采用修正Cole-Cole模型提取油纸绝缘频域介电谱的特征参量方法

Application of Modified Cole-Cole Model to Extract Characteristics of Frequency Dielectric Spectroscopy of Oil-paper Insulation

为了定量描述变压器油纸绝缘频域介电谱(frequency domain spectroscopy,FDS)随温度、水分、老化程度等绝缘状态的变化关系,引入了修正Cole-Cole模型研究油纸绝缘的FDS特性,提出采用该模型参量作为油纸绝缘FDS的特征参量,以反映其绝缘性能,并给出了模型的初始值设定方法及优化目标函数。在不同温度下采用三电极测量了油纸绝缘试品的频域介电谱特性,提取了模型的参量并分析其变化规律。结果表明,在10-3～103 Hz频率范围,可以采用单弛豫时间常数的修正Cole-Cole模型来描述油纸绝缘的频域介电谱,该模型将频域介电响应分解为弛豫、直流电导和跳跃电导3个分量的叠加。温度主要影响弛豫分量和直流电导分量,且上述两个分量所对应的时间常量τ和直流电导率σdc随温度变化满足Arrhenius方程。

To quantitatively describe the variation of frequency domain spectroscopy（FDS） according to changes in temperature,moisture contents and aging states of oil-paper insulation,a modified Cole-Cole model was introduced to describe the characteristics of FDS.The parameters extracted from this model were proposed to be used as the characteristics of insulation performance of oil-paper.Methods of setting the initial value determination and an objective function for optimization were also proposed.Furthermore,FDS of oil-paper at various temperatures were measured by a three-electrode system,then the model parameters were extracted and analyzed.It is concluded that,in the range of 10-3～103 Hz,FDS of oil-paper insulation can be described by the modified Cole-Cole model with a single relaxation time constant.In the model,FDS is described as the cooperation of three individual components：relaxation,DC conductivity,and hopping conductivity.It is found that temperature plays a major role in affecting the components of relaxation and DC conductivity,of which the corresponding parameters（time constant（τ） and DC conductivity（σdc）） fit the Arrhenius equation.