Temperature control of aerial current-carrying conductors by insulation surface temperature

This study aims to develop and carry out numerical analysis of a methodology for determining the temperature of conductors of insulated wires, which implies measuring electric current and insulation surface temperature as well as using Smart Grid technology. We used a mathematical model of thermal conditions for conductors in the form of an algebraic fourth-degree equation and the Ferrari method to solve this equation. Simulation of temperature fields providing comparison results was carried out using the finite element method in the COMSOL Multiphysics. The temperature of conductors was measured taking into account measurement errors and using the least squares method together with the golden-section search. The finite element method made it possible to study temperature distribution in the section of SIP-3 shielded wire as well as in its insulation surface. The dependencies of changes in the maximum and minimal temperatures of the wire insulation surface were obtained as a result of simulation; these dependencies were influenced by wind speed changes at the maximum permissible temperature of conductors. The difference between the maximum and minimum surface temperatures was shown to reach approximately 25°C at wind speeds of 3–4 m/s. Our study resulted in function, the minimization of which makes it possible to find the temperature of current-carrying conductors of shielded wires by values of the insulation surface temperature. Comparative analysis of the developed method for determining the temperature of conductors and the finite element method provided the calculation error of 0.44°C given accurate settings of electric current value. The study results substantiate the need to take into account the nonuniformity in temperature distribution on the insulation surface of shielded conductors when monitoring power lines. The developed methodology for calculating the temperature of conductors by measurement data provides high accuracy at almost any nonuniformity in the surface temperature provided that the current measurement error equals 5% or less.