Study of The Effect of Convective Heat Transfer on Cooling of Overhead Line Conductors Based on Wind Tunnel Experimental Results

Abstract: It is important to keep an overhead power line within rated operating conditions. Thus,an accurate prediction of the conductor's thermal and electrical behavior leads to an increasein reliability and eciency. Under DLR operation, the current rating is adjustedbased on ambient weather and solar conditions to allow for dynamic line loading. Therating adjustment takes into account the cooling mechanisms acting on the conductor. Inthis thesis, cooling by means of convective heat transfer is studied based on wind tunnelexperimental measurements of three dierent conductor samples. Convection contributesto most of the cooling; however, it is aected by wind speed and direction. Two angle ofattacks were studied (40 and 90), where perpendicular ow was found to result in bettercooling. The location of boundary layer separation highly aects the surface distribution ofcooling, which is non-uniform. Oblique wind ow results in reduction in overall cooling dueto earlier boundary layer separation. Finally, the surface average convective heat transfercoecient correlates non-linearly with the Reynolds number, where higher wind speeds andlarger conductor diameters can lead to signicant improvements in cooling while keepingrelatively low current densities. The existing standards of IEEE and CIGRE were found tooverestimate the eect of convective cooling for the specic experimental cases.