The effect of day-ahead weather forecast uncertainty on power lines’ sag in DLR models

In the last decade, dynamic line rating (DLR) as a novel and cost-effective transfer capacity calculation method has been getting into the scope of transmission system operators (TSOs). By applying DLR method, it is possible to increase the ampacity of the overhead lines (OHLs) averagely in 95% of the time based on the monitoring of the actual weather conditions in the vicinity of the conductors. On the other hand, one important pillar during the application of this method - from the aspect of the TSOs - is the day-ahead transfer capacity prediction for the determination of generation schedules, which requires accurate weather forecast. By using accurate weather parameters as an input of DLR models, there is no sag violation at the maximum allowable conductor temperature. Otherwise, getting precise weather forecast is almost impossible; this affects the sag and, in this way, the whole DLR method. The aim of this article is to present how sag and clearance of the OHL spans change due to weather forecast uncertainties. For the simulations, field data from an OHL equipped with line monitoring sensors and weather stations are applied. Sag-clearance monitoring is also an important aspect in case of DLR applications regarding to the electric and magnetic field strength and distribution. Because of the potential threat for general public and occupational personnel, monitoring of sag increment might be an important aspect in the state of the art DLR related researches.