油纸绝缘频域介电谱的修正Cole-Cole模型特征参量提取及水分含量评估方法

Characteristic Parameters Extracted From Modified Cole-Cole Model and Moisture Content Assessment Methods Study on Frequency-Domain Dielectric Spectroscopy of Oil-Paper Insulation

为了应用频域介电谱技术实现变压器油纸绝缘水分含量的定量评估,在实验室中制备了不同水分含量的油纸绝缘样品,分析了水分含量对样品介电特性的影响规律,同时引入修正Cole-Cole模型提取了油纸绝缘频域介电特征参量,研究了水分含量对这些特征参量的影响规律。结果表明,水分含量的变化会对油浸绝缘纸板样品的频域介电特性产生较大影响,采用修正Cole-Cole模型提取的频域介电特征参量中,?弛豫时间常数??及直流电导率?dc会随着油浸绝缘纸板水分含量的增加分别明显变小和增大;对参量水分含量m.c.的初步拟合显示,??和?dc与m.c之间分别呈现指数和线性关系,可考虑作为定量评估油纸绝缘水分含量的特征参量。

In order to apply the technology of frequency-domain dielectric spectroscopy（FDS） to quantitatively assess moisture contents of oil-paper insulation for transformer, the oil paper insulation samples with different moisture contents were prepared under laboratory conditions. After analyzing the influence of moisture content on frequency-domain dielectric property of oil-paper insulation samples, this paper introduced the modified Cole-Cole model to extract the frequency-domain dielectric parameters. The effects of moisture content on frequency-domain dielectric characteristic parameters are studied, and the new quantitative relationships between the moisture content and the characteristic parameters were proposed. The results show that the moisture contents heavily affect the frequency-domain dielectric property of oil-paper insulation samples. Among the characteristic parameters extracted from modified Cole-Cole model, α relaxing time constant てα decreases and conductivity σdc increases respectively with the moisture contents m.c. increasing. The fitting results primarily show that the relationship between てα and m.c. is exponential, and the relationship between σ dc and m.c. is linear. Thus てα and σdc can be taken as two characteristics for moisture content estimation.