Abstract: Virtual synchronous generator technology can provide virtual inertia for the frequency stability of

microgrid，but there are a lot of asymmetric loads in the operation of microgrid. In order to compensate the

unbalanced load and output three-phase symmetrical voltage and current，an improved control strategy based on

virtual synchronous generator was proposed. An adjustable coefficient λ was introduced into the dual second-order

generalized integrator，so that the positive and negative sequence voltages and currents can be accurately separated from the output three-phase asymmetrical voltages，and the information of voltage and current amplitude，frequency and phase angle can be extracted，the output voltage reaches three-phase equilibrium. The current control adopted a sequential control based on dq coordinate system to balance the unbalanced current output of three phases. Finally，the effectiveness and correctness of the proposed control strategy were verified by comparing the traditional virtual synchronous control strategy with the improved virtual synchronous control strategy in the Matlab/Simulink simulation platform and the HIL hardware in-loop experiment platform.

    Key words: virtual synchronous generator（VSG）；microgrid；asymmetric load；adjustable coefficient；dq

coordinate system sequence control