Analysis of discharge defect in buffer layer for highvoltage cable and rejuvenation method

The breakdown accident for the cable line caused by the defect of the buffer layer poses a challenge to the maintenance and operation of the cable. The long-term operation of cable will cause the changes in physical properties of the buffer layer and affect the stable operation of the cable. Therefore, this paper establishes an distributed electric network model for analyzing the discharge defect of buffer layer under different states. The calculation methods of each component in the model are proposed. The axial distribution of potential between the corrugated aluminum sheathing and the buffer layer under different contact conditions was analysed. The results show that the continuous development of the corrosion product in the axial direction will increase the voltage between the corrugated aluminum sheathing and the buffer layer. The discharge risk can be effectively reduced by injecting rejuvenation fluid between the metal sheath and the buffer layer. The effectiveness of the rejuvenation method can be quantified by using the distributed electric network model.