Detection Method for Equivalent Ice Thickness of 500-kV Overhead Lines Based on Axial Tension Measurement and Its Application

Abstract

Overhead line icing may threaten the operational stability of power grid. In this paper, a detection method for equivalent ice thickness of 500 kV overhead lines based on axial tension measurement was proposed. Firstly, according to the tension of insulator string when the transmission lines are not covered with ice, the horizontal distance from the lowest point of the transmission line to the tower on the side where the tension sensor is installed is calculated. Secondly, the state equation of the transmission line in the whole tension section is established. Then, the state equation is solved by iterative method. The initial ice thickness is taken as 0 mm. The ice thickness when the iteration value of tension <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> is equal to the measured value of tension <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F</i> is taken as the equivalent ice thickness of transmission lines. The actual cases of single span transmission line and multi-span transmission line were used for verification and application effect analysis of the proposed method. The results show that the detected results of this method were consistent with the artificial ice observation values of typical 500 kV single span and multi-span transmission line cases. The accuracy of the proposed method can be further verified through finite element simulation analysis. The variation trends of the detected ice thickness is consistent with the icing conditions created by the meteorological factors during the same period, and can be verified by the icing photos captured on site.