Battery self-tests cause minute-by-minute power grid dips worldwide
Researchers led by Dirk Witthaut at Forschungszentrum Jülich traced a recurring, 60-second dip in grid frequency to battery storage systems and uninterruptible power supplies that run power checks at the same time each minute. The team found the pattern across grids on five continents; it is not considered a safety risk, but researchers say the fluctuations add to wear on hydroelectric turbines.
Bottom line — In Ireland, the signal quadrupled between 2016 and 2021; randomly staggering battery checks could reduce it.
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Researchers identified the cause by measuring electricity use at 80 locations on the Jülich campus, then tracing the signal from a UPS through transformers to a 110 kV grid connection.
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The study found that time-synchronised control software can make otherwise small power checks happen together, creating a measurable demand spike.
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The pattern has grown in parts of the British and Scandinavian grids since 2015, reaching a peak in 2020, according to the Nature Energy study.
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Researchers say hydropower controls can amplify the oscillation, but cannot explain its long-term timing across different grids.
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A manufacturer issued a software update that removed strict periodicity from one battery block studied; its self-tests still run at fixed times.
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The study says the source of a weaker oscillation with a period of about 100 seconds remains unclear.