中文摘要：

覆冰过程中沿绝缘子串形成的未桥接冰棱和桥接冰柱是造成融冰期绝缘子串发生闪络的主要因素。为此,根据融冰物理过程,研究了冰棱相变过程中水滴喷射对未桥接冰棱闪络的影响。研究发现：水滴喷射过程缩短了冰板间距,改变了冰棱前端的电场分布,是诱发冰板间隙电弧的重要原因。未桥接冰棱受耐受电压值影响,其闪络过程存在沿冰面放电和冰内放电两种形式。桥接冰柱的初始电弧通常出现在冰柱内部气隙处,其融冰闪络路径沿冰柱内部形成贯穿通道。试验结果表明：桥接冰柱发生闪络需要更多的融冰能量来形成贯通通道,而完成击穿过程,因此桥接冰柱的闪络电压值较未桥接冰棱略高。110 kV全尺寸玻璃绝缘子覆冰闪络试验进一步证明,融冰时液滴喷射会形成沿冰棱和水滴路径的闪络通道。综合以上结论认为,融冰滴水是导致未桥接冰棱较桥接冰柱更易发生闪络的重要因素。

英文摘要：

Bridged and non-bridged icicles formed along insulator strings are the main reasons leading to ice flashover during ice melting periods. Therefore, based on melting physics, we analyzed droplet ejection and its impact on non-bridged icicles through experiments. According to our observation, droplet ejection shortens air gap and distorts the electrical field distribution in the gap, which is a main cause of partial arcs and consequent flashover. There were two kind of flashover patterns of non-bridged icicles depended on the applied voltage, including the surface discharge along icicle and the inner partial discharge. As for bridged icicles, partial discharges or arcs occur from air gaps inside; they elongate forward to penetrate through the whole bridged icicle. Experimental results show that more energy is required for bridged icicles to form penetrated channels for flashover; hence bridged icicles have flashover voltage higher than that of non-bridged icicles. A 110 kV full-scale insulator test further proved that flashover path was formed along icicle surface, gap and droplets due to the droplet ejection during ice melting process. It is concluded that droplet ejection is a critical reason to that fact that non-bridged icicles can have flashover more easily than bridged icicles.