Power-Sharing between Grid-Forming and Grid-Following Inverters

Power-sharing between grid-forming and grid-following inverters in an islanded microgrid is a challenging task Specifically, the decentralized droop-based power-sharing is difficult to achieve when a grid-forming inverter contributes to regulate the voltage and frequency of the microgrid. This article proposes controllers for the grid-forming and the grid-following inverters, which ensure proportional power-sharing as well as regulate the voltage and the frequency. Both controllers use active power-frequency and reactive power-voltage droops. Additional secondary loops and secondary forward paths are added to the controller of the grid-forming inverter and the grid-following inverter, respectively, to ensure simultaneous voltage and frequency regulation and power-sharing. The efficacy of the proposed controllers is verified through experiment results in a multi-inverter testbed.