Researchers identify UPS systems as cause of recurring grid frequency fluctuations
Synchronized self-tests performed by battery storage and backup power systems are creating measurable frequency pulses in electrical grids globally.
A research team involving the Jülich Research Centre and RWTH Aachen has solved the mystery of the recurring frequency fluctuations in power grids worldwide. For years, grid operators have observed a pulse-like drop in frequency occurring every minute, a phenomenon that has intensified since 2015. Researchers have now confirmed that the culprit is the diagnostic software embedded in many uninterruptible power supply (UPS) units and battery storage systems.
According to the study, the synchronized behavior stems from devices using Network Time Protocol (NTP) to synchronize their clocks via the internet. Because the systems use a shared timing reference, they initiate diagnostic self-tests simultaneously, causing a collective, momentary drain on the grid. The study analyzed twelve different grids across five continents, finding that this pattern is consistent across large interconnected systems and isolated island networks.
While these fluctuations have not yet posed a significant risk to grid stability, the increasing frequency of these automated devices makes them a subject of interest for grid management. The research highlights the potential unintended consequences of high-precision digital synchronization in critical infrastructure. Experts are now investigating the source of a secondary, weaker peak observed at approximately 100-second intervals.