Towards grid code revisions and fault behavior insights for modeling grid-forming converters

Grid-forming (GFM) converters are pivotal technologies for future power systems, characterized by a high share of variable energy resources (VER) such as photovoltaics and wind turbines. Unlike grid-following converters (GFLs), GFM converters form the voltage and frequency independently from the external grid, enabling them to operate autonomously and support the grid. However, their integration to the grids comes with significant challenges, particularly regarding the limited fault current contribution, their fault ride-through (FRT) capabilities and their impact on current protection schemes. Their operation can complicate fault detection and relay coordination. This paper reviews the state-of-the-art FRT strategies, their compliance with emerging grid code, and the impact of grid-forming converters on fault current contribution and current protection schemes. Moreover, this paper discusses the need for grid codes revision and the development of standardized testing protocols to address these challenges. Insights from pilot projects and the vital role they play to bridge the gap between the theoretical investigations and real-world applications are also discussed. Finally, key challenges and future research directions are also introd uced to contribute to the widespread implementation of GFMs in the future power systems.