基于扩展Debye模型的变压器油纸绝缘老化特征量研究

Ageing Characteristic Quantities of Oil-Paper Insulation for Transformers Based on Extended Debye Model

为了提取表征油纸绝缘老化状态的新特征量,将时域介电响应技术应用于变压器油纸绝缘老化状态的无损评估,并在深入研究了不同老化状态对油纸绝缘时域介电特性影响的基础上,首先分析了油纸绝缘样品等效扩展Debye模型参数随热老化状态变化的规律,然后提取了四组可用于表征油纸绝缘老化状态的特征参量,并建立了特征参量与绝缘老化状态之间的量化关系。研究表明:扩展Debye模型等效电路参数对油纸绝缘老化状态的反映比较敏感,最小和最大时间常数分支的R、C参数均可以反映绝缘纸的老化状态;最大时间常数分支的参数Rmax和最小时间常数分支的参数Cmin与绝缘纸聚合度存在线性拟合关系,而最小时间常数分支的参数Rmin和最大时间常数分支的参数Cmax与绝缘纸聚合度具有指数函数关系;文中提取的特征量可应用于油纸绝缘的老化状态评估。

In order to extract new characteristic parameters to realize the non-destructive diagnosis of aging state of transformer oil-paper insulation by time domain dielectric response technology, the influence of the aging degree on time-domain dielectric property of oil-paper insulation is investigated. The extended Debye model for oil-paper insulation is further introduced to analyze the influences of thermal degree aging on its parameters. Then four groups of characteristic parameters are extracted to reflect the aging state of the oil-paper insulation. The quantitative relationship between the characteristic parameters and the aging state thus has been established. The test results show that the parameters of the extended Debye model are quite sensitive to the aging state. The parameters of the smallest and the largest time constant branches are both able to characterize the aging state of the insulating pressboards. An obvious exponential rule can be observed between parameters Rmin, Cmax andthe degree of polymerization（DP） of the insulation paper, while the parameters R Cmin exhibit an evident linear rules with DP. The extracted characteristic parameters in this paper can be used for the aging assessment of the oil-paper insulation.