Grid Forming Converters for Low Inertia Systems—Capabilities and Limitations: A Critical Review
Authors: Qusay Salem; Bayan Bany Fawaz; Rafat Aljarrah; Mazaher Karimi
Extended abstract:
The rapid integration of renewable energy sources into modern power grids has led to the widespread adoption of power-electronics-based interfaces, resulting in power systems increasingly dominated by inverter-based resources. While this transition supports decarbonization goals, it has simultaneously introduced critical challenges, most notably the reduction of system inertia and grid strength, which are essential for maintaining stable and secure operation.
To address these challenges, grid-forming (GFM) converters have been introduced and actively developed as an alternative to conventional grid-following (GFL) converters. Unlike GFL approaches, GFM converters offer enhanced grid support capabilities by directly regulating voltage and frequency, thereby improving system stability and synchronization, particularly under weak-grid conditions. However, despite their promising features, the overall efficacy of GFM technology remains under investigation, and the extent to which GFM converters can replace or complement traditional GFL converters is still an open question.
This article aims to bridge this gap by providing a comprehensive and critical review of the current state of GFM converter technology. It revisits and synthesizes recent advances in the literature, offering a structured evaluation of both the capabilities and inherent limitations of GFM converters in comparison to conventional approaches. The review covers key aspects including converter topologies, control strategies, and their performance in addressing small-signal and large-signal stability challenges, as well as their ability to enhance grid synchronization and transient stability.
Furthermore, the article provides an in-depth analysis of the dynamic behavior of GFM converters under fault conditions, with particular emphasis on fault ride-through (FRT) capability. This includes a detailed discussion of grid code requirements, state-of-the-art FRT control methods, and post-fault recovery performance. Finally, the paper highlights critical challenges, identifies open research directions, and provides forward-looking recommendations to support the reliable integration of GFM converters. Overall, this work offers a timely and comprehensive reference for advancing the deployment of resilient, low-inertia power systems.
