中文摘要：

为了揭示覆冰状态对融冰及其闪络过程的影响,结合现场覆冰形貌观测,提取出4种典型覆冰形态,包括未桥接冰棱、桥接冰柱及其两种双层组合方式,并对各典型覆冰形貌下的闪络特性开展试验研究,分析了融冰过程中冰棱尖端水滴喷射对电场分布的影响。从融冰耐压时间分布特性和恒压耐受时闪络概率分布的角度,研究了不同覆冰形态下覆冰水电导率、冰棱长度、空隙与冰棱长度的不同组合对融冰闪络特性的影响。覆冰水电导率与冰棱长度通过改变融冰过程中剩余冰层电阻来影响覆冰闪络过程。试验中发现,电导率由150μS/cm上升至750μS/cm,闪络电压下降了33%;冰棱长度由6cm下降至4cm,闪络电压降低了10%。空隙与冰棱长度的不同组合对融冰闪络影响显著,其中冰柱模型由于内部电弧烧蚀会造成冰棱融断而难以发生闪络。在冰棱-冰柱的双层组合模型中,由于冰柱融化需要汲取额外的能量,冰棱-冰柱模型的最低闪络电压较冰棱-冰棱模型提高了14%。研究表明,未桥接冰棱在融冰液滴喷射过程中,其冰尖处易出现电场集中,与桥接冰柱相比,可在更低的耐受电压下诱发融冰闪络。

英文摘要：

Aiming at reflecting the effect of ice morphology on the melting process and its flashover, according to the ice morphology captured in field, we extracted four kinds of typical ice morphology including bridged icicles, non-bridged icicles, and their combination. Flashover experiments under different morphology were carried out during the melting period. According to the electrical field simulation, the effect of droplet ejection was analyzed and compared. Moreover, from the perspective of voltage-time distribution and flashover probability, we mainly concerned with the effect of impact factors, including applied water conductivity, icicle length, combination of air gap and icicle length, and compared their flashover characters. The experiment results show that the applied water conductivity and icicle length will affect the residue ice layer resistance; Flashover voltage decreases by 33% and 10%, respectively, while conductivity increases from 150 μS/cm to 750 μS/cm and length declines from 6 cm to 4 cm. Bridged icicle absorbs extra power for ice melting, leading to flashover increase. It is verified in the double ice layer experiment that flashover voltage increases by 14% when bridge icicle exists. It can be concluded that non-bridged icicle is more vulnerable to suffer ice flashover compared to bridged icicle because of electrical field concentration at the icicle tip, leading to relatively lower withstand voltage.