ROCOF incident study and stability enhancement by grid-forming technology in Danish power system

To investigate the ROCOF incident, system-level electromagnetic transient (EMT) studies are carried out involving transmission grid-connected vendor-specific models. The system-level

EMT study successfully reproduces the event and is validated against the phasor measurement units. The study highlights the importance of implementing correct frequency and ROCOF calculation in simulation modelling for frequency dynamic studies.

Stability enhancement solution enabled by grid-forming (GFM) battery energy storage systems

(BESS) is further evaluated. GFM-BESS’s inherent behaviour resisting to the change of frequency is evaluated together with an existing synchronous condenser in DK1 via both singlemachine infinite-bus system tests and system-level EMT studies, showing that GFM-based solution can have more flexibility in control design to provide inertial and damping response.

In addition, comprehensive studies are carried out by deploying GFM-BESS to DK1 system, Offentlig/Public by evaluating its performance in ROCOF mitigation in the DK1 incident. Different GFM-BESS parameters are evaluated, including BESS capacity, inertia constant, operating points and deployment location.

Finally, study conclusions are summarized. Remaining challenges to deploy GFM-BESS are discussed for inspiring prospects for future development on analysing and managing stability issues in low-inertia power systems based on a transmission system operator (TSO)’s perspective.