An Algorithm for Fault Detection in HVDC Transmission Lines

In this paper, an algorithm is proposed for fault detection in HVDC lines using transient characteristic of the fault component of voltage and current measured on one side of the transmission line. In the proposed algorithm, when the starting unit of the protection system confirms the occurrence of fault, the fault voltage, and current correlation level is used to determine the fault direction and then by using high-frequency harmonic component of the fault current the fault is detected in the protective zone. Finally, by removing the coupling between the currents of positive and negative poles the faulted line is distinguished from a healthy line in the DC bipolar system. The simulation results for a variety of faults verify the validity of the proposed method.