A Burial Depth Detection Method for Three-Core 220 kV Submarine Cables Based on the Optical Fiber Monitoring Temperature

Abstract

Submarine cables are vital to the safe and reliable operation of power systems. However, due to the geological structure and the operating environment of the seabed, submarine cables are often exposed. There is no simple and effective method to calculate the burial depth (BD). To solve the above problems, we propose a method to calculate the BD based on optical fiber monitoring temperature. At first, a finite element simulation model of 220 kV three-core fiber optic composite submarine cable is established, and the temperature of the submarine cable’s outer sheath is obtained by optical fiber monitoring temperature. The thermal resistance of the submarine soil is calculated from the outer sheath temperature, seabed surface temperature and loss. Another representation of seabed soil thermal resistance is obtained according to the standard IEC-60287, and the equation is established to solve the burial depth. We find that, when the actual burial depth is 0.3 m, the maximum absolute error of burial depth calculation is only 13.6 cm. This method is accurate when the actual burial depth is shallow. The method can obtain the real-time burial depth of submarine cable directly from the optical fiber monitoring temperature, which has the advantages of being simple and feasible as well as important research and application value.