Method and system for a pilot directional protection of LCC-HVDC lines based on virtual grounding resistance

A method for a pilot directional protection of LCC-HVDC lines based on virtual grounding resistance, comprising:

• Obtaining a conduction state information of a converter and characteristic parameters of a converter circuit within one commutation period after a fault occurs in AC/DC hybrid system;
• determining a characteristic frequency of the circuit according to the conduction state information and the characteristic parameters;
• determining a virtual grounding resistance according to the characteristic frequency and the characteristic parameters;
• determining fault areas according to the virtual grounding resistance;
• protecting the LCC-HVDC lines based on the fault areas, turning off current in the LCC-HVDC lines when the fault areas are located within the LCC-HVDC lines.