System for improving protective relay coordination with other protective elements in power system

摘要

The system first identifies the existence of a fault involving ground using the phase angle difference between negative sequence and zero sequence current on the power line. Phase angle differences within three specific ranges provide an indication of the presence of particular faults. Once a particular fault has been identified, such as a BC-to- ground fault, the fault condition is monitored to determine if the fault evolves, such as to a C-to-ground fault from the BC-to-ground fault. If an evolution is recognized, the protective relay is reset so as to coordinate its operation with downstream protective elements for the evolved fault.