Enhanced Power Decoupling Strategy for Virtual Synchronous Generator

Power coupling caused by high impedance ratio and nonzero power angle is a crucial issue for virtual synchronous generator (VSG), which may result in output power error, slower power response and even invalid operation. To solve this issue, a novel enhanced power decoupling method by using virtual steady-state synchronous impedance (VSSI) and current dynamic decoupling compensation (CDDC) is proposed. VSSI with the unique characteristic that the value of virtual reactance maintains constant in all frequencies, can solve the power coupling caused by impedance ratio. CDDC can solve the power coupling caused by nonzero power angle in the fastest way by the designed compensation in inner current loop. The reshaped output impedance characteristics are also analyzed in detail. Then, by state-space modelling and analysis, it is proved that, compared to the traditional methods, the proposed method can improve the dynamic performance and enhance the system stability further. Finally, the results of comparative experiments demonstrate that the proposed method can solve the power coupling problem more effectively and improve the dynamic and steady-state responses of active power and reactive power.