不同气压下N_2~+离子迁移率对直流正电晕放电特性的影响

离子迁移率是高海拔地区电晕放电的关键参数之一,其取值大小对于考虑海拔因素的电晕计算模型具有重要意义,因此有必要研究不同气压条件下离子迁移率的变化对电晕放电的影响。采用5mm棒-板间隙模型,棒电极施以15kV直流电压,板电极接地,并在流体动力学模型的基础上加入9种粒子间化学反应。结果表明,N_2~+离子迁移率的增大会导致电晕头部离子数密度的增加,从而加强对间隙电场的畸变作用,轴向最大场强在接近板电极时会随之减小;N_2~+离子迁移率的增大也会降低电晕平均发展速率;海拔越高N_2~+离子迁移率对电场分布、平均发展速度和离子数密度的影响越明显。研究成果可为输电线路架设等工程实践提供指导。

Effect of N+2 Ion Mobility on Positive DC Corona Characteristics under Different Pressures

Ion mobility is one of the key parameters of corona discharge at high altitude region. The value of the ion mobility is of great significance for the corona calculation model considering the elevation factor. Therefore, it is necessary to study the impact of change of ion mobility on the corona discharge under different atmospheric pressure conditions. Using a 5 mm bar-plate gap model, a rod electrode was applied with 15 kV DC voltage, and the plate electrodes were grounded. Based on the hydrodynamic model, 9 kinds of interparticle chemical reactions were added. The results show that the increase of N+2 ion mobility will increase the ion number density of the corona head, and thus strengthens the distortion effect on the gap electric field. The maximum axial field strength will decrease when approaching the plate electrode. The increase of N+2 ion mobility will also reduce the average development rate of the corona. The higher the elevation is, the more the impact of N+2 ion mobility on the electric field distribution, the average development speed, and the ion number density is obvious. Research results can provide guidance for engineering practice like transmission line erection.