配电电缆绝缘劣化的极化去极化电流特性仿真

为实现对6 kV交联聚乙烯(XLPE)电缆绝缘状态的可靠检测,基于德拜扩展模型建立了整体受潮、局部受潮、绝缘老化、含水树枝电缆的仿真模型,采用极化-去极化电流法(polarization-depolarization current,PDC)对电缆绝缘状态进行诊断,研究电缆在不同绝缘状态下PDC特性变化规律。结果表明:电缆受潮较严重时,电压电流呈现明显的非线性关系,绝缘电阻下降速率更快;水树枝程度越深,极化去极化电流初始值越大,电缆绝缘性能越差。

Simulation Analysis of Depolarizing Current Characteristics of Power Distribution Cable Insulation Deterioration

In order to realize the reliable detection of the insulation state of 6kV cross-linked polyethylene cable, the lumped parameter models of power cable with several kinds of defects such as moisture, aging and water-tree are established based on Debye expansion model in this paper. The polarization-depolarization current (PDC) method is adopted to diagnose the insulation status of cable, and the variation characteristics of PDC under different insulation states are investigated. The results show that the voltage and current curves present obvious nonlinear relationship when the cable is affected by moisture. The initial value of polarization depolarization current increases with the increase of water branch degree,which represents the worse insulation performance of the cable.