接地电流谐波多维特征评估XLPE电缆热老化

Multidimensional Characteristic Analysis of Grounding Current Harmonics for Thermal Aging Evaluation of XLPE Power Cable

热老化是影响电缆绝缘寿命的主要因素之一,本文通过研究热老化交联聚乙烯电缆的接地电流谐波特征来评估电缆热老化状态。在实验室条件下以实际运行电缆为试样开展加速热老化实验,测试分析不同老化程度下电缆接地电流的变化规律,采用改进变分模态分解法提取接地电流中的敏感谐波,并建立接地电流谐波时域、频域、相对能量和样本熵等多维特征参数与电缆热老化程度的关联关系。研究发现,热老化使谐波的相对能量增大的同时,也增加了谐波序列的无序度。

Thermal aging is one of the main factors affecting the service life of cable insulation.In this paper,the har-monic characteristics of XLPE power cable grounding current are investigated to evaluate the thermal aging state of ca-bles.First,an accelerated thermal aging experiment with an actually operating power cable as a sample was carried out under the laboratory conditions.Second,the variation rules for the grounding current of cables at different aging degrees were tested and analyzed.Third,the improved variational mode decomposition algorithm was used to extract sensitive harmonics from the grounding current,and the correlations between the multi-dimensional harmonic characteristic pa-rameters of grounding current(e.g.,time-domain parameters,frequency-domain parameters,relative energy and sam-ple entropy)and the thermal aging degree of cables were established.It is found that thermal aging boosts the relative energy of harmonics while increasing the disorder of the harmonic sequence.