Comparative assessment of DLR performance for ACSR and HTLS conductors on a 400 kV transmission line under central European conditions

A steady-state dynamic line rating analysis was performed for a 400 kV overhead transmission line located in Slovakia, following the standardized methodology defined in CIGRE Technical Brochure 601. The investigated system corresponded to the V427 corridor originally equipped with aluminium conductor steel-reinforced 243-AL1/39-ST1A conductors. In the computational study, the conventional conductor was re- placed by high-temperature low-sag variants, specifically aluminium conductor composite core types, selected to preserve equivalent mechanical characteristics such as conductor diameter, mass per unit length, and ten- sile load, thereby minimizing structural interventions on the existing tower design. Meteorological data with a 15-minute temporal resolution, including ambient temperature, wind speed and direction, and global tilted ir- radiance, were obtained from the Open-Meteo application programming interface to ensure sufficient temporal granularity for the safe application of dynamic line rating. The thermal model incorporated Joule heating, solar heat gain, and convective and radiative cooling processes under steady-state conditions. The analysis compared annual ampacity profiles of both conductor types and quantified the potential benefits of dynamic line rating implementation relative to the conventional static line rating. The study provided a comprehensive technical ba- sis for evaluating the feasibility of adopting high-temperature low-sag conductors in combination with dynamic line rating as an effective and economically viable strategy for enhancing the transmission capacity of existing 400 kV corridors under realistic climatic conditions in the Slovak transmission system.