Enhancing power system stability with GFM-BESS - a case study on a real incident in Denmark

This paper investigates the application of Grid-Forming Battery Energy Storage Systems (GFM-BESS) to enhance power system stability, using large-scale simulations of a real incident in Denmark’s eastern transmission system (DK2). On August 6, 2020, DK2 experienced a sequence of transmission line faults that drastically reduced system strength, disconnected key assets such as HVDC link and synchronous condenser (SynCon), and posed a risk of system collapse. The event highlighted the need for faster and more flexible grid support. To evaluate the potential of GFM-BESS, detailed electromagnetic transient simulations with vendor-specific models replicated system topology, operational scenarios, and fault sequences. Two configurations were compared: the original setup with SynCons and a modified system including GFM-BESS. Results show that GFM-BESS stabilizes voltage and improves fault recovery more effectively than SynCons, even at smaller capacities. Its near-instantaneous reactive power response enables rapid voltage restoration and mitigates active and reactive power oscillations. Performance depends on installation site, GFM-BESS capacity, and control tuning, emphasizing the importance of strategic deployment. Overall, GFM-BESS demonstrates superior adaptability and resilience, offering a robust solution for the secure transition to converter-dominated power systems.