Thermal Modeling of Distribution Lines for Power Systems Studies

Abstract

Distribution lines are the main arteries of electric power systems. Distribution lines are the most vital component of a power system because these lines are needed to transport energy from one place to another. As important as distribution lines are to a system, temperature variations are rarely considered for system analyses. This leads to a lack of fidelity in many studies. Traditionally, computational power limited the number of modeling considerations incorporated into a systems study. In today's era, computers are becoming more powerful and, thus, much faster. Due to the change in computational power, more variables, such as the effects of temperature on a system, can be studied. The goal of this study is to show how much of an impact conductor temperature has on a small system, which can then be scaled for larger systems. The distribution lines in the IEEE 13 Node Test Feeder were used for the study. In the standard mathematical model, all the distribution lines use a common 50°C operating temperature as an input. Instead of using this value, a finite element analysis (FEA) simulation was created of each of the eight overhead distribution lines and two underground distribution lines. These models use loading current, ambient temperature, and thermal boundaries as their inputs to calculate a more accurate resistance. These new values are then used to derive updated impedance matrices for each line to be used to simulate the power flow with accurate temperature-based values. A comparison is performed using distribution analysis software between the original and newly derived results. In addition to ambient temperature, edge cases are evaluated, such as significant convection-cooling due to wind or radiation heat due to direct sunlight.