The Technology And Apply Of Single Phase Earth Fault Location That Applies To DA System

Distribution automation system can realize fast fault location and isolation, narrow thescope of failure outage, shorten failure outage time and improve power supply reliabilitywhen the fault happens. The single phase earth fault location is always a technical problembecause of the variable line structures, complex fault conditions, small fault currents, etc. Dueto the advantages of without additional equipments and small investment, the passive locationmethods using the fault information that produced by failure itself have become one of thedevelopment direction of distribution network fault location. And the similarity algorithmbased on transient currents does not apply in some special places. Current transformer polarityreverse connection which appears easily in the fields may also affect the effect of locationalgorithms based on current polarity. These factors greatly restrict the application of locationtechnology in distribution network automation system. Therefore, put forward a kind oflocation method which is suitable for distribution automation and has a high reliability byanalysis of single phase earth fault characteristics is an important way to enhance thereliability of power supply.As a result of disadvantages and demands above, this paper analysis the established theequivalent circuit model of single phase earth fault transient process, demonstrating that thetransient currents on two sides of the fault point have a low similarity which can be used tofault location. Puts forward a method by comparing transient and power frequency currentspolarities as the complement of similarity method by anglicizing the characteristic of transientand power frequency currents，making the location results more realizable. An ATP model isbeen established according by actual power distribution system to proof the method.Put forward the refit requirements for traditional distribution automation system making it has the function of fault location. Draw up the field testing program and accomplished thefield artificial grounding test. Verify the location method by anglicizing the field test and thesystem operational aspect.The location method comprehensive transient current similarity and the polaritycomparison between transient and power frequency currents putted forward by this paperwon’t be affected by Petersen coil and the polarity of current transformers has the advantagesof high reliability and wide adoption. The distribution automation system that has beenrefitted dose not has the dead zone of fault location and can achieve fault locating fast andreliably, which can support the automation of distribution system and the construction ofsmart distribution automation powerfully.