中文摘要：

电晕放电是输电线路设计和运行中面临的突出问题。电晕放电产生的能量损耗和无线电干扰、可听噪声干扰是线路设计和运行中需要考虑的重要因素。为此，研究了气压湿度等对正直流输电线路电晕起始电压产生的影响。输电导线大多采用单根导线或分裂的钢芯铝绞线，要计算导线电晕起始电压，绞线的表面电场需要得到准确计算。采用一种新的模拟电荷布置方法精确计算绞线表面电场，模拟电荷的布置考虑绞线表面的影响，绞线相比于光滑导线表面场强增大了约40％。利用气体放电理论中计算表面光电子数目的方法计算不同气压湿度下的导线电晕起始电压。结果表明新的模拟电荷布置方法计算出的表面电场和电晕起始电压更精确，避免了表面粗糙系数m的影响，电晕起始电压随气压下降、湿度升高而减小，主要原因分别是有效电离系数增大导致的电离区域的扩大和高场强区域内碰撞电离能力的增强。

英文摘要：

The corona discharge effect is one of important problems in the design and operation of transmission lines. Energy loss, radio interference, and audible noise interference caused by corona discharge should be considered. Consequently, the impacts of air pressure and humidity on onset voltage of positive corona of transmission line were studied. Transmission lines are almost stranded conductors, thus, to calculate the onset voltage of positive corona on stranded conductors, the electric field in the vicinity of stranded conductors should be accurately calculated. The charge simulation method concerned with stranded conductors was introduced to calculate the electric field intensity. The electric field intensity of stranded conductor was 1. 4 times higher than that of smooth conductor. Then the number of photoelectron on the surface of the stranded conductor was adopted to compute the onset voltage of posi tive corona. It is shown that calculated results of the electric field in the vicinity of stranded conductors and the onset voltage of positive corona are accurate, and corona inception voltage decreases as air pressure is lowered or humidity is raised, due to the expansion of the ionization zone and strengthening of collision ionization intensity respectively resulting from the increase of the effective ionization coefficient.