An Efficient DC System Crosstalk Fault Detection and Localization Approach via Variable Bridge

To address the problems of existing DC crosstalk fault detection methods, including complex procedures, difficult implementation, and potential insulation hazards, this paper proposes the crosstalk fault detection and location method based on variable bridge. First, by periodically switching the busbar-to-ground resistance through a variable-bridge circuit in one DC system, a low-frequency AC signal is injected into one busbar, while the bus voltage of another DC system is synchronously detected. If this low-frequency AC signal is present, it can be determined that a crosstalk fault exists between the two DC systems; this signal injection method avoids the insulation safety hazards caused by the coupling capacitor injection method. Subsequently, a method of alternating injection and detection between the two system sections is adopted to locate the crosstalk branch. Finally, the dual-frequency method is introduced; namely, AC signals of two different frequencies are injected and the impedance of the crosstalk loop is measured separately, and a system of two equations is established to solve for the crosstalk resistance. The simulation experiment results show that, whether positive–positive pole crosstalk or positive–negative pole crosstalk occurs, this method can accurately identify the crosstalk branch and measure the crosstalk resistance.