中文摘要：

导线起始电晕电压是输电线路设计、运行中需要考虑的重要问题,在高海拔地区这个问题更加突出。由于极性效应,对于同一电极结构,负极性要先于正极性产生起始电晕。为此,对绞线负极性起始电晕特性进行了分析,采用绞线电场强度E的计算方法,计算了不同E/p值下空气中的碰撞电离系数α、附着系数η。采用相应起始电晕判据,计算了不同海拔高度H下LGJ-300/25绞线起始电晕电压。在武汉（H=23m）、格尔木（H=2829m）、纳赤台（H=3800m）开展实测。将试验结果和计算结果进行对比,二者符合较好。分析结果表明,在输电线路工作地区,随着海拔高度H上升、气压p下降,绞线起始电晕电压呈线性下降趋势,海拔每升高1000m（气压下降9.47kPa）,则绞线负极性起始电晕电压下降约8%。

英文摘要：

It＇s important to assure conductor＇s corona onset voltage in design and operation of transmission line,especially at high altitude areas.Because of polarity effect,negative corona onset voltage is lower than the positive one,with the same electrode structure.Consequently,the negative corona onset voltage of stranded conductors at different altitudes was analyzed.The electric field strength Ecalculation method of stranded conductor was adopted,the ionization coefficientαand electron attachment coefficientηin different E/pranges were obtained,and a corona onset criterion was applied to calculate negative DC corona onset voltages of LGJ-300/25stranded conductors at different altitudes H.Moreover,at Wuhan（H=23m）,Golmud（H=2829m）,and Nachitai（H=3800m）,corona onset characteristics were tested,and the calculation results were in good agreeement with the test results.The results show that,for transmission line,the air pressure pdecreases as altitude Hrises,and the corona onset voltage of strand conductor decreases linearly,the negative corona onset voltage decreases by 8%approximately as altitude increases by 1000m（air pressure pdecreases by 9.47kPa）.