This paper explores the application of Grid-Forming Battery Energy Storage Systems (GFM-BESS) to enhance power system stability in the large-scale system-wise simulations, using a real-world incident in Denmark’s eastern transmission system (DK2). On August 6, 2020, DK2 experienced a series of faults in transmission lines, which led to a drastic reduction in short-circuit strength, the disconnection of key assets (HVDCs, Synchronous condensers), and a potential risk of system collapse. This event exposed the vulnerability of conventional stability resources like synchronous condensers (SynCons) under weak grid conditions and highlighted the growing need for faster, more flexible grid support solutions in systems with high share of converter-based facilities.

To evaluate the potential benefits of GFM-BESS in such critical scenarios, Electro-Magnetic Transient (EMT) simulations were conducted in the system-level using vendor-specific models to retrieve real-world situations. The incident was replicated in detail, capturing system topology, operational states, and the fault sequence. Two system configurations were compared: the original setup with existing SynCons and a modified version with a GFM-BESS replacement. Furthermore, the study evaluated the effects of different GFM-BESS capacities, installation sites, and adjustments to control parameters to gain insights into effective deployment strategies.

Results show that the GFM-BESS not only stabilizes voltage and damps oscillations more effectively than SynCon but also enhances system resilience with a smaller capacity than SynCon. Voltage profiles recover within seconds after disturbances, and active/reactive power swings are significantly reduced with support from GFM-BESS. The nearly instantaneous and inherent reactive power response of the GFM-BESS plays a critical role in this rapid stabilization. Further simulations confirm that the location of the GFM-BESS installation can have a major influence on system response, with optimal placement delivering better performance on oscillation damping and fault recovery. Increasing the converter capacity of the GFM-BESS further enhances performance, while tuning its control parameters optimizes the balance between responsiveness and stability.

These findings demonstrate that GFM-BESS is superior to SynCon for enhancing system stability with high share of converter-based facilities. Compared to traditional synchronous condensers, GFM-BESS solutions offer rapid and inherent response and thus better voltage support, while being more adaptable to future grid challenges. From a system operator’s perspective, strategic deployment of GFM-BESS can provide an effective approach of future-proofing the grid while enabling a secure and reliable transition to a converter-dominated power system. The study suggests incorporating GFM technology into upcoming grid planning and investment frameworks, particularly in areas where maintaining stability with conventional solutions is less practical.