Impacts of soil-frost on wind-related energy grid disturbances

A large share of the disruptions in electricity distribution in Finland is caused by wind and windstorms. Snow loads on trees are another or complementary cause for such disruptions. The disruption proneness of power supply to strong winds in Finland, and in similar densely forested countries, seems to reduce in the presence of soil frost.

In a still ongoing study, NordicLink, funded by Nordforsk, we combined the power distribution disruption data (2015-2023, by event) with weather and soil temperature information and estimated the impact of wind and soil frost on disruption occurrence probability. The objective of our work was to find a relation between wind gust speed and the number of power supply interruptions and to determine the effect of soil frost on wind-related faults in the electricity distribution system in Eastern Finland. 

The results indicate that when soil frost is present, trees are less likely to fall onto power lines during high-wind events, reducing the risk of power outages. The frozen soil provides additional support to the trees, making them less likely to uproot under the force of the wind. As expected, we found a positive correlation between the number of power outages and wind speed and a negative correlation between soil frost and wind-related power outages.

The warmer climate will most likely decrease the soil frost, and thus increase the possibility of wind-related power outages in Finland or similar high-latitude countries. However, further research is needed to fully understand the complex relationship between soil frost, wind events, and power outages, and to identify the most effective strategies for mitigating the risk of such outages in the future.