基于放电统计参数动态变化率的油浸芳纶绝缘纸局部放电发展过程研究

Partial Discharge Development Process of Oil-immersed Aramid Paper Based on Dynamic Change Rate of Discharge Statistical Parameters

车载变压器运行环境恶劣,在运行中易出现绝缘缺陷,引发局部放电,损伤油纸绝缘系统,影响列车安全稳定运行。本文根据车载变压器的匝间绝缘结构,使用芳纶绝缘纸设计了三层油纸局部放电模型,在实验室中开展局部放电模拟试验,使用局部放电检测仪检测局部放电信号,并提出局部放电统计参数动态变化率的方法,表征局部放电发展过程。结果表明:油浸芳纶纸的放电相位谱图呈对称分布,放电起始后放电量迅速增加至nC级;根据放电相位谱图及动态变化率可将油浸多层芳纶绝缘纸的放电过程划分为起始、发展、危险和击穿4个阶段;其中放电重复率变化率在放电阶段变化处存在拐点,可用于评估油浸芳纶绝缘纸的局部放电发展过程。

The insulation defects are likely to occur during operation of on-board transformers due to the harsh operating environment,resulting in the appearance of partial discharges and the degradation of oil-paper insulation,which might affect the safe and stable operation of trains.Therefore,according to the inter-turn insulation structure of on-board transformer,a three-layer oil-paper partial discharge model was designed by using aramid paper,and partial discharge simulation tests were carried out in lab.The partial discharge signal was recorded by partial discharge detector,and the dynamic change rate of discharge statistical parameters was proposed to characterize the development process of partial discharge.The results show that the discharge phase spectrograph of oilimmersed aramid insulating paper is symmetrically distributed,and the discharge magnitude rapidly increases to nC level after initial discharge.The discharge process of oil-immersed aramid insulating paper can be divided into four stages,including starting stages,development stages,dangerous stages,and breakdown stages according to the discharge phase spectrograph and dynamic change rate of discharge statistical parameters.Besides,the dynamic change rate of discharge repetition rate has an inflection point during discharge process,which can be used to evaluate the partial discharge development process of oil-immersed aramid insulating paper.