Research On Flashover Trip Probability Of Transmission Line And Clustered Faults Of Grid Under Sandstorm Circumstances

Sandstorm is one of the main meteorological disasters that lead to the tripping of overhead transmission lines and also the islanding of power system in Northwest China. With the increasing scale of power grid, damage risk of grid has increased remarkably during the occurrence of strong sandstorm and new method is needed to analyze mechanism of clustered faults of grid under sandstorm circumstances.In this paper, a deposition model of sand particle absorbed by electric insulator is proposed for calculation of equivalent salt deposit density(ESDD) and non-soluble deposit density(NSDD) on insulator surface based on meteorological data. The flashover trip probability model of transmission line is established based on insulator flashover calculation method by considering ESDD and NSDD of insulator surfaces for the region with high probability of sandstorm. The proposed model combines statistics research on insulator flashover and transmission line reliability theory to evaluate the trip probability of overhead transmission line flashover.Considering the occurrence of meteorological conditions with high air relative humidity such as fog and precipitation after sandstorm, the flashover trip probability model of transmission line is proposed in this paper to evaluate the impact of high air humidity on flashover trip of transmission lines. The proposed model combines statistics research on insulator flashover and research on influence of air humidity on leak current of insulator. Flashover trip probability of transmission line under meteorological conditions with high air relative humidity after sandstorm is calculated based on its series trait.Clustered fault under sandstorm is analyzed from the external meteorological perspective and internal grid operation perspective, in order to locate the faults set with high risk probability. In this paper, forewarning and risk assessment index system is built from the perspective of meteorological monitoring data of sandstorm, operation risk caused by clustered faults and topology changes of grid network. Through index, it is supposed to quantify the risk of influence of sandstorm on grid, locate the position of dynamic clustered faults set, narrow the scope of forewarning and analyze risk information of clustered faults and evaluate risk of clustered faults.