Fault Location and Calibration of Multi-Terminal DC Ring Network Based on Traveling Wave Redundant Information

Traditional single-ended traveling wave fault location is sensitive to velocity uncertainty, complex topologies, and variations in the equivalent impedance of converter stations. This paper proposes a fault distance calibration method based on the fusion of traveling wave redundant information and inverse weighting: multiple sets of initial distance estimates are formed using wave fronts arrival times measured at multiple terminals. These estimates are then calibrated through inverse weighting fusion according to the error sensitivity of each redundant observation, thereby suppressing errors caused by wave velocity deviations and structural inhomogeneities. Simulation verification using PSCAD/EMTDC for a four-terminal VSC-MTDC loop network demonstrates that this method reduces dependence on precise wave velocity measurements while enhancing the accuracy and robustness of DC loop network fault location.