A novel traveling wave head identification method in VSC-HVDC based on parameter identification

In the voltage source converter based high voltage direct current (VSC-HVDC) transmission system, traveling wave heads of currents and voltages are affected by fault location and transition resistance, thus are difficult to be recognized. To solve this problem and improve the accuracy of traveling wave head identification, parameter identification method is adopted in the present paper. In the zero-mode network of VSC-HVDC system, dorsal systems at both ends of DC lines are equivalent to parallel capacitors. When an internal fault occurs on the DC transmission lines, identified parameters computed with measured voltages and currents reach the value of equivalent capacitance after a sudden change at both ends, indicating the arriving time of the traveling wave heads. Through identifying the sudden changing time of the identified parameter, the arriving time of the traveling wave head is then recognized. Theoretical analyses and simulation results show that the identified parameter changes suddenly when the traveling wave head arrives at the end of DC transmission lines and equals the equivalent capacitance after that, proving that the proposed method is accurate in identifying the traveling wave head. In addition, the method is immune to the change of fault location and transition resistance and is applicable in AC systems and other DC systems.