A shift from conventional round wire overhead lines (OHLs), e.g. the aluminum conductor, steel-reinforced (ACSR) to compacted types such as the all-aluminum-alloy conductor (AAAC) is seen taking place, where the AAAC type has a smooth surface as a result of outer trapezoidal strands.
In windy situations the difference in convective cooling as a function of the outer strand types is not well described, however, it is known that the roughness of the surface increases the convective cooling at high wind speeds. The roughness of the surface is taken into account in CIGRÉ models, but is based on simplified calculation coefficients.
A more detailed calculation method is thus desired, and could be in the form of FEM modeling (e.g. in COMSOL Multiphysics), which must include a detailed representation of the convective air flow on a accurate conductor model in wind situations, taking into consideration the transition between laminar and turbulent air flow etc.
Models of both rough and smooth surface type conductors should be set up, and the results compared with the intention of indicating the true difference in cooling capabilities between these two types of overhead conductors.