Coordinated Control of an Industrial Microgrid with Grid-Forming and Grid-Following Inverters under Weak Grid Conditions

This paper presents a coordinated control framework for an inverter-dominated industrial-park microgrid integrating two units operating as grid-following (GFL) converters with supplementary frequency support which includes frequency–power droop characteristics. Another unit operates as a grid-forming (GFM) unit that establishes the voltage and frequency reference. The framework explicitly accounts for islanded weak-grid conditions, which significantly affect the stability and synchronization of GFL-connected units. The proposed control strategy combines fast primary control with a unified distributed secondary control layer that restores system frequency. The approach is validated through real-time simulation on a Speedgoat platform under a representative disturbance scenario. Results demonstrate improved frequency regulation and robust system performance under islanded or weak-grid conditions, highlighting the effectiveness of the proposed framework for inverter-dominated microgrids.