High Impedance DC Fault Detection and Localization in HVDC Transmission Lines Using Harmonic Analysis

Fault localization in High Voltage Direct Current (HVDC) transmission systems is still an open issue for further investigation. Detection of high impedance faults in the DC link in which the voltage and current quantities are close to their nominal values, can be a challenge for the existing protection relays especially in the absence of communication link. This paper proposes a decentralized fault localization in the DC link using harmonic analysis of voltage and current profiles at converter terminals. Basically, there is a phase shift between the current and voltage of harmonics produced by converter due to existence of inductance in the DC line cable. During the fault, the phase shift between current and voltage is changed. The quantity of phase shift may reflect the location of fault in the DC link. Time domain simulations conducted in PSCAD software demonstrates the efficiency of proposed method.