A Novel Passive Injection Method for Single-Phase Grounding Fault Line Selection in Distribution Networks Using Distributed Zero-Sequence CTs

To address the issues of slow speed and low accuracy in fault line selection for distribution networks, this paper proposes a novel method based on distributed zero-sequence current transformers (CTs) with passive high-frequency carrier signal injection. The characteristics of zero-sequence currents during single-phase grounding faults in distribution networks are analyzed. The method involves modulating high-frequency carrier signals on the secondary side of traditional zero-sequence CTs, coupling them back to the primary side for passive injection, transmitting the signals to the substation bus, and extracting and processing the zero-sequence carrier signals at the receiving end. Faulty lines are identified by comparing the amplitude and phase of the carrier signals. A simulation model is built on the Matlab/Simulink platform, and the results demonstrate that this method achieves rapid and accurate fault line selection for small current grounding systems.