Researchers trace worldwide minute-by-minute grid frequency dips to synchronized UPS and battery state-of-charge checks
Researchers led by Dirk Witthaut at Forschungszentrum Jülich identified the cause of ultra-low frequency oscillations (ULFOs) observed every 60 seconds on power grids from Europe to Australia, the U.S. and Malaysia. The investigation was prompted by Germany's largest transmission system operator, Tennet Germany, and initially focused on hydropower turbine resonance, which could not explain the metronomic persistence of the signal. Instrumenting the Jülich campus with more than 80 power quality meters, the team traced the peaks to the transformer serving the battery energy storage system, concluding that internet-synchronized clocks in stationary batteries and UPS devices make them check their state-of-charge simultaneously on the minute. Grid operator data from Ireland, where data centres reached 18% of grid load by 2022, showed the per-minute frequency drop quadrupling from 3 mHz in 2016 to 12 mHz in 2021, with recent dips above 20 mHz. This is a power-system reliability and equipment-stress issue, not an attack or a vulnerability: no threat actor, malware or CVE is involved, and current amplitudes remain well inside Ireland's 50 Hz grid tolerance of ±200 mHz.
Detalhes técnicos
Frequency must stay within a narrow band for orderly grid operation; large or misdiagnosed oscillations can trigger improper operator response and blackouts, and sustained sags can damage power plant equipment, particularly hydropower turbines. Modelling of a hydropower plant control system on the Scandinavian grid reproduced a once-per-minute resonance but not its indefinite persistence, pointing instead to a clock-driven cause. Individually, a single state-of-charge check is imperceptible on the wide grid; aggregated across synchronized fleets of UPSes serving data centres and grid-scale batteries, the combined draw becomes measurable. The team also detected periodic power fluctuations from IoT devices including a smart oven and Raspberry Pi clusters, suggesting the phenomenon could broaden as such loads multiply.
Remediação
The researchers recommend that UPS and grid-scale battery manufacturers randomize (jitter) the state-of-charge polling schedule instead of aligning it to the exact minute. The correction is a simple software/firmware change, but patch uptake is a limiting factor: a recent study cited in the article found fewer than 3% of IoT devices run the latest firmware. Regulators may need to mandate the change, and because the pattern is global, lasting mitigation will require international coordination.
Linha do tempo
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Researchers trace worldwide minute-by-minute grid frequency dips to synchronized UPS and battery state-of-charge checks
ler a análise desta fonte ocultar
Researchers led by Dirk Witthaut at Forschungszentrum Jülich identified the cause of ultra-low frequency oscillations (ULFOs) observed every 60 seconds on power grids from Europe to Australia, the U.S. and Malaysia. The investigation was prompted by Germany's largest transmission system operator, Tennet Germany, and initially focused on hydropower turbine resonance, which could not explain the metronomic persistence of the signal. Instrumenting the Jülich campus with more than 80 power quality meters, the team traced the peaks to the transformer serving the battery energy storage system, concluding that internet-synchronized clocks in stationary batteries and UPS devices make them check their state-of-charge simultaneously on the minute. Grid operator data from Ireland, where data centres reached 18% of grid load by 2022, showed the per-minute frequency drop quadrupling from 3 mHz in 2016 to 12 mHz in 2021, with recent dips above 20 mHz. This is a power-system reliability and equipment-stress issue, not an attack or a vulnerability: no threat actor, malware or CVE is involved, and current amplitudes remain well inside Ireland's 50 Hz grid tolerance of ±200 mHz.
Technical Details
Frequency must stay within a narrow band for orderly grid operation; large or misdiagnosed oscillations can trigger improper operator response and blackouts, and sustained sags can damage power plant equipment, particularly hydropower turbines. Modelling of a hydropower plant control system on the Scandinavian grid reproduced a once-per-minute resonance but not its indefinite persistence, pointing instead to a clock-driven cause. Individually, a single state-of-charge check is imperceptible on the wide grid; aggregated across synchronized fleets of UPSes serving data centres and grid-scale batteries, the combined draw becomes measurable. The team also detected periodic power fluctuations from IoT devices including a smart oven and Raspberry Pi clusters, suggesting the phenomenon could broaden as such loads multiply.
Remediation
The researchers recommend that UPS and grid-scale battery manufacturers randomize (jitter) the state-of-charge polling schedule instead of aligning it to the exact minute. The correction is a simple software/firmware change, but patch uptake is a limiting factor: a recent study cited in the article found fewer than 3% of IoT devices run the latest firmware. Regulators may need to mandate the change, and because the pattern is global, lasting mitigation will require international coordination.