Battery backup clocks are making power grids pulse every 60 seconds
One-minute frequency disturbances from synchronization in power systems
A Fourier analysis of grid-frequency data from 12 power systems on five continents reveals a strikingly regular oscillation with a period of exactly one minute. The culprit: clock-synchronized control routines in battery-based uninterruptible power supplies, which create periodic demand peaks that propagate up to the transmission level. The pattern is growing in amplitude in several grids, adding wear to hydropower turbines and prompting stricter load-frequency control rules. Because the mechanism is generic to any digitally controlled device running on external timing signals, the authors argue it can be fixed at the source through better control design.
The identified synchronization mechanism is not specific to UPSs or battery systems, but reflects a general property of digitally controlled devices operating with external timing signals or periodic software routines.