Intelligent accurate line selection device and method for single-phase earth fault of power grid

The invention relates to an intelligent accurate line selection device and method for a single-phase earth fault of a power grid. The device comprises a line selection controller and a selection-assisting current increment device, the line selection controller is used for collecting the zero-sequence current of the power grid after the power grid has a single-phase earth fault, and obtaining the initial zero-sequence current value of each phase of the power grid. The line selection controller is also used for controlling the selection-assisting current increment device after obtaining the initial zero-sequence current value; the selection-aided current increment device is used for injecting selection-aided increment current into the power grid with the single-phase earth fault; after the selection assisting increment current is injected into the power grid with the single-phase earth fault, the zero-sequence current of each phase of the power grid with the single-phase earth fault is collected, and a group se