In order to improve the stability and reliability of high voltage direct current (HVDC) transmission lines in cold regions, this article investigated the corona discharges and the icicle growth characteristics on outdoor insulators under DC voltages. The experiments were conducted at CIGELE laboratory at University of Quebec. The simulation model of corona discharges and the theoretical model of icicle growth were established. The dynamic process and interactive characteristics between the icicle growth and corona discharges under different HVDC voltages were obtained. The results showed that the discharge activity was strong and the cooling effect of ionic air was weak under negative DC voltage, resulting in a large number of bubbles inside the icicle. More negative ions were produced under negative DC voltage, which enhanced the polarisation of water droplets, leading to a greater density of ice beads outside the icicles. In addition, the longest icicles of each insulator under high humidity could bridge the shed gap. The accumulated charge and leakage current were higher under negative DC voltage, as well as the corona discharge at the top of the icicles lasted longer. Therefore, the negative DC corona discharge more significantly inhibited the growth of the icicle, resulting in a slower growth rate of the icicles.

中文翻译：

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高压直流户外绝缘子积冰过程中冰柱生长与电晕放电的动态交互特性

为了提高寒冷地区高压直流输电线路的稳定性和可靠性，本文研究了直流电压下户外绝缘子的电晕放电和冰柱生长特性。实验在魁北克大学 CIGELE 实验室进行。建立了电晕放电模拟模型和冰柱生长理论模型。获得了不同高压直流电压下冰柱生长与电晕放电的动态过程和交互特征。结果表明，负直流电压下放电活性较强，离子空气的冷却作用较弱，导致冰柱内部产生大量气泡。在负直流电压下产生更多的负离子，这增强了水滴的极化，导致冰柱外的冰珠密度更大。此外，高湿度下每个绝缘子的最长冰柱可以弥补伞裙间隙。负直流电压下累积电荷和漏电流较高，冰柱顶部电晕放电持续时间较长。因此，负直流电晕放电更显着地抑制冰柱的生长，导致冰柱的生长速度变慢。