Experimental Assessment of Parallel Operation of Grid-Forming and Grid-Following Inverters in an Islanded Microgrid

Abstract:
This work presents an experimental validation of the parallel operation of two interconnected inverters within a microgrid that is entirely based on power electronics. The main inverter operates as a grid-forming inverter controlled by the generalized droop control technique, while the second inverter operates in grid-following mode. This research examines how this microgrid configuration accomplishes the regulation of voltage and frequency required by international standards, while operating independent from the main grid, and thus maintains a stable operation. Moreover, the obtained experimental results demonstrate successful synchronization between the two units highlighting the ability of the implemented control techniques to black start, coordinate for parallel operation, and regulate terminal voltage and system frequency. These insights contribute to the further development of different microgrid control strategies and structures.