Enhancing Microgrid Stability and Performance Using Dynamic Q - V Controller for VSG

The active power droop gain determines the stability margin of a Microgrid (MG). Increasing this margin enhances MG's transient performance and robustness. However, prior research on virtual synchronous generators (VSGs) has focused on improving MG stability through either parameter selection or P-ω control loop adjustments, jeopardizing the dynamic characteristic and neglecting the outer voltage control loop impact. This paper proposes a practical approach to enhance MG stability and performance by embedding a dynamic reactive power derivative controller into the VSG static voltage control loop. The proposed derivative controller is structured using local measurements without adding a new derivative controller, thereby avoiding the complexities of derivative controller implementation in the real world. The controller is designed through small-signal stability to maximize MG marginal stability. The paper also provides design guidelines for selecting the proposed controller's parameter depending solely on time-domain simulation reflection, thereby eliminating the need for time-consuming small-signal models in large systems. Furthermore, the effects of the dynamic voltage control loop on power response, rate of change of frequency (RoCoF), and voltage profile are investigated. The results show significant improvements in MG stability and reactive power oscillations damping while maintaining desired RoCoF levels.