A protection scheme for phase-to-phase faults based on spectrum characteristic of fault-generated high-frequency transient signals

When a fault occurs on a transmission line, fault-generated high-frequency signals contains a lot of information about fault. This paper proposes a protection scheme for phase-to-phase fault in transmission line based on spectrum characteristic of fault-generated high-frequency signals. The difference of fundamental natural frequencies in both ends of transmission line is used to determine whether a fault is internal or external. The scheme can reduce trip time if the fault is an internal fault and does not misoperate if the fault is external. It also can identify chose-up faults. The scheme performance was proven using Power System Computer Aided Design (PSCAD) in 500-kV power system considering critical fault cases.