Reduced-order proportional resonant controller for grid-forming converter in asymmetric microgrid

As microgrid configurations grow increasingly complex, stability and power quality challenges arise, particularly under asymmetric operating conditions. This paper proposes a reduced-order proportional resonant controller for grid-forming converters to address these issues. By replacing traditional quasi-proportional resonant controllers, the novel design integrates two first-order controllers with conjugate characteristic roots to independently regulate positive-sequence and negative-sequence components, enabling precise suppression of imbalance-induced disturbances. The study begins by analyzing a grid-forming converter-based microgrid model to quantify the destabilizing effects of negative-sequence components. The formulation of the reduced-order proportional resonant controller is then detailed, emphasizing its ability to decouple sequence components and enhance negative-sequence component attenuation. Experimental and simulation results validate the controller’s efficacy, achieving up to 80% reduction in voltage imbalance while improving transient response times compared to conventional methods. The proposed approach offers a high-performance solution for stabilizing asymmetric microgrids.