油纸电容式变压器套管电容心受潮的检测原理与试验研究

Theoretical and Experimental Study on Damping Defect Measurement of Capacitive Core of Transformer's Oil-impregnated-paper Condenser Bushing

由于近年来套管电容心干燥不彻底、介损超标等缺陷发生率较高,严重影响电力设备的安全稳定运行,而且在套管出厂试验、交接及预防性试验中很难发现。针对上述问题,文中分析了变温条件下油纸绝缘的介质损耗特点以及油纸电容式套管的热稳定性,并分别在电容心受潮的主变套管以及未受潮的主变套管上进行套管热稳定过程中的介损测量以及高温条件下的高压介损实验,实验验证了理论分析,同时也能成为一套能有效检测高压套管电容心受潮的无损试验方法。高温下的介损试验更能有效准确的暴露出油纸电容式套管容芯受潮的缺陷,可用于油纸绝缘套管出厂试验。并在此基础上,进一步提出了基于套管热稳定性的在线监测方法。

The faults of incomplete drying and exceeding limit often happen to the capacitive core of transformer＇ s oil-impregnated-paper condenser bushing, which will harm safe and stable operation of electric power equipment. And these faults are usually difficult to be detected in the delivery test, acceptance test and preventive test for the bushing. In this study, the dielectric loss characteristics of the oil-impregnated-paper insulation and the thermal sta- bility of the condenser bushing were analyzed under variable temperature condition. Dielectric loss measurement and high-voltage dielectric loss test at high temperature were conducted for the bushings with damped or dry capaci- tive core, and the results verified the theoretical analysis. This test could become an effective nondestructive test for damping fault of the oil-impregnated-paper insulation for high-voltage bushings. Test at high temperature is more ef- fective for exposing the damping fault compared with the test at ambient temperature, so it can be applied to the de- livery test. In addition, an online monitoring method for high-voltage condenser bushing was proposed based on the thermal stability of the bushing.