重复脉冲电压下油纸的局部放电损伤对其电气性能影响的实验研究

Experimental Study on Influence of Oil-immersed Paper Damage Caused by Partial Discharge on Its Electrical Performance Under Repetitive Pulse Voltage

研究了重复脉冲电压下油纸的局部放电损伤对其电气性能的影响。分别采用材料分析手段和电气测量手段,分析了脉冲电压放电过程中油纸的形貌、产物和微观结构等损伤特性,以及电导、极化、损耗和击穿等电气性能;对比分析了油纸在洁净处理前后的微观结构及产物对其电气性能的影响。结果表明:重复脉冲电压下,油纸放电损伤后的产物主要为醛类或羧酸类物质,损伤产物在绝缘表面呈辐射状分布且引导电树枝走向;脉冲电压边沿突变(du/dt→0)产生的瞬时冲击电应力加剧了纤维素分子碎片的形成,脉冲电压长时延平顶区为分子碎片的重结晶提供了充裕时间;微观结构变化和放电产物生成对油纸电气性能影响的效果相反,但放电产物是决定电气性能的主导因素。

This study investigates the influence of oil-immersed paper damage caused by partial discharge on its electrical performance under repetitive pulse voltage.Material analysis and electrical measurement measures are used respectively to analyze such damage characteristics of oil-immersed paper as morphologies,products and micro structures during pulse voltage discharge.The electrical performance such as conductivity,polarization,loss and breakdown has also been studied.The influence of micro structure of oil-immersed paper and its product on its elec-trical performance before and after cleaning is compared and analyzed.The results show that under repetitive pulse voltage,damage products caused by partial discharge of oil-immersed paper are mainly aldehydes or carboxylic ac-ids,damage products are distributed radially on insulation surface and guide development trend of electric tree.The transient impulse voltage stress generated due to the edge mutation(du/dt→0)of pulse voltage intensifies formation of cellulose molecular fragments,and the long-delay flat-top region of pulse voltage provides sufficient time for recrys-tallization of molecular fragments.Micro structure variation and discharge product generation have opposite effects on electrical performance of oil-immersed paper,but discharge product is the dominant factor to determine electrical properties.