A hierarchical control approach to improve the voltage and frequency stability for hybrid microgrids-based distributed energy resources

This study proposes a multi-layer interactive control scheme to improve the performance of microgrids (MGs) based on distributed energy resources (DERs). This structure ensures the stability of the four system parameters, including voltage/frequency (V/F) and active/reactive (P/Q) power of the MGs, respectively, due to the correct operation of the defined control layers. In the proposed method, in the first layer, an internal voltage and current controller loop combined in the power droop controller (PDC), duties to adjust the unit V/F, in addition, the MG able to quickly respond to load oscillations is possible. Further, the secondary distributed V/F control strategies based on distributed finite-time control (DFTC) are implemented to modify and restore the control system. In this study, one of the novelties of the proposed method is the use of economically distributed modelling (EDM) in the upper layer above the other layers. The simulation results prove the efficiency of the proposed method strategy (hierarchical control) from two points of view, including voltage and frequency control; as the amplitude of fluctuations of voltage and frequency components has decreased for the units by 0.005 pu to 0.08 pu and 0.005 Hz to 0.018 Hz, respectively