Forecast-Based Line Rating Methods: Analysis of AAR and DTR Approaches

In recent years, environmental conditions have changed considerably due to the growing impact of climate change, which has caused a reduction in the average ampacity of power lines. At the same time, the push for decarbonization has led to increased utilization on existing overhead lines. The Italian Transmission System Operator has been investigating methodologies to increase the efficiency and transport capacity of the national electrical grid while minimizing the visual and environmental impact of infrastructure projects. To this end, in addition to designing and implementing projects with low visual and environmental impact, it is possible to identifying methods to make the best use of existing assets through minimal improvement or maintenance interventions. A widely adopted methodology in the international landscape is represented by Dynamic Thermal Rating (DTR) or Dynamic Line Rating (DLR) and Ambient Adjust Rating (AAR). The paper presents the methodological approaches of DTR models, comparing dayahead forecast to measured data, and AAR models, assessed over monthly or seasonal periods using historical forecasts, evaluating their forecast accuracy.