Current Injection Technique Based One-Terminal Fault Location Method for Flexible DC Distribution Network

Fault location methods of the flexible DC distribution network can locate the fault accurately and are of great significance for clearing the faults quickly. The existing fault location methods are summarized and their advantages and disadvantages are analyzed in this paper. A current injection technique based one-terminal fault location method is proposed. When a pole-to-ground fault or a pole-to-pole fault occurs, the faulty line will be isolated by the DC circuit breakers. After that, a location module is put into the terminal of the faulty line to form a second-order oscillation circuit. The damping coefficient and the characteristic frequency of the capacitor discharging current are extracted using the Prony algorithm. The fault distance and fault resistance are calculated from the parameters of this fault circuit. The parameters of the location module are designed to keep the characteristic frequency lower than 100Hz which can avoid the influence of non-uniform distribution of the line inductance. The validity and accuracy of the proposed method are verified by comparing with other existing methods.