Improving the Synchronous Stability Control Strategy of Virtual Synchronous Generators

Abstract

The microgrid dominated by new energy has small inertia and weak damping, while a virtual synchronous generator (VSG) is an effective means to enhance inertia and damping to improve the stability of the microgrid. However, it also introduces power angle oscillation problems similar to that of synchronous machines. This paper is based on the current inner loop and voltage outer loop control of the three-phase LCL inverter. It introduces the virtual inertia and damping coefficient of the virtual synchronous generator, achieving a good grid connection effect. While a significant change in active power occurs, the system can lose synchronization and stability. Therefore, the paper proposes an improved synchronization stability control strategy for virtual synchronous generators by introducing a frequency-proportional integral feed-forward link in the reactive power loop to suppress power angle oscillation and improve system synchronization stability. Theoretical analysis was conducted on the synchronous stability of the improved control strategy in case of sudden changes in active power load. The effectiveness of the strategy was verified through simulation.