内部气压下电缆电树枝不同生长阶段的局部放电统计参量研究

Study on Partial Discharge Statistical Parameters of Cable at Different Growth Stage of Electrical Trees Under Internal Gas Pressure

交联聚乙烯(XLPE)电缆绝缘电热老化产生的气体会在绝缘层或绝缘材料微孔内产生局部高气压,为了研究内部气压作用下XLPE电缆绝缘的老化特征,分别以XLPE短电缆和电缆绝缘层切片为试验样品,搭建了试验系统,研究了局部气压作用在绝缘层或绝缘材料微孔内时的局部放电及其绝缘老化特征,并采用局部放电矩特征分析局部气压作用下XLPE电缆局部放电特征参量与绝缘老化程度之间的关系,探讨将其应用于交联聚乙烯电缆绝缘老化评估的可能性。结果表明:局部高气压使电树枝通道内局部放电加剧,绝缘老化加速;微孔内的气压相较于绝缘层气压对电树枝内局部放电的促进作用更加明显;最大放电量相位分布H_(qmax)(φ)谱图的偏斜度Sk、峭度K_u和放电次数相位分布H_n(φ)谱图的放电相位分布可作为评估XLPE中电树枝发展阶段的标准。

Crosslinked polyethylene（XLPE） would generate gas during electrical-thermal ageing process,and the gas would produce partial air pressure in the insulating layer or microvoids of insulating material. In order to study the ageing characteristics of XLPE cable insulation under partial air pressure,XLPE short cable and slice of cable insulating layer were used as test samples, and a test system was set up. The partial discharge and insulation ageing features with partial air pressure acting on the insulating layer or microvoids of insulating material were studied, and the relationship between partial discharge characteristic parameters and ageing degree of insulation was analyzed by moment feature, and then the parameters were used to assess the ageing degree of XLPE insulation. The results show that the partial air pressure makes the partial discharge in electrical trees intensify and accelerates the ageing of insulation. The air pressure in microvoids has bigger promoting effect on the partial discharge than that in insulating layer. The skewness（S_k）, steepness（K_u）, and partial discharge phase distribution H_n（φ） spectrogram can be used as criteria to evaluate the develop stage of electrical trees in XLPE.