Transient Angle Suppression and Voltage Support Control for VSG Based on Virtual Circuit Elements

Insufficient reactive voltage support and power angle divergence are critical issues threatening the stable operation of virtual synchronous generators (VSG) under faults. However, existing research lacks comprehensive transient control methods considering both voltage and transient angle stability and fails to explore transient enhancement strategies after fault current limiting. In this paper, a fault circuit model for VSG considering current limiting is established, revealing the impact mechanisms of different Q-U controller on voltage transient support in phasor diagrams. Subsequently, the influence of fault current limiting on transient angle stability is discussed. Based on this, a transient control method for VSG considering both voltage support and transient angle stability is proposed. This method utilizes virtual capacitance and virtual resistance to modify Q-U and P-f controllers, respectively, to achieve reactive voltage support and transient angle suppression under faults. Furthermore, the application of the proposed method under fault current limiting is discussed, and the idea of fault current redistribution is proposed to enhance voltage support strength and reduce fault instability risk. Finally, hardware-in-loop experiments validate the correctness and effectiveness of the theoretical analysis and proposed.