Research on Temperature Sensing Method for Three-Core Cable Intermediate Joint Considering Three-Phase Load Imbalance

Temperature is a key factor affecting the insulation performance and operation safety of cable joints. Accurate acquisition of hot spot temperatures of cable joints is a difficult issue in cable operation and maintenance. Three-core cables may have unbalanced three-phase loads in actual operation. This paper takes a 10 kV three-core cable joint as the research object; based on the temperature field numerical simulation method, it analyzes the diffusion path of the main heat flow inside the joint and establishes an inversion model that fits the hot spot temperature of the joint through the surface temperature of the cable body. At the same time, considering the special situation of the unbalanced three-phase load of a three-core cable, the joint hot spot temperature inversion model of a three-core cable under an unbalanced three-phase load is further established. This paper further uses the cable joint multi-step unbalanced load temperature rise test to verify the accuracy of the cable joint hot spot temperature inversion model. The maximum error of the transient hot spot temperature inversion does not exceed 4.5 degrees C, and the steady-state error is within 3 degrees C. A higher inversion accuracy was achieved. The research results of this article can provide a reference for real-time monitoring of the hot spot temperature of cable joints.