A Fault Location Method for Modern Distribution Network Based on Fault State Estimation by Hybrid Measurement

The micro-phasor measurement unit (PMU) provides a solid measurement foundation for further upgrades in distribution automation. However, the current limited number of PMUs in the power grid cannot meet the demands of traditional fault location methods in distribution networks. To address this issue, a fault location method based on hybrid measurement state estimation is proposed, integrating PMUs with smart meters and utilizing a multiple state estimation method based on virtual nodes. First, the measurement information from PMUs and smart meters is input into the fault state estimator through equivalent transformation. Then, the network is divided into different regions using PMUs. Fault currents are calculated based on the state estimation results to narrow down the fault search area and reduce computational complexity. To identify the fault location within the region, multiple specific fault topologies are created by setting additional virtual fault nodes, and multiple state estimations are performed to compute the weighted measurement residuals used to determine the fault location. Finally, simulation tests are conducted in a real-time digital simulation (RTDS) system. The results show that the proposed method can accurately and effectively locate faults under different fault scenarios and has good robustness against measurement errors.