Recurring fluctuations across power grids
As artificial intelligence (AI) data centers proliferate, research has found that battery equipment installed to prevent power outages could itself periodically disturb the grid. Software that checks battery condition runs at regular intervals, briefly increasing electricity consumption. The analysis suggests that overlapping checks across multiple devices could affect the wider power grid.
An international research team involving Germany's Forschungszentrum Jülich, the University of Cologne and the Karlsruhe Institute of Technology published the findings in the international journal Nature Energy on October 30, local time.
The researchers analyzed data collected from 12 power grids across 5 continents, including Asia, Europe and North America, with South Korea among the countries studied. Despite differences in grid size and operating methods between countries, small frequency changes recurred at 60-second intervals. The same signal was identified in data collected in South Korea over approximately 3 and a half months.
Grid frequency indicates how closely electricity supply and consumption are balanced. South Korea's standard frequency is 60 hertz (Hz), while most of Europe uses 50 Hz. Frequency falls when electricity consumption momentarily exceeds power plant supply, and rises when supply exceeds consumption.
Battery self-checks identified as a source
To identify the cause, the researchers examined electricity consumption by building at the Forschungszentrum Jülich campus in Germany. All 4 buildings where electricity consumption changed regularly every minute had uninterruptible power supplies (UPS). A UPS is battery equipment that continues supplying electricity to data center servers or hospital equipment during an outage.
Measurements of battery current inside the UPS units showed brief increases every 60 seconds. The manufacturer confirmed that these were caused by regular self-checks performed by battery management software. The resulting changes in electricity consumption extended beyond the buildings, passing through several transformers to a connection point with the 110,000 V high-voltage grid.
“Because multiple devices operate using the same clock, their battery checks can also coincide,” the researchers explained. “Even if the power consumed by each device is small, simultaneous operation can cause electricity consumption to change all at once.”
In Ireland, where data centers have expanded rapidly, the frequency drop occurring at 1-minute intervals increased fourfold, from approximately 0.003 Hz in 2016 to approximately 0.012 Hz in 2021. In 2022, data centers accounted for approximately 18% of Ireland's total electricity consumption. Data center expansion and periodic grid changes thus occurred together.
Staggering software checks
The frequency changes currently observed are not large enough to cause an immediate major blackout. However, repeated output adjustments by generating equipment trying to maintain a constant grid frequency could place cumulative strain on equipment.
As a solution, the researchers proposed staggering software operating times so that batteries do not all perform checks simultaneously. One manufacturer modified its battery management program so that current increases in some batteries no longer recurred at 1-minute intervals.
“As AI data centers and large energy storage system (ESS) installations expand, managing these phenomena will become increasingly important,” the researchers added. “Grid stability can be affected not only by the capacity of power plants and transmission lines, but also by how the software controlling large numbers of batteries operates.”
Reference
Nature Energy (2026), DOI: https://doi.org/10.1038/s41560-026-02144-0
Original Korean article: ChosunBiz
English brief by Korea Wind Intelligence, koreawindintel.com
