Modelling of convective cooling on conductor thermal rating methods

摘要

Thermal rating of overhead line (OHL) conductors is mainly calculated according to standard methods of IEEE, CIGRE, and IEC which based on the heat exchange mechanisms of the conductor and surrounding. Different convective cooling models are implemented by the standards thus significant discrepancy is recorded during low wind conditions. COMSOL is used to investigate the impact of the more accurate mixed convective cooling model on OHL conductors so as to investigate the appropriateness of standard methods. At less than 0.2 m/s, conservatism is obtained through the IEC model while the IEEE and CIGRE models are not entirely appropriate. The IEEE and CIGRE models violate the designed 70° and 180° Drake conductor by 4.35° and 20.9° respectively. These temperature violations which are also the ageing risks contribute to 28.74 mm and 6.19 mm incremental in sag for 300 meters Aluminum-Alloy Conductor (AAAC) and Aluminum Conductor Composite Reinforced (ACCR) conductors respectively.