The 4 German Transmission System Operators (4GTSO) set out minimum requirements regarding connection to the grid for data centers. These requirements are in line with those published by ENTSO-E on 22 December 20251 and can be understood as a supplement to the requirements of VDE-AR-N 4120 and VDE-AR-N 4130 in their current version. In this contribution, the 4GTSO present the relevant technical requirements for data centers. They also outline the experiences and challenges encountered by technical stakeholders. This provides the academic community with valuable insight into the development of grid connection requirements and can support the development of simulation models and the performance of power system studies.

In the event of a short circuit, data centers switch to island mode to maintain ongoing processes. Without specific requirements, they only return to grid parallel operation after a few minutes. From the perspective of the transmission grid, this corresponds to a permanent outage, resulting in a significant reduction in the local grid load. The resulting power imbalance jeopardizes system stability, through frequency instability, impermissible voltage surges, an exacerbation of voltage angle divergence, and an impairment of (N-0) security.

• To avoid disconnection from the grid, data centers must meet certain requirements. These include the ability to ride through temporary voltage changes (fault ride-through, FRT) and robustness against large frequency changes (rate of change of frequency, RoCoF).
• After a grid fault, data centers must demonstrate a rapid (and ramped) power recovery to grid parallel operation as soon as the grid voltage has reached the regular operating limits.

Lack of appropriate specifications for operating behaviour, the active and reactive power consumption of data centers can vary considerably, particularly in the context of AI applications.

• Therefore, load volatility must be limited in the short term to ensure system stability and the undisturbed operation of parallel systems.
• Data centers need to provide or demand reactive power within their technological capabilities to compensate for voltage changes due to changes in operational load.

The increasing penetration of power electronic equipment in the transmission grid increases the risk of undesirable interactions and the excitation of resonances. AI data centers in particular exhibit periodic and pronounced power changes (“load induced forced oscillation”), which can lead to undesirable repercussions. Negative repercussions on the following effects must be limited:

• Inter-area and local oscillations of generator groups,
• Sub-synchronous interactions with neighboring power plants and converters (SSTI, SSCI),
• High-frequency interactions.

Reliable evidences on compliant behavior and the safe local and regional integration of data centers are required based on suitable simulation models (RMS and EMT models, harmonic model), verification, and studies.