Improving Protection of Low-Voltage Networks with High DER

Increasingly, customers are connecting distributed energy resources (DER) to LV networks, which are widely used for serving concentrated loads in dense urban areas. Additional DER generation can offset the demand peak and even back-feed the primary feeder. Moreover, most newly added DER are inverter-based resources (IBR), which have unconventional behaviors during faults and disturbances. Current LV network protection systems are designed to clear faults on the medium voltage feeder by detecting excessive reverse current (or power). The combination of DER back-feed and IBR unconventional fault response poses a significant challenge to the existing LV network protection philosophy and practice. This presentation will explain research findings on the state of industry practice, needs, and opportunities in LV network protection and control.