复合绝缘子直流电场下的水滴运动及覆冰特性

The icing of transmission line insulators threatens the stable operation of the power system, and the icing morphology and rate of insulators are the key parameters for predicting the development of flashover. In order to accurately simulate the insulator icing, this paper explores the influence of the DC electric field on the insulator icing from the perspective of water droplet movement and capture. Taking a composite insulator as a sample, a mathematical model of water droplet movement is established based on the principles of fluid mechanics and electromagnetic fields, and the trajectory deviation rate of water droplets on the insulator surface due to the electric field force is calculated. Based on this, the local collision coefficient β_1 distribution of water droplets at the edge of the insulator umbrella skirt and on the mandrel with and without an electric field is calculated. The results show that under the conditions of a small wind speed and a small water droplet radius, the water droplet trajectory deviation under the action of the electric field is the largest, and the percentage increase in the β_1 value at the insulator mandrel exceeds 15%. Icing tests on composite insulators with and without electricity were carried out in an artificial climate chamber. The results show that during the dry growth icing with a small water droplet radius, the percentage increase in the icing rate due to the electric field reaches 30%, and a rougher icing surface can be caused at the same time. However, the influence on the wet growth icing rate with a large water droplet radius is relatively small, mainly resulting in a curved ice ridge morphology.

输电线路绝缘子覆冰威胁着电力系统运行稳定,而绝缘子覆冰形态及速率是预测其闪络发展的关键参数。为准确模拟绝缘子覆冰,该文从水滴运动及捕获角度探究了直流电场对绝缘子覆冰的影响。以复合绝缘子为样品,基于流体力学及电磁场原理建立水滴运动数学模型,计算了水滴在绝缘子表面因为电场力作用发生的轨迹偏移率,以此为基础,计算了有、无电场下绝缘子伞裙边缘及芯棒处的水滴局部碰撞系数β_1分布,结果显示:小风速小水滴半径下,电场作用下的水滴轨迹偏移最大,且对绝缘子芯棒处的β_1值提高百分比超过15%。在人工气候室内对复合绝缘子进行了带电和不带电覆冰试验。结果表明:小水滴半径下的干增长覆冰时,电场对覆冰速率的提高百分比达30%,同时可造成更加粗糙的覆冰表面,但对于大水滴半径下的湿增长覆冰速率影响较小,主要造成弯曲生长的冰棱形态。