Analysis Of The Weather Conditions And Numerical Simulation For High-voltage Wire Icing Cases

By analyzing the data collected on the transmission lines of Central China power grid from 2009 to 2013 in Hubei Province,combining the MICAPS meterological data,atmospheric sounding and NCEP reanalysis data,the synoptic situation,duration and frequency of icing and the inversion layer during the wire icing are investigated.At last,using WRF model to simulate two precipitation icing.By analyzing the output data of WRF model,the equivalent icing thickness is estimated.The results show that the upper air circulation during icing process can be divided into three types:small groove development oriented type,transverse groove type and low trough eastward type.The occurrence frequency of each type is 43.8%,31.2%,25%.The characteristics of the weather conditions when wire icing occurs are:dew point temperature defici is small,larger relative humidity has advantageous to icing formation;3 hour allobar is mostly positive;when the velocity of north wind is less than 2.5m·s-1,it is prone to wire icing.The characteristic of the formation and dissipation time is:icing mainly occurs in the night,dissipation at noon.Respectively,wire icing mainly occurs in January,February,November and December and the average monthly icing hours in each month are 65h,42h,1 lh and 9h.The icing thickness and duration grow as the probability and strength of inversion increase.All icing process could be divided into two kinds:Precipitation Icing and Foggy Icing.A shear of wind direction from north to south could be found in the layer between 900 hPa and 700 hPa when Precipatation Icing occurs and a thick warm layer could be developed,which is favorable to the maintenance and development of the icing.The simulation results has the same varying trends with the observed temperature,wind speed and precipitation during icing.The simulated temperature profile,cloud water,rain and snow mass concentration can reflect the effect of atmospheric stratification and the microphysical field in the cloud on ice thickness preferably.It is found that the model captures the characteristic of "cold-warm-cold" atmospheric structure,and the simulated results of the inversion layer and the winter precipitation are consistent with the data of meteorological station.Using the output of WRF model and calculation model to calculate icing thickness,the error is small.It is indicated that the transmission line icing prediction system has a certain significance for wire icing disaster prevention.