Investigation of the future Development of Icing Events in relation to Climate Change in the Alpine Region of Austria

At the main TSO of Austria over 5% of the total overhead line (OHL) grid is located in mountainous terrain, at elevations exceeding 1000 m above sea level. In Alpine regions, severe environmental conditions, especially icing combined with high wind speeds, pose a challenge to TSOs.

To ensure security of supply, the TSO expanded its ice monitoring system in 2021. Icing can affect security of supply by reducing internal clearances, causing flashovers when ice sleeves fall from a single phase. This detachment can cause the conductor to jump up and come too close to other phases. By causing damage to the towers structure, icing can result in the need for immediate shutoffs or repair work. In particular, uneven ice loads can damage the ground wire-peaks of towers, as these are most susceptible to icing. In some cases, a thin ice film combined with high wind speeds can lead to galloping, which places high stress on all components of an OHL.

To anticipate and understand icing events, the Austrian TSO monitors OHLs at twelve different monitoring sites.

In addition, the TSO has commissioned a study from the Austrian national service for geology, geophysics, climatology and meteorology on the development of icing in the coming decades, addressing the need for adaptation in an increasingly rapidly changing climate. Changes in the icing potential in Austria are derived for the near future (2021 to 2050) and the far future (2071-2100). Therefore, the icing model of the meteorological institute is used as methodical basis. The EURO-CORDEX dataset (0.11° grid – spatial resolution of approximately 12 km) is used as data basis. The TSO also provides information on icing damage to the OHL grid. For validation, we compared the icing model with data selected at several national weather stations during confirmed icing events in the past. In this study, we selected three different possible climate change pathways ranging from effective climate mitigation to a worst-case scenario.

On the basis of this study and the data collected at the monitoring sites in the Alpine region, the

TSO concludes that icing events in the Austrian Alps will increase, especially in the shoulder seasons. The paper will further discuss the results in terms of the expected quantity and load of icing events. These findings are crucial for the future planning of OHLs as well as for the planning of maintenance and monitoring measures. They can significantly improve the design and construction process for new OHLs. The results will not only contribute to improving the resilience of the power grid but will also be used to inform decisions regarding internal standards and external standardisation bodies.