Modelling precipitation cooling of overhead conductors

This paper presents a precipitation-based conductor cooling model for use in power line ampacity rating applications and line temperature calculations. It is aimed at better modelling of a conductor’s temperature by incorporating the line cooling caused by precipitation falling onto power lines. The expanded thermal model quantifies the additional gain of current-carrying capacity for power transmission networks incorporating advanced Dynamic Thermal Circuit Rating systems.The precipitation cooling model is verified against observations made by a power transmission utility using a commercial line current and temperature sensor clamped onto an actual power transmission line. The accuracy of the precipitation model is assessed both quantitatively using standard error measures, and qualitatively in terms of fit of the model to real world data. The precipitation-based cooling extension shows a significant improvement over IEEE Std. 738-2006 in the modelled accuracy of the conductor temperature. It suggests a substantial increase in available ampacity during periods of precipitation.

► The IEEE Std. 738-2006 is used by power utilities to determine line ampacity.
► We developed its extension to include line cooling caused by falling precipitation.
► The extended model was verified against sensor records from an industry partner.
► The new model achieved high accuracy of the modelled conductor temperature.
► If used for dynamic thermal rating, the model can increase realized line capacity.