Abstract
Icing can adversely influence electric power system security. Two main issues are caused by icing: the overload of transmission lines, and the reduction in the insulation ability of the insulators. Most previous research has focused on the flashover characteristics of ice-covered insulators, but research on the icing process of the insulator is seriously lacking. Considering the effect of icing shape, the outer airflow field of an insulator was calculated and the local collision efficiencies of water droplets (β1) were investigated according to the Lagrange algorithm. The simulation showed that the values of β1 on the insulator edge and rod are much higher than on the insulator surface, and both were significantly influenced by the wind speed and median volume diameter (MVD) of the water droplets. Based on thermal balance equations, a dynamic dry-growth icing model was established. Using the natural icing conditions of Xuefeng Mountain (China) as an example, validation experiments were conducted on a composite insulator and the climate parameters measured by multi-cylinders were used to model the icing shape and mass. The results indicate that high wind speed and low temperature increase icing rate; the icing was mainly concentrated on the windward side and the greatest horizontal thickness was generally on the insulator edge. The dry-growth model had an average error lower than 25% for icing thickness and an average error lower than 20% for icing mass, which were affected by icing roughness.
Highlights
Icing is a normal phenomenon in cold regions, posing a serious problem for electrical systems.Two main issues are caused by icing: the overload of transmission lines, and the reduction in the insulation property of insulators [1,2,3,4]
Makkonen [8] proposed that the growth rate of ice on transmission lines is related to environmental parameters including temperature, wind speed, liquid water content of air, and median volume diameter (MVD) of the water droplet distribution
Of changeless wind direction during the test, the dry-growth icing had typical regional characteristics, changeless wind wind direction direction during during the the test, test, the the dry-growth dry-growth icing icing had had typical typical regional regional characteristics, characteristics, changeless with the icing mainly concentrated on the windward surface of insulator
Summary
Icing is a normal phenomenon in cold regions, posing a serious problem for electrical systems. Based on heat balance equations, Maeno and Makkonen [5] studied the process of wet-growth icing, and the results showed that the growth rate of an icicle increased with decreasing temperature and increasing wind speed. Considering the movement of supercooled water droplets in the air, Makkonen [8] proposed an ice growth model according to collision efficiency, sticking efficiency, and accretion efficiency on transmission lines. Makkonen [8] proposed that the growth rate of ice on transmission lines is related to environmental parameters including temperature, wind speed, liquid water content of air, and median volume diameter (MVD) of the water droplet distribution. The introduced model [9] did not consider the effects caused by changing airflow fields and could not accurately obtain the collision efficiency of a changing icing shape. The related insulator icing experiments were performed at the Xuefeng Mountain Natural Pollution and Icing Observation Station, located in Hunan Province, China, at an altitude of 1400 m [12]
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