The thermal inertia time constants and its influencing factors in the thermal dynamic process of overhead line and cable

Abstract

Due to the existence of thermal capacity, the conductor temperature of overhead line and cable changes later than current steps (thermal inertia), and the thermal dynamic process of the conductor contains the huge current-carrying potential. As an important symbol of thermal dynamic process, the thermal inertia time constant is of great significance to describe the characteristics of thermal dynamic process accurately. In this paper, the thermal inertia time constants of overhead line and cable and its influencing factors are studied based on the heat balance models, which can be solved by the fourth order Runge-Kutta method. Then the four factors including the current step, ambient temperature, wind speed and global radiation intensity are used to explore their influence on the thermal inertia time constant of overhead line, and the current step and soil temperature on cable. The numerical results show the effects of influencing factors on the thermal inertia time constant and provide a theoretical basis for a more detailed evaluation of the thermal dynamic process.