As the penetration rate of renewable energy increases

the grid-connected converters (GCCs) need to have grid-forming capabilities. However

existing virtual synchronous generator (VSG) control lacks the interaction with dc-side units

which may lead to reduction inrenewable energy utilization efficiency or dc-link voltage collapse. This paper quantitatively analyzes the relationship between DC inertia and AC inertia. To solve the problem of limited inertia of dc-link capacitor

a VSG control strategy based on virtual DC capacitor is proposed

which enables the DCMG to provide virtual inertia equivalent to the inertia time constant of traditional synchronous generator for the AC grid. The proposed VSG control strategy can also effectively coordinate the dc-link voltage control. Simulation and experimental results validate the functionality and effectiveness of the proposed control strategy.