Summary and Adaptability Analysis of Implementation Schemes about Single-Phase-to-Ground Fault Diagnosis in Distribution System

Single-phase-to-ground(SPG) fault accounts for about 80% of faults in distribution system, which will easily cause system overvoltage and multi-point-grounded short-circuit fault. As a result, fault location should be accurately and quickly determined after SPG fault occurs. Due to different neutral-point grounding modes in distribution system, the fault characteristics are various when SPG fault occurs. Therefore, the fault detection methods are different under different neutral-point grounding modes of the system, and the acquired data and configured equipment may also be different. According to the types of monitoring devices applied, SPG fault diagnosis solutions could be divided into three categories: fault-indicator scheme, intelligent-monitoring-terminal scheme and boundary-switch scheme. According to diagnosis principle, the solutions are further subdivided into transient-recording method, directional-adaptive method, signal-injection method, multilevel-directional protection method, phase-asymmetry detection method and so on. This paper firstly summarizes the existing implementation schemes for SPG fault diagnosis including the principle and implementation method. Secondly, adaptability comparison is done among different schemes, and suitable SPG fault handling schemes for different neutral-point grounding systems are put forward. Finally, the development direction of SPG fault handling technologies in the future is prospected, which will effectively promote the level of safe and reliable operation in distribution system.