Thermal Aging State Evaluation Method for Submarine Cable Insulation Based on High-Voltage Frequency Domain Dielectric Characteristic Quantity

The cross-linked polyethylene (XLPE) is widely used in the insulation of the seam cable because it has good electrical performance, mechanical performance and heat resistance, and it is the basis for ensuring the insulation and safeness of the waters. However, during operation, high voltage 500 kV submarine cable is susceptible to complex thermal, electrical, mechanical and environmental stresses, resulting in an intrinsic aging process with time-varying characteristics of the cable insulation medium. Therefore, it is of great significance to carry out the analysis of the deterioration characteristics of insulation medium and the non-destructive state evaluation method of high voltage 500 kV submarine cable for the operation and maintenance of submarine cable. In this paper, the high-voltage frequency domain dielectric response test of XLPE submarine cable under different test voltage and different test temperature conditions is carried out, and the results show that the dielectric loss factor of the tested submarine cable gradually increases with the increase of test voltage and test temperature in the frequency range of 10−3–10−1 Hz. The correlation between the relative loss λ and the elongation at break retention rate K at different test temperatures is established, and a method for evaluating the insulation aging state of XLPE submarine cable is proposed to realize the effective evaluation of the insulation aging state of submarine cable.