Test And Verification Of Single Phase Earth Fault Location Technology Based On DA System

Distribution automation(DA)system can quickly locate and isolate faults after the failure of the distribution network,so that it can narrow the scope of failure outage,shorten failure outage time and improve power supply reliability.The single phase earth fault location is always a technical problem because of the variable line structures,complex fault conditions,small fault currents,etc.There are some problems on positioning signal and applicability of traditional single phase earth fault location methods.As a development direction,fault location method based on transient signals' application in the field is not clear,it is necessary to test its performance or positioning accuracy and validation,which concerns whether it can be used widely in the field or not.This paper analyzed the fault characteristics of monitoring branch line system,improved the locating criterion of the transient current waveform comparison locating method and verified it through the simulation software.Through the static model test,data analysis and field test,set different parameters,different fault locations,different types of faults,to verify the location method based on transient current waveform comparison.Analyzed the problem of the inconsistent waveforms send by different devices.Aiming at the problem of device active,the paper put forward an active method that use the transient current mutation.This paper proved the accuracy of single phase earth fault location technology based on transient current waveform comparison working performance and accuracy in not monitoring branch line system(overhead line)and monitoring branch line system(cable line)through software simulation,the static model test,field data analysis and field test,which possess superior reliability,concluded that the cause of the error locations are caused by terminal active in advance or delay,not by location algorithm.Put forward a kind of device active method based on transient current mutation,which start device when two sampling points' amplitude in three consecutive sampling point are greater than threshold value.Preliminary determination report that the inconsistent waveforms send by different devices is caused by CT saturation.By the work of this paper,verified the applicability of fault location method based on the transient current waveform comparison in the field,found and solved some problems existing in the field,which laid a foundation for its application in large-scale,promoted development of DA system in aspect of single phase earth fault location.