The power-frequency component is no longer suitable for faulty feeder identification in a resonant grounded system. Influenced by the incorrect polarity connection of voltage transformer and current transformer

faulty feeder is apt to result using feeder identification based on transient current polarity or transient reactive power direction comparison. The distribution differences between transient and power-frequency current as well as transient and power-frequency reactive power for single-phase earth fault in the compensated system are analyzed

based on which

two faulty feeder identification methods based on combined transient and power frequency components are proposed. A faulty feeder is one with a polarity different from that of both the transient zero sequence current and power frequency zero sequence current of healthful feeders

or

a feeder is identified as a faulty one if its transient reactive power and power-frequency reactive power have different directions. The proposed methods have fairly good faulty feeder identification reliability for their ability of avoiding incorrect polarity connection of voltage transformer and current transformer. The feasibility of the new methods is verified by both digital simulation and field test data.