The impedance inside weak current network is large

and when unbalanced loads are connected

it is unable to maintain the stability of its own voltage

resulting in three-phase voltage imbalance and output power fluctuations. Virtual synchronous generator(VSG) technology

as a grid-forming control

can provide support for voltage of the weak current network. However

under the connection of unbalanced loads

the VSG technology cannot maintain output voltage balance. To solve this problem

an improved VSG sequence decoupling control strategy is proposed. Firstly

the principle of three-phase imbalance and power fluctuation in VSG output voltage caused by unbalanced load connection is investigated. Secondly

a dual synchronous coordinate system decoupling(DDSRF) is adopted to separate the positive and negative sequence voltages of the power grid

and a positive and negative sequence control strategy is employed to control the negative sequence voltage component in dq rotating coordinate system. Finally

a VSG simulation model is built and the simulation results indicate that the proposed improved VSG sequential decoupling control strategy can suppress the unbalanced voltage output of the VSGs.