To meet Denmark’s national energy ambition of achieving carbon neutrality by 2050, the share of renewable energy generation—particularly wind and solar—must increase signifi-cantly, while conventional fossil-fuel-based synchronous generators are gradually phased out. This shift poses considerable challenges to the secure and stable operation of the power system. In particular, the absence of traditional synchronous machines reduces both voltage strength and inertia, limiting the grid’s ability to maintain voltage and frequency stability during disturbances. In recent years, grid-forming (GFM) control technology in power elec-tronic devices has emerged as a promising solution to address these challenges, drawing increasing attention and application across the power industry.

To accelerate the deployment of GFM technology in the Danish power system, the Danish transmission system operator (TSO), Energinet, launched the “GFM Deployment” project in 2023. In collaboration with leading industry vendors, this initiative aims to assess the readi-ness level of GFM products currently available on the market, identify technical constraints in their behavior and performance, and ultimately support the formulation of well-grounded technical requirements for their integration. As part of this effort, EMT models of GFM-enabled devices—including wind turbines, PV plants, battery energy storage systems (BESS), and STATCOMs—have been tested and integrated into a comprehensive EMT model of the entire Danish power system to evaluate their dynamic performance and grid-support capabil-ities under extreme yet realistic system conditions.

This paper focuses on one of the project’s key studies: the application of a GFM STATCOM in the context of the real-world DK2 2020 incident. The incident, which occurred in the eastern Danish grid (DK2), involved sequential short-circuit faults on two 400 kV transmission lines, ultimately leading to a network split at 400 kV, the tripping of a synchronous condenser, and the blocking of an HVDC link. In our study, the original synchronous condenser in the system is replaced with a GFM STATCOM, and the system’s response to the same disturbance is ana-lyzed. Various device configurations—such as reactive power capacity and voltage control integrator constants—are also tested to assess their impact on system stability. The results show that the GFM STATCOM can effectively prevent system instability in scenarios like the 2020 incident. Furthermore, it achieves a better stabilizing effect with significantly lower reactive power capacity compared to the original synchronous condenser.

This study demonstrates the potential of GFM STATCOMs for improved performance in fast reactive current support and voltage stabilization relative to traditional synchronous conden-sers. Unlike idealized single-machine-infinite-bus test cases, the analysis is based on wide-area full-system EMT simulations, offering practical insights into real-world system behavior. The findings highlight the critical role of GFM control technology in enhancing grid voltage strength and maintaining voltage stability in future power systems dominated by renewable energy sources.