Dispatching measures for improving the resilience of the Italian sub-transmission grid against ice and snow events

Global warming, also referred to as climate change, is the observed century-scale rise in the average temperature of the Earth and its related effects. Many scientific studies show that the climate system is warming. Considering the increase in extreme meteorological events related to this global warming, climate change is likely to make the national energy infrastructure increasingly vulnerable - especially in the absence of preventive actions. In recent years, the Italian transmission grid faced unusually severe weather events. Climate change is expected to worsen these extreme events such as snow blizzards and windstorms. This potentially increases the probability of damaging HV overhead lines and hindering the safety of the supply in the mountainous areas of the Alps and Apennines. In addition to the network infrastructure developments, Terna is improving operational procedures in order to manage extreme weather situations in real time. Real time control room operators can adopt preventative dispatching measures to increase the current on the critical lines and avoid the risk of ice sleeves (Joule effect). One of the possible preventive anti-icing measures is to create a reactive loop on the network. Where possible, the position of the on load tap changers of the autotransformers can be adjusted to create voltage differences and increase the reactive power flows on the critical lines. This article describes a real application of this approach in a portion of High Voltage network across the Apennines Mountains and Dolomites Alps.