Hotspot Temperature Inversion of 110 kV Single-Core Cable Joint Based on Function Fitting

Abstract

Cable joint temperature is a key factor affecting its insulation performance and service life. To avoid direct measurement which may damage the cable joint structure, this paper adopts the method of inverting the joint hotspot temperature by surface temperature, where a fitting function and a thermal circuit are established to complete the inversion. Firstly, a transient simulation is used to obtain simulation temperature data samples of cable joint and body, not only as a comparison for inversion results, but also for constructing an inversion function connect the two variables by function fitting method. Then, a transient thermal circuit model recommended by IEC60853 is established at the cable body to calculate real-time cable body core temperature from the surface temperature. Finally, substituting the real-time cable body core temperature into the fitting function to obtain the joint hotspot temperature as inversion results. For error analysis, we compare the simulation results with the inversion, and the influence of heat dissipation changes on the inversion accuracy is studied. The research results indicate that the maximum error is controlled within 7 ℃ under relatively unfavorable conditions, which can meet the engineering needs.