The invention discloses a method and device for protecting a traction
feeder line of a single-phase power-frequency alternating-current electrified railway. The device comprises a protection function module, an auxiliary function module, a measuring and controlling module, a locking module and a communicating module; wherein the protection function module comprises a four-section distance protection unit, a current quick-breaking protection unit, a low-
voltage overcurrent protection unit, a high-resistance section I protection unit, a
voltage-loss protection unit and the like; in addition, the auxiliary function module comprises a broken-line alarm unit, a fault
ranging unit, a
harmonic analysis unit, a
load analysis unit, a self-checking unit, a fault recording unit and a GPS (
Global Position System) time
synchronizing unit; in addition, the measuring and controlling module comprises a remote metering unit, a remote signaling unit and a remote controlling unit; in addition, the locking module comprises an opening / closing locking unit and a locking reclosing unit; in addition, the communicating module comprises an RS485 interface, a selectable FDKBUS, an
optical fiber FDKBUS and an
Ethernet interface; in addition, a method for the four-section distance protection unit to recognize faults comprises the steps of: data preprocessing, network training and parameter generating, comprehensive judging and outputting.