Modeling ice-melting operation in conductors of a 6 kV DC overhead contact system

This study develops computational models and methods capable of accurately accounting for the single-phase time-varying traction load and the design features of current-carrying components during ice-melting operation in a 6 kV DC overhead contact system. The approach is based on a multiphase representation of powersystem elements using transmission-line and transformer models formulated in phase coordinates. The method was implemented in the industrial software Fazonord AC–DC. Simulation results showed that removal of glaze-ice and rime deposits from the contact suspension conductors is completed within 13–14 min, while melting on the contact wire proceeds approximately 1 min faster than on the messenger wire. Since the currents remain within permissible limits, the conductor temperature continues to increase following ice removal. Under these conditions, the allowable temperature of the contact wire (80°C) is reached after 21 min, whereas that of the messenger wire (100°C) is reached after 25 min. Therefore, the ice-melting process should be terminated once ice removal is completed, approximately 14 min after the start of operation. During the first 15 min of operation, the temperature of the hottest point in the step ‑ down transformers increases by 20–40°C, indicating elevated winding losses. Subsequently, the rate of temperature rise decreases, and the temperatures approach their maximum values. The study proposes a modeling approach that enables accurate determination of operating parameters in DC traction ‑ power systems during ice ‑ melting on 6 kV overhead contact conductors. The results can be used to simulate ice ‑ removal processes and determine the required melting time. They may also be applied to configuring relay ‑ protection devices for looped connection schemes between contact suspensions to the 6 kV terminals of traction substations.