Shan Bingliang, Du Chengqian, Cheng Junhua, Wang Wei, Li Chengrong
State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206, China.
Polymers (Basel). 2022 Dec 14;14(24):5478. doi: 10.3390/polym14245478.
Crosslinked polyethylene (XLPE) distribution cables are prone to segmented thermal aging after long-term operation owing to the large spatial spans and complex operating environments, and accurate residual life prediction of each aging cable segment could provide a theoretical basis and reference for performance monitoring, maintenance and the replacement of cables. Existing studies mainly focus on the residual life prediction methods for uniform aging cables, which are not suitable for segmented-aging cables. In this paper, a residual life prediction method for segmented-aging XLPE distribution cables based on the time-temperature superposition principle (TTSP) by non-destructive BIS measuring on site was proposed. Firstly, the applicability of the TTSP in the transformation of the changing process of elongation at break (EAB) of XLPE at different thermal aging temperatures was verified based on the Arrhenius equation. Secondly, to better simulate the thermal aging process under working conditions, XLPE cables were subjected to accelerated external stress aging at 140 °C for different aging times, and the corresponding changing process of EAB along with aging time was further measured. The relationship between the EAB of XLPE cables and aging time was well fitted by an equation, which could be used as a reference curve to predict the thermal aging trends and residual life of service-aged XLPE cables. After that, a calculation method for the transformation of the changing process of EAB of XLPE at different thermal aging temperatures was proposed, in which the corresponding multiplicative shift factor could be obtained based on the TTSP instead of the Arrhenius equation extrapolation. Moreover, the availability of the above calculation method was further proved by accelerated thermal aging experiments at 154 °C; the results show that the prediction error for the cable's EAB is no more than 3.15% and the prediction error for residual life is within 10% in this case. Finally, the realization of non-destructive residual life prediction combined with BIS measuring on site was explained briefly.
交联聚乙烯（XLPE）配电电缆由于空间跨度大、运行环境复杂，长期运行后易出现分段热老化现象，准确预测各老化电缆段的剩余寿命可为电缆性能监测、维护及更换提供理论依据和参考。现有研究主要集中在均匀老化电缆的剩余寿命预测方法上，不适用于分段老化电缆。本文提出了一种基于时间 - 温度叠加原理（TTSP），通过现场无损BIS测量对分段老化XLPE配电电缆进行剩余寿命预测的方法。首先，基于阿伦尼乌斯方程验证了TTSP在不同热老化温度下XLPE断裂伸长率（EAB）变化过程转换中的适用性。其次，为更好地模拟工作条件下的热老化过程，对XLPE电缆在140℃下进行不同老化时间的加速外应力老化，并进一步测量了相应的EAB随老化时间的变化过程。用一个方程很好地拟合了XLPE电缆EAB与老化时间的关系，该方程可作为参考曲线来预测服役XLPE电缆的热老化趋势和剩余寿命。之后，提出了一种不同热老化温度下XLPE的EAB变化过程转换的计算方法，其中基于TTSP而非阿伦尼乌斯方程外推可得到相应的乘法移位因子。此外，通过154℃的加速热老化实验进一步证明了上述计算方法的有效性；结果表明，在这种情况下，电缆EAB的预测误差不超过3.15%，剩余寿命的预测误差在10%以内。最后，简要说明了结合现场BIS测量实现无损剩余寿命预测的过程。
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