VSC-HVDC Traveling Wave Protection Based on the First Current Extremum of the Non-Fault Pole

To improve the protection sensitivity under high-resistance faults in VSC-HVDC (Voltage Source Converter based High Voltage Direct Current Transmission) grids, a novel traveling wave protection scheme is proposed. Firstly, by analyzing the non-fault pole current, the characteristics of the FCENP (First Current Extremum of the Non-Fault Pole) are revealed; it is reduced by the fault resistance and increased by the fault distance and the reflected wave. Then, based on the FCENP, indistinguishable faults are divided into different fault zones. The protection scheme is proposed, with the corresponding auxiliary criteria and setting strategies suggested under different topologies. The protection scheme is with high sensitivity to identify the high-resistance fault and is suitable for different topologies while guaranteeing the protection speed. The protection performance is validated by a four-terminal VSC-HVDC grid on the PSCAD/EMTDC platform.