Dynamic Power Decoupling Control of Virtual Synchronous Generator Based on Improved Virtual Impedance

ObjectivesWhen a virtual synchronous generator (VSG) is connected to a medium and low voltage distribution network, the line impedance exhibits resistive and inductive characteristics, resulting in strong coupling in the VSG output power. This coupling can cause power oscillations and even deviations in the internal power control, affecting power quality and transmission stability. To address these issues, an improved power decoupling strategy based on virtual capacitance is proposed.MethodsBy simplifying the VSG grid-connected model and conducting small-signal modeling, the power coupling mechanism is analyzed to identify key factors contributing to coupling. Based on this analysis, the concept of virtual capacitance is introduced, and an improved control method utilizing virtual capacitance is proposed. Finally, simulations are conducted on the MATLAB/Simulink platform to verify the effectiveness of the proposed strategy.ResultsThe capacitive characteristics of virtual capacitance not only enhance the system’s operational stability, but also correct the output voltage reference, effectively mitigating oscillations exacerbated by power coupling.ConclusionsThe proposed control strategy reduces the interference caused by active power command changes or load switching on reactive power, suppressing strong power coupling during the dynamic process of the system.