基于修正分数Poynting-Thomson模型的高压XLPE海缆绝缘评估

Evaluation of high-voltage XLPE submarine cable insulation based on modified fractional Poynting-Thomson model

为利用频域介电谱准确评估高压交联聚乙烯(XLPE)海缆的绝缘状态,建立考虑直流电导率的修正分数Poynting-Thomson模型(分数P-T模型)以解析高压XLPE海缆的介电特性。首先,通过加速老化试验制备不同老化程度的高压XLPE海缆试样,并测得各组老化试样的力学、理化和介电数据。然后,应用修正分数P-T模型对实测介电曲线进行拟合,对比修正前后分数P-T模型表征实测介电曲线的效果。最后,通过仿真探究模型参数对介电曲线的影响规律,构建模型参数与绝缘程度之间的联系,将提出的老化特征参数与断裂伸长率(EAB)进行量化研究。研究结果表明,修正分数P-T模型能够准确拟合出不同老化程度高压XLPE海缆试样的介电曲线,提出的老化特征参数α、ε_(a)、ε_(b)和σ_(dc)可实现对高压XLPE海缆绝缘状态的量化评估。

To accurately assess the insulation status of high-voltage cross-linked polyethylene(XLPE)submarine cables using the frequency domain dielectric spectroscopy,a modified fractional Poynting-Thomson model(fractional P-T model)was established considering direct current conductivity to analyze the dielectric properties of high-voltage XLPE submarine cables.Firstly,high-voltage XLPE submarine cable samples of different aging degrees were prepared through accelerated aging tests,and the mechanical,physicochemical,and dielectric data of each group of aged samples were measured.Subsequently,the modified fractional P-T model was applied to fit the measured dielectric curves,comparing effectiveness of the fractional P-T model before and after modification in characterizing the measured dielectric curves.Finally,through simulation,the influence of model parameters on the dielectric curves was ex-plored,relationship was established between model parameters and insulation levels,and a quantitative study was conducted of the proposed aging characteristic parameters with the elongation at break(EAB).The research results indicate that the modified fractional P-T model can accurately fit the dielectric curves of high-voltage XLPE submarine cable samples with different degrees of aging,and the proposed aging characteristic parametersα,ε_(a),ε_(b),andσ_(dc) can realize the quantitative assessment of the insulation sta-tus of high-voltage XLPE submarine cables.