Electromechanical oscillation suppression method in multi-VSG system based on droop-VPSS control

• A small-signal model is formulated for a grid-connected multi-VSG parallel system to investigate low-damping mechanisms and electromechanical oscillations. • A droop-VPSS control is proposed to suppress the power/frequency coupling oscillation and drive the VSG to quickly adjust the power output to suppress electromechanical oscillations and enhance the overall damping capacity of the system. • Compared to adding a single damping controller, the proposed droop-VPSS controller coordination method exhibits a more significant oscillation suppression effect. The large-scale integration of power electronic equipment, mainly based on virtual synchronous generator (VSG) technology, has a significant impact on power system damping and inertia, which may introduce active power oscillation issue. This paper proposes a method for suppressing electromechanical oscillations in multi-VSG systems, analyzing the impact of parametric coupling on system stability through small-signal modeling. First, a small-signal model of a multi-VSG parallel system is established to analyze the weak damping characteristics and the electromechanical oscillation. Second, an electromechanical oscillation suppression method is proposed for multi-VSG parallel systems, which combines droop control and VPSS. Finally, the influence of the inertia coefficient, damping coefficient and droop coefficient of the proposed method on the system stability is verified by simulations.