非旋转对称高压直流电缆的电-热场分析

Electro-thermal Field Analysis of Non-rotationally Symmetric HVDC Cable

利用有限元法建立了单芯高压直流电缆的非旋转对称模型,考虑到电场、温度等物理场的耦合影响,分析了含缺陷电缆在不同温度梯度下电场强度的暂态和稳态分布特征,考察了空间电荷层对电场强度分布的影响。结果表明:相比于正常电缆模型,非旋转对称电缆缆芯上方的电场强度减小,下方的电场强度增大,且下方的电场更易发生翻转。当绝缘层存在水树缺陷时,缺陷与绝缘界面产生的电荷层导致电场强度激增;随着温度梯度和加压时间的增加,电场强度与空间电荷均呈减小趋势。

A non-rotationally symmetric model of single core high voltage direct current(HVDC) cable was built by finite element method. Considering the coupling influence of physical field such as electric field and temperature field, the transient and steady state distribution characteristics of electric field intensity of cable with defect under different temperature were analyzed, and the effect of space charge layer on the electric field intensity was investigated. The results show that compared with the normal cable model, the electric field intensity above the cable core of non-rotationally symmetric cable decreases,while the electric field intensity below the cable core increase and it is more likely to reverse. When there are water tree defects in the insulation layer, the charge layer, generated by the interface of defect and cable insulation, make the electric field intensity enhance sharply. With the increase of temperature gradient and voltage applied time, the electric field intensity and space charge decrease.