直流负极性下雨滴对导线电晕特性的影响

Influence of Corona Characteristics of Water Drops on Smooth Conductor under Negative DC Voltage

高压直流输电线路电晕会带来严重的电磁环境问题。导线电晕已经成为影响特高压直流输电线路结构和建设费用的决定性因素。随中国电网的不断发展,特高压直流输电线路电晕问题开始受到人们的关注。在降雨过程中,导线表面会形成大量的雨滴,雨滴的存在严重影响导线的电晕特性。为了研究大气条件对直流输电线路电晕特性的影响,笔者利用电晕笼,研究了导线表面雨滴的电晕放电过程,以及导线表面附有雨雾和饱和雨滴的起晕电压和电晕电流特性。针对自然界中降雨电导率的差异,研究了不同电导率的雨雾和雨滴对电晕放电的影响。结果表明,导线上雨滴的电晕放电是一个伴随着雨滴变形、喷射以及雨滴周围空气电离的复杂过程。当导线表面附有饱和雨滴和雨雾时,起晕电压分别约降低到无雨滴时起晕电压的25%和40%。在降雨电导率范围内,雨滴电导率变化对电晕放电影响不明显。

Corona phenomena on HVDC transmission lines will cause electromagnetic environment problems. UHVDC transmission line corona has become an important factor which affects the configuration and cost of construction of UHVDC transmission lines. With the development of power grid construction, corona problem of UHVDC transmission lines becomes a research focus. In the rainfall process, a lot of water drops will formed on the wire surface, which can change corona characteristics of transmission lines obviously. To study the influence of water drops on corona characteristics of DC transmission lines, the corona discharge process has investigated in a corona cage with one water drop attached to the surface of the high voltage conductor. The corona inception voltage and corona current characteristics of the saturated water drops or mist on the conductor surface were studied including the effect of the change of the water conductivity. The result shows that corona discharge with one water drop on the surface of the conductor is a complex process including the deformation and ejection of small water drops, the ionization of the air around the tip of the water drop. When the conductor is attached with saturated water drops or mist, the corona inception voltage decreases to about 25% or 40% compared with that of smooth conductor. In the range of rainfall conductivity, the c.hange of the water drop conductivity has less effect on the corona discharge characteristics.