Multi-terminal Synchronous Measurement Strategy for Low Current Ground Fault Location in Distribution Networks with Distributed Power Sources

To address the challenges of complex fault characteristics in distribution networks caused by high penetration of distributed generation (DG) and the insufficient tolerance of traditional fault location methods to high-impedance and communication disturbances, a small-current grounding fault location strategy based on multi-terminal synchronous measurement and graph convolutional networks is proposed. This method constructs an inverter-type DG Norton equivalent model considering the dynamic characteristics of phase-locked loops to quantify the impact of weak-fed current on sequence network parameters. It employs IEEE 1588v2 transparent clock technology combined with sliding window time-stamp correction to achieve microsecond-level hard synchronization in harsh communication environments. By extracting transient zero-sequence energy spectra using generalized S-transform and mapping them to graph node attributes after dimensionality reduction via kernel principal component analysis, the strategy inputs a two-layer graph convolutional network to mine topological spatial correlations for fault section identification. Hardware-in-the-loop tests demonstrate that the strategy maintains over 90% location success rate under extreme conditions such as 1000Ω high-impedance grounding and 30% packet loss rate, while meeting the rapid-response requirements of distribution automation with end-to-end delay compliance