Thermally limiting grid assets for temporary admissible transmission loading (TATL) in curative congestion management

This paper investigates thermally limiting grid assets for temporary admissible transmission loadings (TATL) under varying weather conditions. In a first step the thermal TATL is calculated through standards and accepted calculation rules for the relevant assets, overhead lines, cables, transformers and switchgears for standard dimensions and under worst-case weather conditions. The simulations calculate the thermal TATL for multiple preloads and one typical permissible load durations. First results show that under worst case weather conditions overhead lines and transformers are the limiting asset. Cables and switchgear show a thermal load capacity that is, by a factor of 2.8 to 5.7, significantly higher than that of overhead lines and transformers. Further results show, that with varying ambient temperatures and wind speeds overhead lines as well as transformers can become limiting in dependency of the type of overhead line.