Pilot protection method and system for high-voltage direct-current line based on virtual grounding resistance

The invention relates to a high-voltage direct-current line pilot protection method and system based on a virtual grounding resistor, belongs to the technical field of relay protection, and solves the problems that an existing method is poor in transition resistance resistance and prone to maloperation when an external fault occurs. Comprising the following steps: acquiring conduction state information of a converter and characteristic parameters of a circuit on one side to which the converter belongs in a commutation period after the alternating-current and direct-current hybrid system breaks down; determining the characteristic frequency of the circuit according to the conduction state information and the characteristic parameters; determining virtual grounding resistance according to the characteristic frequency and the characteristic parameters; and determining a fault area according to the virtual grounding resistance. According to the technical scheme provided by the invention, the reliability and sensi