基于迁移管法气压对氮气正电晕放电离子迁移率的影响

摘要

The ion mobility in low gas pressure is a key parameter for corona discharge of power transmission line in high altitude area. Meanwhile, nitrogen as the main reaction gas in positive corona discharge, its existing value of the ion mobility takes no consideration of gas pressure. Actually, the measurements of ion mobility in different gas pressures have great significance to establish the ion current and corona loss calculation models. A needle-ring corona discharge experiment platform is designed and set up, which can simulate different gas pressures. What's more, the execution of the ion gate is improved from off-on-off to off-on, thus the waveforms with higher amplitudes of the ion could be gained. Thanks to the designed platform, the measured ion mobility of pure nitrogen under normal atmospheric condition is 1.113cm2V−1S−1. Besides, the positive nitrogen ion mobility at gas pressure of 101.19~44.52kPa is measured. The experimental results indicate that the ion mobility decreases nonlinearly with the increasing of gas pressure and has a certain trend of saturation. Finally, an index correction method is put forward.%低气压下离子迁移率是高海拔地区输电线路导线电晕放电的关键参数之一，同时氮气作为正电晕放电参与反应的主要气体，目前均作为常量对待，其测量结果对于建立考虑海拔因素的离子流、电晕损失等计算模型具有重要意义，因此对不同气压下氮气正离子迁移率的测量显得尤为重要。在已有研究的基础上，自主设计了可模拟不同氮气气压条件下离子迁移率测量平台，并将离子门的动作方式由关闭—导通—关闭改进为关闭—导通，从而得到幅值尽可能大的离子流波形。利用此平台测量得到大气条件下纯氮气环境离子的迁移率为1.113cm2V−1S−1，并通过试验研究了气压在101.19～44.52kPa范围内氮气环境离子迁移率变化情况，研究发现氮气正离子迁移率随气压增大呈非线性减小且具有一定的饱和趋势，最后提出了一种氮气正离子迁移率随气压变化的指数修正方法。