Enhanced voltage regulation of AC microgrids with electric springs

Intermittent renewable generations can induce voltage instability issues in terms of (i) AC bus voltage variations and (ii) voltage flickers in AC microgrids, which deteriorate the power quality of the critical loads. To address this, the electric springs with capacitive energy storages can be applied to regulate the bus voltages at the points of common coupling (PCCs). In this paper, a novel control method is proposed to enhance the voltage regulation performances of the ES in AC microgrids. The controller is designed to achieve the concurrent compensations of bus voltage variations and voltage flickers. The steady-state model of an ES associated with a non-critical load (NCL) is analytically derived. The design of the controller as well as the small-signal analysis is provided. The experiments and simulations have been performed on a scaled-down 110 V AC microgrid. The results have verified that the proposed control method can effectively realize the aforementioned functionalities.