Thermal Assessment Method Optimization for Three-Core Cable Installation in Cable Trenches

With the continuous increase in urban power grid load, three-core cables are being increasingly used in urban distribution systems. The complex thermal environment and limited heat dissipation conditions in cable trenches directly affect the current-carrying capacity and operational safety of cables. Current thermal assessment methods for three-core cables installed in trenches often adopt simplified models that introduce certain errors, making it difficult to accurately reflect the actual thermal behavior during operation. The main objective of this study is to improve the accuracy of temperature assessment for three-core cables laid in cable trenches, thereby providing a more reliable basis for cable selection and operational management. By integrating theoretical modeling and field measurement verification, this study analyzes the applicability and limitations of the traditional IEC standard method and analytical models in the thermal evaluation of three-core cables. A three-dimensional heat conduction simulation model is subsequently developed, incorporating multiple coupled factors such as cable arrangement, trench dimensions, soil thermal resistance, and environmental ventilation conditions. The results show that the optimized thermal assessment model significantly reduces the prediction error of temperature rise compared to traditional methods, especially under high-load operation and multi-cable parallel installation scenarios, and can more accurately reflect the thermal distribution characteristics of the cables. The innovation of this paper lies in the validation of the model's engineering applicability through on-site measured data, providing decision-making support for cable installation design under different working conditions.