自然条件下输电线路导线覆冰增长特性

输电线路导线覆冰严重威胁着电网安全运行.导线覆冰过程复杂,影响因素众多,对其覆冰增长规律的准确掌握是建立并优化导线覆冰数值计算模型的基础.从自然覆冰试验出发,依托雪峰山自然覆冰试验基地对不同种类的导线进行了自然覆冰观测试验,研究了导线直径、导线表面处理情况、覆冰类型及导线扭转对导线覆冰增长过程的影响.通过导线表面水滴碰撞系数的计算分析了不同直径导线覆冰的差异性.研究结果表明:自然环境条件下,风速对导线雾凇覆冰冰形起决定性作用,覆冰主要在导线迎风面(横向迎风侧)累积,而背风侧和纵向覆冰较少.覆冰厚度随时间非线性增长,导线直径越小,覆冰厚度增长越快.导线扭转使得导线背风侧向迎风侧转变,覆冰厚度增长速率加快.雨凇覆冰时,除迎风侧翼型覆冰外,导线下方易冻结形成冰棱,使得冰形结构更为复杂.

Characteristics of icing on transmission lines under natural conditions

The icing of transmission lines seriously threatens the safety of power grid. The icing process of transmission lines is complicated and involves many influential factors. The accurate understanding of the law of icing is the basis for the establishment and optimization of an icing numerical model. Different kinds of conductors were tested under natural icing conditions on Xuefeng Mountain Natural Icing Test Base. The effects of conductor diameter, conductor surface treatment, icing type and torsion on icing process were studied. The characteristics of icing on conductors with different diameters were analyzed by calculating the water droplet collision efficiency. The results show that under the natural environment, the wind velocity was the key factor which determined the rime shape on transmission lines. Meanwhile, the icing thickness increased nonlinearly with time. The smaller the conductor diameter, the faster the icing thickness increased. The conductor torsion made the leeward side of conductor turn to the windward side, which increased the icing rate. When the icing type became glaze, in addition to the windward wing icing, more icicles were likely formed under a conductor. As a result, the ice structure became more complex.