Parameter identification method with applications to traveling wave head in VSC-HVDC

In voltage source converter based high voltage direct current (VSC-HVDC) system, the zero-sequence network at both ends of the DC line can be equivalent to a parallel capacitor, which reduces the slope of voltage traveling waveform to difficultly identify the traveling wave head with electrical quantities. A method is proposed to identify the arriving time of traveling wave head via judging the sudden changing time of the calculated zero-sequence capacitance. The method is used to locate fault points in the DC line of VSC-HVDC system of 100 km, and the absolute location error can be limited within range of 200 m. The theoretical analysis and simulations show that the proposed method is reliable and accurate to identify the arriving time of the traveling wave head, especially, it is immune from the slow change of electrical quantities and the frequency dependent characteristics of DC lines and suitable for high resistance grounding cases.