Study on Length Variation of Transmission Line under Different Operating Conditions

Abstract

The mechanical calculation model of ice thickness is used to calculate the equivalent ice thickness coating on transmission line, in which the length of the conductor is one of the important basic parameters. The conductor is faced with various complicated working conditions in nature, and the temperature or the load variation will change the length of the line. It is of great significance to study the length variation of the transmission line for establishing the mechanical calculation model of ice thickness. In this paper, three Aluminium-alloy Conductor Steel-reinforced applying in 110kV - 500kV transmission line are selected to study their length variations under four different conditions, such as large temperature difference, heavy ice, high wind, heavy ice and high wind combined condition. The calculation results show that the length variation caused by the large temperature difference and the ordinary wind (<10m/s) can be neglected. There is little effect on line length with slight ice (<10 mm), but its effect is significantly enhanced with increasing ice coating. Meanwhile, the ice increases the wind receiving area of the conductor, so that the influence of the wind load increases. In the calculation model of ice thickness, the influence of heavy ice and high wind on the length variation should be fully considered to make calculation result of equivalent ice thickness more accurate.