Thermal Analysis of HMCPL Shielding System for High Voltage Power Lines in Confined Environments

This article presents a comprehensive thermal analysis of the high magnetic coupling passive loops (HMCPL) shielding system applied to high-voltage (HV) power lines installed in confined underground environments. The study evaluates the thermal behavior of single and double three-phase HV cable configurations, with and without HMCPL shielding, under both nominal (up to 1300 A per phase) and transient overload conditions (up to 2200 A per phase for 2 h). An experimentally validated 3-D thermal model developed in COMSOL Multiphysics is proposed and benchmarked against laboratory measurements on a 1600 mm² HV cable in a scaled tunnel, showing a maximum deviation below 1.5 ^∘ C on both conductor and sheath temperatures. The results indicate that the HMCPL system increases conductor temperature by about 13–15 ^∘ C at rated load (e.g., from approximately 69 ^∘ C to 83 ^∘ C in the joint chamber double three-phase circuit configuration) but that the maximum temperatures remain within the limits prescribed by IEC 60287 and manufacturer specifications (90 ^∘ C in steady state and 100 ^∘ C under short-term overload). The main novelties of this work are: 1) the development and experimental validation of a thermal model explicitly tailored to HMCPL-shielded HV cables in confined chambers, 2) the assessment of both single and double three-phase circuit cable layouts including worst-case overload scenarios, and 3) the demonstration that effective magnetic field mitigation via HMCPL can be achieved without compromising thermal compliance and long-term reliability of HV underground installations.