Influence of DC Voltage Divider Transmission Characteristics on Traveling Wave Protection of HVDC Transmission Lines

Traveling wave protection is the main protection of transmission lines of HVDC transmission system, the accuracy of its operation is related to the safety and stability of system. The calculation of each fault characteristics quantity in traveling wave protection criterion is using measured value of DC voltage divider for protection device. However, it is difficult for DC voltage divider to accurately transmit the signals under each frequency band, which will lead to an error between real value and measured value of DC voltage divider when fault occurs. In this paper, the transfer function of DC voltage divider is derived according to equivalent circuit model of DC voltage divider. The amplitude frequency characteristics and transient characteristics of DC voltage divider are analyzed. A +/- 800kV UHVDC transmission project is built in PSCAD/EMTDC, and the influence on traveling wave protection caused by transmission characteristics of DC voltage divider is analyzed. Finally, it is suggested that the transmission characteristics of DC voltage divider should be considered in traveling wave protection setting.