Accurate Power Allocation of Multienergy Storage Island DC Microgrid Based on Virtual Power Rating

For isolated island dc microgrid connected with multidistributed energy storage, the initial state of charge (SOC) of energy storage is inconsistent and the power distribution of distributed energy storage unit (DESU) may be affected by the mismatched line impedance. Therefore, an adaptive droop coefficient control method based on virtual power rating is designed, which can quickly equalize SOC and eliminate the influence of mismatched line impedance. In the proposed control strategy, the arctangent function is introduced to combine the droop coefficient with the SOC of the energy storage unit, and the characteristic of the arctangent function is used to ensure the fast SOC equilibrium and limit the adaptive adjustment range of the droop coefficient. Considering the actual operating point together with the virtual operating point of the energy storage unit, the virtual power rating is used to construct the compensation term, which can automatically eliminate the output power deviation according to the line impedance difference of the DESU. In addition, the stability analysis is given theoretical support for the proposed control strategy. Finally, the reliability and effectiveness of the proposed strategy are verified by the RTLAB experiment.