Terminal capacitor compensation based stability design for DC microgrids

This paper investigates the detailed elements of a DC microgrid that might cause instability, and proposes a stabilizing guidance based on the passive stability criterion. For illustration purpose, the terminal output impedance model of a source side power converter under double loop with droop control is built, and its frequency characteristics are analyzed. It is found that the instant high power absorption from the microgrid might make the source side power converter's output to oscillate. The details of how the circuit and control elements in the source side impact the terminal impedance are illustrated. This paper shows that the stability of plug and play performance of DC microgrid can be guaranteed with the proposed stabilization methods. A Matlab/Simulink model is used to validate the analysis.