Influence of Inverter-Based Resources on Microgrid Protection Part 2: Secondary Networks and Microgrid Protection S SECONDARY NETWORKS ARE DEPLOYED WHEN exceptionally high-reliability electric service is required for specific loads. Secondary network protection makes extensive use of the fact that the available fault currents in such systems are typically very high. Also, most faults in secondary networks must be isolated from both sides, which requires some special considerations. Today, microgrids are also being deployed as a means of increasing power system resilience on radial circuits. Many microgrids are energized exclusively by inverter-based resources (IBRs), either all the time or under certain operational conditions. The protection of IBR-sourced microgrids By Michael E. Ropp and Matthew J. Reno © SH U Digital Object Identifier 10.1109/MPE.2021.3057952 Date of current version: 19 April 2021 may/june 2021 1540-7977/21©2021IEEE T TER STO C K . C O M / L E OW O L F ER T ieee power & energy magazine 47