Robust dynamic fuzzy-based enhanced VPD/FQB controller for load sharing in microgrid with distributed generators

Microgrid control strategies are mostly accompanied by droop control to ensure voltage and frequency stability, and proportionate power sharing among distributed generation systems. However, conventional droop control may cause undesirable voltage and frequency deviations due to impedance mismatch of the DG feeders, different ratings of the DG units, and complex configurations (loop or mesh networks). To circumvent the above issue, it is necessary to design a dynamic approach for an improved power sharing without sacrificing any voltage and frequency deviations with optimum regulation and stability. In this paper, three conventional drooping topologies, namely as real power and reactive power drooping (PQ drooping), virtual impedance drooping, and voltage real power drooping or frequency reactive power boosting (VPD/FQB), are deployed and compared to investigate their efficiency and stability in the power sharing issues in low-voltage islanded microgrid system. Based on the simulated results, it has been observed that the conventional VPD/FQB topology is superior in load sharing over the other two topologies. However, the conventional VPD/FQB offers certain drawbacks in steady-state and dynamic stability under nonlinear and unsymmetrical load conditions. For further enhancement of the conventional VPD/FQB topology, a novel dynamic fuzzy logic controller (DFLC) is proposed in this study. Simulation results from the IEEE test system in MATLAB environment validate the performance of the proposed DFLC-based VPD/FQB scheme under different operating conditions as compared to conventional VPD/FQB approach.