Loadability Assessment of Droop-Controlled Islanded Microgrids: Integration of Droop Control Functions Under Unbalanced Loading

One key factor in the operation of droop-controlled islanded microgrid (IMG) systems is its maximum loadability. In this paper, the effect of droop controllers on loadability of IMGs is studied. Moreover, the effect of different unbalanced conditions, droop functions, reactive droop coefficients, and also inverse droop on the IMG loadability are taken into account. The proposed model is examined on an unbalanced 38-bus and IEEE 906-bus ac IMGs. The findings substantiate that for conventional and inverse droop cases, respectively, reactive (Q-droop) and active droop functions (P-droop), due to their intentional voltage deviation, highly affect the IMG loadability.