Reduced-Order Model Based on Equivalent State Variable in Grid- Forming Virtual Synchronous Generator with Improved Transient Damping Control

Reduced-order model and transient damping control of grid forming virtual synchronous generator (GFM-VSG) have attracted attention for less computational cost, simpler analysis and system stability improvement. In this article, equivalent state variables on the basis of high- order differential equations are generated from the power coupling and enhanced VSG control loop. Dominant degree analysis as an effective identification method is involved for less dynamic error of the reduced-order model, which is tested by active power response and eigenvalues analysis. Afterwards, an improved transient damping control are proposed for a zero active power steady-state deviation without affecting droop behaviors under grid frequency step change. Noticeably, the expected damping support and active power responses are achieved with the proposed control, which can be implemented with different parameters. A guide on parameter selection is also provided through eigenvalue analysis. Finally, a qualitative and quantitative comparison with damping methods proposed in numerous other studies are provided to illustrated the good antidisturbance ability and adaptability, theoretical analysis and experimental results validate the accuracy and robustness of the proposed reduced-order model and improved transient damping control.