With the increase of the penetration level of distributed energy

the proportion of installed traditional generators in power system is decreasing

and the stability of the system is suffering from more and more serious threat. Virtual synchronous generator(VSG)can provide inertia and damping support for the system and thus becomes a research hotspot in recent years. However

when VSG is connected to the grid

not only the low/medium voltage line impedance

which is resistance-inductance characteristic

can cause power coupling

but also the large power angle can cause power coupling. The power coupling mechanism caused by line impedance and power angle is analyzed. By establishing the response model of the power and frequency when the VSG is connected to the grid

it is found that the large increase of the active power reference or the severe decrease of the grid frequency will cause the power angle to become larger and the reactive power control will have significant deviation. A novel power decoupling control strategy for VSG based on adaptive virtual impedances is proposed. Finally

a simulation model of VSG connected to grid is designed by using PSCAD/EMTDC

and the correctness and validity of the proposed power decoupling control strategy are verified.