Radial Temperature Distribution of Aaac Overhead Line in Stationary and Transient Conditions

Commonly, dynamic line rating (DLR) calculates conductor temperature with a basic energy balance equation, which assumes homogeneous conductor temperature. With this 0D temperature assumption, however, there is a risk that inner layers of the conductor might exceed the limit temperature, if the rating current approaches its ampacity. Since conductor overheating should be avoided for operational safety, it is valuable to investigate radial temperature distributions of conductors. Throughout this study, therefore, homogeneous 1D conductor model with a radial temperature distribution is simulated in steady and transient states. For steady state simulations, radial temperature distributions under various ambient conditions are studied. Higher wind velocity, lower solar radiation, and lower ambient temperature make the temperature gradients more pronounced. Also, transient temperature distribution is modeled with a various stepwise current changes. When the core temperature reaches 80°C, momentous radial temperature distributions are analyzed. Compared to the steady state, transient phases show smaller temperature differences between core and surface. Both lower initial and higher final currents result in a flatter radial temperature distribution, whereas higher final currents cause faster transient heating. Compared to 0D calculations, the 1D model with a radial temperature distribution reduces the ampacity and prevents conductor core overheating.