油纸绝缘频域介电谱解释方法研究

Explanation Study of Frequency-domain Dielectric Spectroscopy for Oil-paper Insulation System

为了探索频域介电谱测试结果的解释方法,提升其应用于油纸复合绝缘状态无损检测效果,在深入研究频域介电响应理论的基础上,首先在实验室内构建了油纸绝缘频域介电谱试验平台,然后分析了电导及极化损耗的机制及特性,重点讨论了复介电常数与电场频率之间的关系,提取了典型损耗特性规律,并建立了基于电导及极化损耗模型的频域介电谱理论解释方法。研究表明:复介电常数谱在低频段的特征主要因电导损耗作用所致,可用Dyre模型解释;在高频段的特征主要是因极化损耗作用所致,可用H-N模型解释;而中频段特征则是因电导及极化损耗共同作用所致,可用两种理论模型联合解释。通过该方法可获得复介电常数重构曲线,其与频域介电谱实测曲线具有良好的一致性。所提出的频域介电谱解释方法依据FDS测试结果对油浸纸板复介电常数谱进行分析与拟合,分别获得了电导为主、极化为主的损耗与电场频率之间的统计函数关系,可进一步应用于介电响应特征参数提取,从而为油纸绝缘状态定量评估奠定一定的理论基础。

In order to explore the explanation of frequency-domain dielectric spectroscopy（FDS） and to improve the application to nondestructive diagnosis of insulating state for oil-paper insulation, the frequency domain dielectric response theory is studied further in this paper. Firstly, FDS measurement system for oil-paper insulation is established in the lab. Secondly, the mechanism and characteristics of conductivity loss and polarization loss are analyzed respectively. The classical loss characteristics of oil-paper insulation are outlined by a systematic analysis of the relationship between complex dielectric constant and frequency. And then a theoretical explanation for FDS is introduced based on conductivity loss and polarization loss. The test results show that at low frequencies, the characteristics of complex dielectric frequency spectra are mainly influenced by conductivity loss, which can be explained by Dyre model. At high frequencies, the characteristics are mainly influenced by polarization loss which can be explained by H-N model. In addition, the characteristics at middle frequencies are the results of conductivity and polarization loss. The reconstructed curve obtained by this method accords with the measured curve well. The presented explanation method in this paper is used to analyze and fit the complex dielectric frequency spectra of oil-paper insulation based on the test results of FDS. And the statistical function relationships either between frequency and polarization or between frequency and conductivity are obtained, which can be used to extract characteristic parameters of dielectric response. These build up the theoretical foundation for the quantitative assessment of insulating state.