On the Local Meteorological Causes of Severe Conductor Icing by Using Numerical Computation Models and In-situ Observations

Based on the icing thickness and the monitored temperature and humidity data of UHV transmission lines, this paper employs the Makkonen icing model to study the impact of ambient temperature, wind speed and liquid water content on the collision rate and freezing rate during the conductor icing process, combining with the monitoring data of UHV transmission lines in central Guizhou Province on January 23–29, 2018. The icing sensitivities of ambient temperature, wind speed and liquid water content are explored under the four types of terrain including leeward slope, mountain top, tuyere and mountain foot. Results show: 1) When the ambient temperature is lower than 10°C, the icing growth rate is close to 0. The icing growth rate first increased rapidly with the increase of ambient temperature and then increased slowly and steadily. At the same temperature, the smaller the diameter of the super-cooled water droplet, the stronger the icing growth rate. 2) The icing growth rate increases steadily with the increase of wind speed. Under the same wind speed, the smaller the diameter of the super-cooled water droplet, the weaker the ice growth rate. 3) In the ambient temperature sensitivity, the sensitivity at the foot of the mountain and the leeward slope is the highest, while the lowest at the mountain top. In the wind speed sensitivity, the sensitivity at the leeward slope is the highest, while at the lowest at the mountain top. In the sensitivity of liquid water content, the sensitivities of the four types of terrains exhibit marginal difference, and the sensitivity coefficients are about 1. Our present work refines the terrain coefficients based on four types of terrain structures, so the correlation coefficient between the simulation results and the monitoring data is maintained at 0.746, and the root mean square error is reduced from 4.27 mm to 3.5 mm.