Single-phase ground fault line selection method in active distribution networks based on high-voltage inverter injected signals

Fault line selection is a major problem of distribution networks. Selection of the fault line in distribution networks is increasingly becoming difficult due to the connecting of abundant new energy resources. A fault line selection method based on injected characteristic signals by the inverter was proposed in this study to increase accuracy of fault line selection. Under fault of distribution networks, the proposed method selected fault line by changing the modulation strategy of the inverter for a short time and injecting characteristic signals. A typical simulation model of active distribution networks was constructed to analyze different earth faults in distribution networks. Accuracy of this model was verified by simulation analysis. Results demonstrate that characteristic signals at different zero-sequence current measuring points are significantly different after signals are injected. Accordingly, the fault line during faults with 500 Omega or lower ground resistance is distinguished. Under the occurrence of faults with 500 Omega or higher ground resistance, the characteristic signal injection method based on an inverter has better energy value and can increase accuracy of line selection effectively compared with the traditional energy method. This study provides certain references for fault line selection in distribution networks based on inverters.