Research On Risk Assessment Of Transmission System Under Ice Disaster

In recent years,overhead lines like UHV has been constructed at a large scale,so that icing disasters have occurred more and more frequently.Meanwhile,there are a few serious accidents such as disconnection and collapsed towel which poses a great threat to power grid's smooth operation.To reduce the impact of icing disaster on power grid,it is essential to take measures to assess transmission system's risk,which could set a early warning for probable disaster.The risk assessment of icing transmission system could be divided into three parts.The first part is to predict the ice thickness of transmission line at icing disaster.The second part is to analyze the relationship between icing level and line failure.The last part is to assess the risk of transmission system based on transmission line failure's data.The model of ice prediction which is based on fuzzy logic could avoid setting too many paraments in the traditional models.It merely need few meteorological factors to get accurate prediction and pass the verification of the measured data of some lines of Guizhou Power Grid.With the analysis of common accidents caused by ice disasters,the factors leading to line failures are attributed to three categories,icing overweight,line dancing,and insulators' ice flashover.So the relationship between three factors and lines is obtained respectively.Among them,the two factors,icing overweight and line dancing,use fuzzy theory to obtain the relationship between it and line failure.Compared with direct evaluation,the influence of various meteorological factors on line failure is more clear,which greatly simplifies the difficulty of model establishment.Taking the particularity of the ice disaster into consideration,the impact of ice disaster on the repair time of the line was discussed.In combination with the actual situation,the line is segmented,and finally the line failure model of multi-point outage is established.