Despite the good operating results of passive anti-icing devices installed by the Italian transmission system operator (TSO) on high-voltage overhead lines (OHLs), the increasing number and consequences of wet snow events have prompted consideration of other anti-icing measures. In particular, attention focuses on the thermal approach, which is intended to achieve – before, or in the early stage of wet snow events – the anti-icing current in OHL phase conductors where snow sleeve formation is foreseen. The authors carried out a specific anti-icing study with reference to a 132 kV critical path in an area of the Apennines, with simulation results illustrated in this study. Anti-icing measures investigated were (i) load shifting actions and (ii) insertion of shunt reactors used as ballast loads. The results show that shunt reactors are the most effective anti-icing measure. The main disadvantage of this innovative solution is the degradation of voltage regulation in the area. However, this downside can be limited by combining the insertion of reactors with control of autotransformers under load tap changers. Similar results are obtained from analyses of other critical areas. As a result of these findings, the Italian TSO is now undertaking the installation of the first ballast reactors.
