Voltage Balancing Strategy for Grid-Forming Inverters Based on Unbalanced Loads

When unbalanced loads are connected to grid-forming inverters, negative sequence components and harmonics are introduced. These not only reduce the power factor and power conversion efficiency of the inverters, increase system energy loss, but also cause fluctuations in the output voltage of the inverters, deteriorating the quality of electric power and potentially causing interference or damage to connected devices. Therefore, to ensure stable system operation, this paper proposes a voltage balancing strategy based on resonant control for grid-forming inverters under unbalanced load conditions. This strategy involves incorporating resonant control into the outer voltage loop to suppress the double-line frequency component, effectively eliminating negative sequence voltage and maintaining balance in the output voltage of the grid-forming inverter; and through simulation, it has been verified that the proposed strategy achieves excellent results in improving unbalanced voltage and system efficiency.