Power grids twitch every minute: UPS self-tests solve the puzzle

Why it matters

UPS units and battery storage are becoming more common as grids take on more renewable energy and operators rely on batteries for flexibility. Their built-in routines, designed to make each device reliable, can add up to a measurable effect at grid level when they are synchronized. Understanding the mechanism gives grid operators and device makers a concrete starting point for judging whether the effect is harmless or worth addressing, for example by staggering test timing.

The available information does not detail how large the twitch is or whether any countermeasures are planned. What is clear is that the minute-by-minute pattern, long unexplained, now has an identified origin in the self-test routines of everyday power electronics.