中文摘要：

聚丙烯薄膜在拉伸、收卷、分切等生产过程中以及高压储能电容器的芯子卷绕过程中由于现有技术条件的限制会受到各种不均匀机械应力的作用,这些非均匀应力会造成薄膜上的皱折、电弱点甚至硬伤,即绝缘缺陷。为研究这些缺陷的存在对高压储能电容器的工作可靠性的影响,运用电子拉伸试验机搭建了对聚丙烯薄膜施加可变机械应力的试验模型,并借助高灵敏度的直流局部放电测试系统采集聚丙烯薄膜在承受不同机械应力作用下的直流局部放电特征量,包括起始放电电压、放电次数、平均放电量、最大放电量;从机械应力导致薄膜介质内部出现电荷陷阱的机理分析了局放特征量的变化以及发展趋势。试验分析结果表明机械应力的作用会导致聚丙烯薄膜介质内部微孔增大以及分子链的断裂,介质内部电场严重畸变,从而导致直流局部放电性能的恶化。因此应大力提升电容器的生产和制作工艺,减少不均匀机械应力对薄膜的作用。

英文摘要：

Due to the technical limitations, polypropylene film could encounter many kinds of uneven mechanical stress when in the producted process like stretching, winging, splitting and convoluting the roll of high-voltage energy storage capacitor , the stress could cause wrinkles, electric weakness and even mechanical damage,in another words, insulative defects. The existence of defects may seriously affect the dependability of capacitor. In this paper, we built the model which can imposed variable mechanical stress to pp film based on electronic tensile testing machine and collected the DC partial discharge characteristic quantity of pp film under the condition of different mechanical stress by using high sensitivity direct current partial discharge test system, which including： inception voltage, discharge time, average discharge magnitude, the maximum discharge magnitude. Then, we analyzed the pd characteristic quantity and its development trend by the mechanism of mechanical stress cause the appearance of charge trap in the film dielectric. The test result indicated that mechanical stress could deteriorated the dcpd performance. The test result indicated that mechanical stress could lead to the augment of microporous and rupture of molecular chain. Inside polypropylene film, electric field of internal dielectric distorted resulting in the deterioration of dcpd performance. So improving production technics of capacitor is very helpful for decreasing the effect of uneven mechanical stress on the film.