Suppressing power oscillation based on VSG

To stabilize the voltage and frequency, virtual synchronous generator (VSG) control of renewable energy interfaced inverter is recommended. However, traditional VSG control will lead to unbalanced three-phase current and power oscillation under unbalanced grid voltage. To solve these problems, an improved control strategy is proposed. Firstly, problems with traditional VSG control strategy under unbalanced grid voltage and its differences from traditional grid-connected inverter control strategy are demonstrated. Secondly, under dq coordinate system, the balance current VSG control strategy is used to obtain the reference positive sequence current commands which can decrease negative sequence current. Current is transformed to be balanced. Thirdly, to damp power fluctuation, negative sequence current is calculated. Based on above The current inner control loop is designed. Finally, the validity and effectiveness of the proposed control strategy is verified through the Matlab/Simulink simulation results.

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