Voltage Regulation of Microgrid Inverters in Grid-Following and Grid-Forming Mode

As the global demand for renewable energy and distributed generation increases, the role of distributed energy resources (DERs) to regulate voltage robustly becomes increasingly important, and scenarios where system topology changes add complexity leading to variation in regulatory capability. When microgrids island from the bulk grid, they lose the reactive power compensation of Volt/VAR control (VVC), but operate at smaller scale voltage levels and tend to integrate a greater diversity of DERs, which may allow for more precise regulation of voltage with less latency. A case study comparing the voltage regulation of a live, microgrid inverter and its effect on power factor from several real islanding scenarios is presented, along with a homologous analysis of four VVC parameter configurations. We found that the Category-B inverter had a greater ability to regulate voltage in grid-forming mode, and that for optimal voltage regulation in grid-following mode, the inverter should use configuration settings with a reference voltage approximately 2.08% higher than nominal and use 22% of its maximum apparent power nameplate rating as an upper bound for reactive power compensation.