Low-frequency Oscillation in Power Grids with Virtual Synchronous Generators: A Comprehensive Review

Virtual synchronous generators (VSGs) are effective solutions for low-inertia issues caused by the high penetration of inverter-based resources. However, low-frequency oscillation (LFO) is introduced as a side effect owing to the simulated swing equations in the VSGs. Although LFO has been widely researched in synchronous generator-dominated power systems, the mechanisms and mitigation strategies of VSG-related LFO have been found to be quite distinct. This study presents a comprehensive review of this emerging issue. First, the different causes of VSG-related LFO are sorted, and a unified explanation from the perspective of power-angle dynamics is provided. Then, control strategies to suppress VSG-related LFO are classified, and the advantages, disadvantages, and applicable scenarios of each method are compared. Finally, several topics for future research are discussed, including the aggregation of massive VSGs, wide-area monitoring and source detection, and advanced suppression strategies.