Battery self-checks linked to electricity grids’ one-minute rhythm
Researchers traced recurring changes in electricity-grid frequency to synchronized battery self-checks at Germany's Jülich campus. Measurements linked the pulses to systems providing uninterrupted power, and the study connected the pattern with signals seen across continents. The fluctuations have remained below safety-critical levels, but their regular timing matters for hydropower equipment and grid control.
Science··Evening
A steady pulse appeared across electricity networks
A peer-reviewed Nature Energy study linked a recurring grid-frequency signal to synchronized digital control routines. Germany's transmission operator Tennet had seen brief dips every minute in the European electricity grid for years. Measurements across continents revealed a pattern whose timing remained stable over long periods. Grid frequency responds to the balance between electricity generation and consumption, so simultaneous small changes in demand can leave a widespread signal.[1], [2]
The investigation was led by Dirk Witthaut at Forschungszentrum Jülich, a German research centre, with colleagues at the University of Cologne and Karlsruhe Institute of Technology. The team installed measurements at 80 locations in Jülich's campus energy laboratory. Buildings showing the minute-period consumption pattern contained large batteries supplying uninterrupted power. This narrowed the search from the wider grid to specific installations.[2]
Battery checks reached the public grid connection
At one installation, current pulses originating on the battery side could be followed through several transformers to the public high-voltage connection. The manufacturer confirmed that routine self-tests in the battery energy-management system generated the pulses. Internal software schedules and external clock synchronization affect when these checks occur. The evidence links synchronized routines with the international signal, while individual contributors have not been identified in every grid.[1]
There are no binding standards governing the timing of these checks. Witthaut suggests manufacturers may independently have chosen a minute as a sensible interval and scheduled checks at its beginning. Other digitally controlled appliances may contribute comparable patterns. Many devices acting together are needed to describe how a brief local change in consumption becomes visible at the network scale.[2]
Control changes reduced the recurring signal
The measured fluctuations have remained below safety-critical levels. They nevertheless matter for frequency-control requirements and hydropower equipment: turbines briefly slow as demand rises and then accelerate again, increasing wear. Hydropower control responses can also amplify disturbances. In Ireland, the amplitude of the minute-period signal quadrupled between 2016 and 2021. Changes in control requirements in Scandinavia and Australia were followed by lower amplitudes.[1], [2]
The researchers propose spreading self-checks randomly through time and using event-driven control instead of rigid clock intervals. In one investigated battery block, a software update removed the strict periodicity of current peaks. The tests still occurred at discrete times, so the change provided a partial remedy. These measures address the synchronized demand pulses at their origin in device operation.[1], [2]
