Modern power grids are increasingly challenged by the lack of inertia caused by the high penetration of renewable energy sources (RES). This low inertia leads to reduced frequency stability and greater vulnerability to disturbances. To address this issue, various virtual inertia (VI) provision strategies have been proposed to emulate inertial behaviour using power electronic converters and advanced control techniques. However, the existing literature reveals two major research gaps. First, there is no unified understanding of VI classification frameworks, as many studies have used diverse categorizations and often treated the Virtual Synchronous Machine (VSM) and Virtual Synchronous Generator (VSG) as equivalent concepts, leading to conceptual ambiguity between grid-forming (GFM) and grid-following (GFL) approaches. Second, most previous research has examined one or a few VI control technologies in isolation, without providing a comprehensive cross-technology comparison that evaluates their relative suitability and dynamic performance under varying conditions. This review addresses these gaps by proposing a new classification framework, which distinctly differentiates between the VSM, VSG, and Synchronverter concepts, while also emphasizing both inertia provision and inertia emulation aspects. This refined framework enhances the understanding of how various VI-based converters contribute to grid stability through either the active production or the imitation of inertial response. Furthermore, the paper provides a structured and comparative review of VI strategies across multiple renewable energy applications—including electrolyzers, electric vehicles (EVs), battery energy storage systems (BESS), high-voltage direct current (HVDC) systems, wind turbines (WTs), and solar photovoltaic (PV) systems—based on their control architectures, frequency response capabilities, and integration potential in future low-inertia grids. The outcomes of this study aim to support researchers and system operators in selecting and developing appropriate virtual inertia control (VIC) methods for maintaining frequency stability in evolving power systems.

Publisher Copyright: © 2025 The Author(s)

Peer reviewed