Abstract: Compared with AC power grid， DC microgrid not only has simple structure and high efficiency， but also can better absorb distributed new energy such as photovoltaic and wind power generation， while it has almost no inertia. The port converter can simulate the charging and discharging characteristics of capacitors when the virtual capacitor control is applied， which can improve the quality of DC voltage and enhance the stability of DC microgrid. However， the mechanism of inertia enhancement under virtual capacitance control is not clear. The problem that how much capacitance can be produced by virtual capacitor control remains to be further explored. Accordingly， analogous to the variation of load sharing by generators in AC microgrid according to inertia， the power regulation at each side of DC microgrid in the initial stage is allocated according to the proportion of capacitance value. And on this basis， the equivalent capacitance calculation method based on virtual capacitance control is proposed to explore the corresponding relationship between virtual capacitor and equivalent capacitor. Finally， the hardware-in-loop test platform in controller level is established to verify the effectiveness of virtual capacitance control， the correctness of the basis for power regulation allocation in DC microgrid and the corresponding relationship between virtual capacitance and equivalent capacitance.

Key words: DC microgrid, virtual capacitance control, power regulation allocation, equivalent capacitance