硅橡胶中局部放电发展与电树枝生长的关系研究

Study on the Relationship Between Partial Discharge Development and Electrical Tree Growth in Silicone Rubber

研究硅橡胶中电树枝化微观物理过程与局部放电宏观表征之间的关系,能够为基于局部放电严重程度在线评估电缆中间接头的绝缘状态提供理论依据。制备了带有缺陷的硅橡胶切片试品,在逐级升压过程中实时测量了硅橡胶绝缘劣化起始直至击穿全过程中的电树枝照片和局部放电信号,生成了电树枝面积和单位时间内局部放电能量随时间的变化曲线,阐述了两条曲线之间的对应关系。基于电树枝面积曲线的变化规律,将电树枝生长全过程划分为引发及生长、滞长、快速生长共计3个阶段,讨论了各阶段电树枝的生长模式;基于局部放电能量的发展变化规律,将局部放电发展全过程划分为5个阶段,得到了各阶段局部放电相位特征谱图,提取了灰度图空穴面积和局部放电相位宽度作为表征局部放电严重程度的特征量。研究结果表明,电树枝面积曲线和局部放电能量曲线的发展趋势具有高度的一致性,电树枝生长的3个阶段分别对应于局部放电发展的1-2阶段、3阶段以及4-5阶段,从而建立了硅橡胶劣化微观物理过程和局部放电宏观表征之间的关系,为电缆中间接头绝缘状态的在线评估奠定了基础。

Study on the relationship between microphysical processes of electrical tree and macro characterization of PD in silicone rubber, can provide a theoretical basis of cable joints’ insulation condition online assessment based on PD severity. In this paper, the silicone rubber test sample with defect was made;and the electrical tree photos and PD signals were observed and measured during the deterioration process of the test sample;the time curves of electrical tree area and PD energy per unit time were obtained; the relationship between the two curves was expounded. Based on the change of electrical tree area, the development process of electrical tree was divided into three stages： growth, slow growth and rapid growth. The growth pattern of the electrical tree in every stage was discussed. The development of PD was divided into five stages according to the trend of PD energy. For each stage, the phase characteristic spectrograms were got;the cavity in PD gray images, and PD phase width were extracted to evaluate the severity of PD. The results show that, there was a highly consistency between the electrical tree curve and the PD curve. The three growth stages of electrical tree corresponded to the stage 1-2, stage 3 and stage 4-5 of PD development respectively. Thus, the relationship between electrical tree growth and PD development has been established, which laid the foundation for online assessment of the cable joint insulation condition..