This paper presents an estimate for the influence of service time on the conduction current characteristics of a 10 kV AC XLPE. The experimental conduction current results show that the space charge accumulation threshold increases with service time. Fourier transform infrared (FT-IR) and differential scanning calorimetry (DSC) experiments show increased thermo-oxidative aging and reduced crystallinity as the service time increases. This results in deeper traps in the XLPE material which can be verified from isothermal surface potential decay experiments. Based on the experimental results, the numerical analysis of thermo-electric fields is carried out for 10 kV AC XLPE cables with different service times under bipolar DC operation mode. It shows that the DC power for 10 kV AC XLPE cable in bipolar DC operation is higher than the AC power, whereas the DC operating voltage and DC power increases with the service time. In order to ensure a safe and long service life of the cables in DC operation, a conductor temperature of 60 °C and DC operating voltage of 11 kV are recommended for 10 kV AC XLPE cables in bipolar DC operation.

中文翻译：

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基于传导电流测量的直流运行不同使用时间交流交联聚乙烯电缆热电场数值分析

本文对使用时间对 10 kV 交流交联聚乙烯的传导电流特性的影响进行了估计。实验导通电流结果表明空间电荷累积阈值随着使用时间的增加而增加。傅里叶变换红外 (FT-IR) 和差示扫描量热法 (DSC) 实验表明，随着使用时间的增加，热氧化老化增加，结晶度降低。这会在 XLPE 材料中产生更深的陷阱，这可以从等温表面电位衰减实验中得到证实。基于实验结果，对10 kV交流交联聚乙烯电缆在双极直流运行模式下不同使用时间的热电场进行了数值分析。结果表明，10 kV AC XLPE 电缆在双极直流操作中的直流功率高于交流功率，而直流工作电压和直流功率随着使用时间的增加而增加。为了确保电缆在直流操作中的安全和长使用寿命，建议双极直流操作中的 10 kV 交流 XLPE 电缆的导体温度为 60 °C，直流操作电压为 11 kV。