25th Wind Integration Workshop 2026, Porto

Grid‑Forming Control of DC‑Connected Offshore Wind Farms: Requirements, Technical Limitations and Contribution to Instantaneous Reserve

Sebastian Höhn, Georg Deiml, Konstantin Jakob, TenneT TSO GmbH, Germany

Tobias Neumann, Pascal Winter, Katharina Günther, Amprion GmbH, Germany

Since 2019 the German Grid Code includes the requirement of “dynamic voltage support without reactive current specification” and “contribution to instantaneous power reserve”. Both of them define a grid forming (GFM) control function for DC connected power park modules (PPMs) on a very high functional level, without specific details and quantification of GFM functionality.

As the extraction of kinetic energy from a wind park for the instantaneous reserve is highly restricted by aerodynamics, rotor-dynamics and the mechanical loads of the wind turbines, there was a clear need of technical in-depth investigations to consider the limitations of DC connected PPMs providing GFM service. Due to the large number of offshore wind park already in operation and those still to be built, DC connected PPMs do have a large potential to serve the system need for instantaneous reserve in the German and Continental European Synchronous Area.

Considering technical challenges on the one hand and the large potential on the other hand, TenneT TSO Germany GmbH (TTG) had invited to a project independent collaboration with wind industry at the Wind Integration Workshop 2023 in Copenhagen, with the goal of establishing GFM DC connected PPMs. General concepts and actual considerations have been presented within the Wind Integration Workshop 2024 in Helsinki.

In parallel, the technical readiness of HVDC technology to connect and integrate instantaneous reserves from the offshore wind parks has been taken forward in a separate workstream with the HVDC suppliers.

The feedback of the HVDC and wind turbine suppliers based on detailed analyses of technical solutions, system needs and internal studies have been gathered by TTG and Amprion to define a set of requirement for GFM of DC connected offshore wind turbines. The TSOs consider the requirements to be realizable in quantitative and technical terms of grid forming control, as they do consider the limitations, capabilities and characteristics of the wind turbines, being well different to other GFM technologies. Furthermore, with this first generation of GFM wind turbines the mechanical design is unchanged, thus GFM is a pure software solution so far. Subject to this condition, wind industry can stay with its state-of-the-art standard design of grid following wind turbines. Even with this restriction, TTG and Amprion do see a significant contribution to system stability.

These requirements form the starting point for the realization in ongoing and future offshore grid connection projects. In the final paper and at the Workshop, TenneT and Amprion will present the details of requirements for GFM, the steps and studies to be performed in the process of grid code conformity.