Dynamic State Estimation-Based Protection of Distribution Systems with High Penetration of DERs

The integration of distributed energy resources (DERs) into distribution systems has brought immense changes and challenges. Fault currents can now flow bidirectionally and the levels can vary widely. As a result, correct protection operation based of legacy distribution current-based relays cannot be guaranteed. Dynamic state Estimation-Based Protection (EBP) is one of the schemes proposed to protect such active distribution network. EBP identifies internal faults while ignores external faults by checking the consistency between redundant measurements and the protection zone model, irrespectively of direction or level of fault currents. However, one issue is encountered when applying the EBP in distribution systems: the unavailability of measurements at load and DER branches in the protection zone (reduced measurement set). The influence of reduced measurements is investigated by case studies and several selected protection methods are compared with the EBP. The results show that the EBP has greater sensitivity and selectivity compared to other protection methods.