负极性同轴圆柱电极电晕建模研究与计算

Modelling and Calculation of the Negative DC Corona Plasma in Coaxial Cylindrical Electrode

电晕特性是特高压直流输电线路设计的关键技术问题之一。电晕放电物理过程复杂,影响因素多,基于电晕放电物理过程建立数值模型进行计算是研究电晕问题的有效手段。电晕流体模型在电晕等离子的仿真计算中得到广泛的应用。大部分电晕流体模型的计算中使用Kaptzov假设作为边界条件,没有考虑二次电子发射机制,并且当电晕电流较大时,没有充分考虑的电子扩散、电荷复合和空间光电离等因素的影响。文中基于简化的电晕等离子体流体模型,进一步考虑电子扩散、电荷复合、空间光电离和二次电子发射机制提出完整模型,采用4阶龙格—库塔法对同轴圆柱模型的负极性电晕进行了仿真计算,分析了不同因素对计算结果的影响,探究了负极性电晕等离子体电荷密度和电晕场的分布规律。考虑二次电子发射对结果影响最大,但在180kV时差别也不超过2%。

Corona is one of the critical technical problems in ultra-high voltage direct current （UHVDC）transmis- sion. Corona discharge is a complex physical process and has various influencing factors. Establishing numerical model based on the physical process of corona discharge is an effective means to research the corona problem. Corona fluid model has been widely used in the simulation calculation of corona plasma. However, most of calculations in corona fluid model using Kaptzov assumption as boundary condition do not have considering on secondary electron emission mechanism. Moreover, the effects of electron diffusion, charge recombination and photoionization were not taken a full consideration when corona current was larger. In this paper, a comprehensive model based on the simplified corona plasma fluid model has been proposed, which furtherly considers electron diffusion, charge recombination, space photoionization and secondary electron emission mechanism. Meanwhile, the negative DC corona plasma in coaxial cylindrical electrode has been calculated by the Runge-Kutta method. Finally, the impacts of different fac- tors on the calculation result have been analyzed and the distribution regularities of negative DC corona plasma and corona field have been observed. Secondary electron emission mechanism has larger effect on the result than the other factors but the difference is less than 2% under 180 kV.