绝缘气隙放电对高压电缆的电学和热学性能的影响研究

Study on the Influence of Insulation Air Gap Discharge on Electrical and Thermal Performance of High Voltage Cable

摘要: 高压电缆受制造工艺、拉伸和弯曲的影响，绝缘介质容易出现开裂现象而形成裂纹气隙，从而降低高压电缆绝缘材料的绝缘性能。本文首先利用ANSYS有限元仿真软件，建立高压电缆二维电–热耦合模型，并进行了模型验证；其次研究了绝缘介质中存在裂纹气隙时的电场变化规律，以及裂纹气隙局部放电所引起的温度分布变化。结果表明：1) 存在气隙的情况下，气隙中的电场强度增大，而绝缘屏蔽层与气隙和导体屏蔽之间的绝缘介质的电场强度减小；2) 随着气隙长度增加，气隙内部的电场越大，当气隙长度小于1 mm时，不易引起气隙局部放电，当气隙长度大于1 mm时，更易引起气隙局部放电；3) 气隙持续放电引起的绝缘温度升可达87.8℃。该论文研究成果可为高压电缆绝缘设计和状态监测提供参考。

Abstract: The high-voltage cable is affected by the stretching, bending and manufacturing processes. The insulating medium is prone to cracking and forms a crack air gap, thereby reducing the insulation properties of the high-voltage cable insulation material. In this paper, the ANSYS finite element simulation software is used to establish the two-dimensional electro-thermal coupling model of the high-voltage cable, and the model verification is carried out. Secondly, the electric field distribution and temperature distribution law in the presence of air gap in the insulation medium are studied. The results are as follows: 1) the electric field strength in the air gap increases, and the electric field strength in the insulation shield and in the insulation medium between the air gap and conductor screen decreases. 2) As the gap length increases, the larger the electric field is. When the air gap length is less than 1 mm, it is not easy to cause air gap discharge. When the air gap length is more than 1 mm, the air gap discharge is more likely to occur. 3) The rise of insulation temperature caused by the continuous discharge of the air gap can reach 87.8˚C. The research results of the paper can provide reference for the insulation design and condition monitoring of high-voltage cables.