基于去极化电流特征参数分析法的油纸绝缘老化评估

摘要

The variation discipline on depolarization current characteristic parameters was investi-gated based on the extended debye model.The parameters were included relaxation contribution factor,time constant,polarization resistance,and polarization capacitor.A new parameter called relaxation energy which can be used to diagnose the aging stages of oil-paper insulations was first-ly proposed.The parameter was able to reflect the process of electric energy accumulation and re-lease in each relaxation mechanism of oil-paper insulations adequately,and the process was highly related to the aging stages.The field measurement results showed that the relaxation contribution factor,the relaxation energy and the polarization capacitor increased with the increasing of insula-tion aging degree,whereas,the time constant and the polarization capacitor decreased.The relax-ation energy of small time constant branch and large time constant branch reflected the aging de-gree of insulating oil and insulating paper individually.%以扩展德拜极化电路模型为基础，研究不同老化程度下去极化电流特征参数(弛豫贡献系数、时间常数、极化电阻、极化电容)的变化规律。提出一种可用于评估油纸绝缘老化状态的参数--弛豫能量，该参数可以充分地反映油纸绝缘系统各弛豫机构电能积累和释放的过程。现场实测数据分析结果表明：随着设备绝缘老化程度的加剧，弛豫贡献系数增加、时间常数减小、极化电阻减小、极化电容增大及弛豫能量增加；小时间常数支路和大时间常数支路的弛豫能量分别反映绝缘油和绝缘纸的老化状态。