Review on small-signal stability of multiple virtual synchronous generators

Abstract

The extensive incorporation of renewable energy sources into the power grid has resulted in a loss of system inertia due to power electronic devices that lack physical inertia, which presents difficulties for frequency stability. Furthermore, the high degree of uncertainty surrounding renewable energy production can significantly affect the power system’s small-signal stability. Virtual synchronous generator (VSG) can emulate the operational characteristics of traditional synchronous generators (SG), providing inertia support to ensure stable system operation. However, the extensive parallel integration of VSGs into the grid introduces new instability factors. This paper focuses on the small-signal stability issues of parallel VSGs. First, small-signal models of the single-machine and multi-machine VSG are established, analyzing its stability issues from a mathematical perspective. Second, the paper details the primary analysis methods for small-signal stability, which are divided into two categories: the state-space method and the impedance modeling method. Third, the paper examines the factors that affect small-signal stability of VSG. Next, several methods to enhance the small-signal stability are reviewed. Finally, the prospects of VSG’s small-signal stability are discussed.