Numerical analysis of thermo-electric field for AC XLPE cables with different service times in DC operation based on conduction current measurement

• Published in: IEEE transactions on dielectrics and electrical insulation Vol. 27; no. 3; pp. 900 - 908
• Main Authors: Yu, Jingzhe, Chen, Xiangrong, Meng, Fanbo, Paramane, Ashish, Hou, Shuai
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Aging; Alternating current; Cables; conductivity; Conductors; Current measurement; Electric cables; Electric fields; Electric potential; finite element methods; Fourier transforms; Numerical analysis; Power cable insulation; Power cables; Power distribution; Queuing theory; Service life; Space charge; Voltage; XLPE insulation
• ISSN: 1070-9878; 1558-4135
• DOI: 10.1109/TDEI.2019.008502

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.