基于改进分数Poynting-Thomson模型的油纸绝缘受潮状态评估

Evaluation of Oil-paper Insulation Moisture State Based on Improved Fractional Poynting-Thomson Model

为实现对油纸绝缘设备受潮状态的量化评估,结合分数元的概念,建立了考虑直流电导率的改进分数Poynting-Thomson(P-T)模型。首先制备了5组不同水分质量分数的油纸绝缘样品,并测量了受潮样品的频域介电谱;然后采用改进分数P-T模型和改进Cole-Cole模型对介电谱进行拟合,分析了不同受潮样品与改进分数P-T模型参数的关系,并通过仿真研究了模型参数对频域介电谱的影响;最后结合实例验证了该评估方法的准确性。研究表明,改进分数P-T模型对不同受潮程度的油纸样品的频域介电谱拟合精度更优,且随着油纸样品水分质量分数的增大,模型参数εb、直流电导率不断增大,参数εa、弛豫时间常数逐渐减小;εa、εb、直流电导率与水分质量分数呈幂次关系,弛豫时间常数与水分质量分数具有线性关系,因此能够定量表征油纸绝缘设备的受潮状态。

In order to quantitatively evaluate the moisture state of oil-paper insulation equipment,an improved fractional Poynting-Thomson(P-T)model considering DC conductivity is established based on the concept of fractional element.Five groups of oil-paper insulation samples with different moisture content were prepared,and the frequency domain spectroscopy of the damped samples was measured.The improved fractional P-T model and the improved Cole-Cole model were used to fit the dielectric spectroscopy.The relationship between different damped samples and the parameters of the improved fractional P-T model was analyzed,and the influence of the model parameters on the frequency domain spectroscopy was studied by simulation.Finally,an example was given to verify the accuracy of the evaluation method.It is found that the improved fractional P-T model has better fitting accuracy for the frequency domain spectroscopy of oil-paper samples with different moisture degrees.With the increase of water content of oil-paper samples,the model parametersεb and DC conductivity increase,while the parametersεa and relaxation time constant decrease gradually.The model parametersεa,εb and DC conductivity have a power-law relationship with the water content,and the relaxation time constant has a linear relationship with the water content,so it can quantitatively characterize the moisture state of oil-paper insulation equipment.