive corona is simulated based on the hydrodynamic and chemical hybrid model of COMSOL Multiphysics in this paper.The current characteristics of the corona pulse under different potentials,needle-plane spacing and initial particle density are researched.As a result,the corona can be divided into three stages:the rise stage,the fall stage and the stabilization stage.The rise stage is due to the formation of electron collapse;the fall stage is due to the decrease in the number of electrons in the needle tip area,the ionization reaction weakened,and the positive ions away from the needle electrode;the stabilization stage is due to the fact that the electron collapse process finished basically,and the drift velocity of the positive ions in the area away from the needle tip are slowed down.The time consumption of rising and falling of pulse current is negatively correlated with the applied potential and positively correlated with the needle-plane spacing.The peak current and the stable current are positively correlated with the applied potential and negatively correlated with the needle-plane spacing.When the initial particle density of the needle tip changes from 1×10^(9)m^(-3)to 1×10^(14)m^(-3),the rising time,falling time,peak current and stable current of the pulse current have a negligible relationship with the initial particle density.