摘要
目前极化-去极化电流(polarization and depolarization current,PDC)法被用来替代频域介电谱(frequency domain spectroscopy,FDS)法获取变压器油纸绝缘在低频下的诊断信息,以实现有效的频域诊断并节省测试时间。为了研究基于PDC法对油纸绝缘的频域诊断,制作了不同热老化程度和不同含水量的油纸绝缘模型,并基于PDC的时频变换分析了其低频损耗特性。油纸绝缘的低频介质损耗因数被分为电导损耗因数(tanδconductance)和总极化损耗因数(tanδtotal-pol)两部分,其中总极化损耗因数包括偶极子极化损耗因数(tanδdipole-pol)和界面极化损耗因数(tanδinterface-pol)。结果表明:随着热老化时间的增加,油纸绝缘模型的tanδconductance曲线和tanδtotal-pol曲线均有所上移;而随着含水量的增加,油纸绝缘模型的tanδconductance曲线大幅上移,tanδtotal-pol也有所增加且tanδinterface-pol增加相比于tanδdipole-pol增加更为明显。这说明热老化同时影响了油纸绝缘的电导损耗和极化损耗;而水分则大幅增强油纸绝缘的电导损耗并使得界面极化损耗也有所增加。最后,通过对比实际变压器低频损耗的分析结果和预防性试验结果证明了利用PDC对油纸绝缘低频损耗特性进行分析的有效性。
To effectively diagnose oil-paper insulation of transformers in frequency domain,the polarization and depolarization current(PDC)method was used to replace the frequency domain spectroscopy(FDS)method in acquiring diagnostic information under low frequency.To research diagnosis for oil-paper insulation in frequency domain based on the PDC method,we prepared oil-paper models with different thermally aging degree and different moisture content,and analyzed the dielectric loss characteristics of them based on time-frequency transformation for PDC.The low-frequency dielectric loss factor is divided into two parts,namely,conductance loss factor(tanδconductance)and total polarization loss factor(tanδtotal-pol).The total polarization loss factor consists of the dipole polarization loss factor(tanδdipole-pol)and the interfacial polarization loss factor(tanδinterface-pol).The results show that,as the thermally aging time increases,the curves of tanδconductance and tanδtotal-pol of the oil-paper models shift upward.As the moisture content increases,the curves of tanδconductance substantially shift upward and tanδtotal-pol also increases.Specially,tanδinterface-pol increases more substantially than tanδdipole-pol for damped oil-paper insulation.The results indicate that thermally aging influences both the conduction loss and the polarization loss of oil-paper insulation,while moisture mainly enhances the conduction loss significantly and the interfacial polarization loss slightly.Finally,the validity of using PDC to analyze the low-frequency loss characteristics of oil-paper insulation was proved by comparing the analysis results of the low-frequency loss characteristics and preventive tests of actual transformers.
作者
周凯
李明志
饶显杰
陈诗佳
ZHOU Kai;LI Mingzhi;RAO Xianjie;CHEN Shijia(College of Electrical Engineering and Information Technology,Sichuan University,Chengdu 610065,China;Skill Training Centre of Sichuan Electric Power Company,Chengdu 611133,China)
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2020年第8期2830-2838,共9页
High Voltage Engineering
基金
中国博士后科学基金(2015T80976).
关键词
极化去极化
介质损耗因数
油纸绝缘
绝缘劣化
绝缘老化诊断
polarization and depolarization
dissipation factor
oil-paper insulation
insulation deterioration
diagnosis of insulation aging