Spatial and Temporal Distribution Characteristics， Numerical Simulation and Weather Science Causes of a Large Scale Icing Process on UHV Transmission Lines in Yunnan-Guizhou Plateau

Abstract

Utilizing the ice thickness data， temperature data， relative humidity data， meteorological reanalysis data and topographic elevation data obtained from the icing monitoring system of ultra-high-voltage transmission lines in China Southern Power Grid， combined with the numerical model of icing， this paper analyze the spatial and temporal distribution characteristics of a large-scale sustained icing on transmission lines in the Yunnan-Guizhou Plateau during January 24 -28， 2018.In addition， the cause of the weather is analyzed.Results show that： （1） Transmission lines in central part of Guizhou Province are the first to monitor the ice-covered， with an overall ice-covered duration length of 60 to 120 hours， and ninety percent of transmission lines have an ice-covered thickness larger than 15 millimeters， with a maximum can reach 50.74 millimeters.Transmission lines in Yunnan Province and northeastern Guangxi Province have an ice-covered duration length of 0 to 10 hours and 40 to 80 hours， respectively， with a maximum ice-covered thickness no more than 25.22 millimeters.（2） The correlation coefficient between the model simulation results and the monitoring data is above 0.9， passing the significance test with ninety-five percent confidence level （when the P value is equal to 0.049）.However， complex terrain has a significant impact on the simulation icing on transmission lines.Best simulation of transmission line ice cover for altitudes of 920 -1060 m， slopes of 7.73°~20.3°， northwest pass and northeast pass.The liquid water content of transmission lines with elevations below 920 m or slopes greater than 20.3° is overestimated.Underestimated wind speeds on transmission lines in southwest and southeast pass.The simulation results for the above two terrain backgrounds are not good.（3） The "high north and low south" potential height field and the "two troughs and one ridge" stable circulation situation in Eurasia will continuous steadily transport the cold air gathered in the East Siberian region to the south of China.In addition， the active southern branch trough and the existence of low-level southwest rapids （wind speed larger than twenty meters per second） make the abundant water vapor in the South China Sea & the Bay of Bengal continuously transported northward， providing stable water vapor conditions for this widespread ice cover event.

Keywords

• icing simulation
• temporal and spatial characteristics
• micro-topography
• micro-meteorology