多应力条件下电缆附件局部放电的演变过程

Evolution of partial discharge in cable accessories under multi-stress conditions

电缆附件界面是多层复合介质绝缘结构,在温度、气压、电场等物理条件下都易产生局部放电(partial discharge,PD)。为了研究多种应力条件下局部放电的演变过程,在10 kV电缆终端中设计典型刀痕缺陷,并在实验室搭建“冷热负荷-工频电压-冲击电压”多应力条件下的协同老化平台,利用该平台对电缆进行老化试验,利用工频局放测试平台检测不同老化时间下电缆终端的局部放电。利用波动法对不同老化阶段下的电缆附件局放信号进行消噪,并采用阈值窗提取消噪后的局放信号中的PD脉冲,构建电缆附件局放相位分布(phase resolved partial discharge,PRPD)谱图。实验结果表明:多应力条件下,在不同老化程度下,刀痕缺陷电缆附件的局放经历三个“起伏”击穿,放电幅值存在多段式“增-减”的变化趋势。

The cable accessory interface is a multilayer composite dielectric insulation structure,which is prone to partial discharge(PD)under physical conditions such as temperature,air pressure,and electric field.In order to study the evolution process of partial discharge under various stress conditions,a typical knife mark defect is designed in the 10kV cable terminal,and a collaborative aging platform under the multi-stress conditions of"cold and heat load-power frequency voltage-impulse voltage"is built in the laboratory.The platform is used to perform aging test on the cable,and the power frequency partial discharge test platform is used to detect the partial discharge of the cable terminal under different aging periods.The wave method is used to de-noise the partial discharge signals of the cable accessories under different aging stages,and the PD pulses in the partial discharge signals after the de-noising are extracted by the threshold window lift to construct the PRPD spectrum of the partial discharge signals of the cable accessories.The experimental results show that,under the condition of multiple stresses,under different aging degrees,the partial discharge of the knife mark defect cable accessory experiences three"ups and downs"breakdowns,and the discharge amplitude has a multi-stage"increase-decrease"variation trend.