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

Abstract

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 Ω or

lower ground resistance is distinguished. Under the occurrence

of faults with 500 Ω 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.