Discovering the Source of Disturbances
For years, power grid operators around the world have faced a mysterious phenomenon consisting of a slight drop in grid frequency that occurs with extreme precision every 60 seconds. This recurring pattern, observed across different continents from Europe to Australia and the United States, has raised concerns among experts due to its potential impact on grid stability and equipment safety.
A research team led by Dirk Witthaut from the Forschungszentrum Jülich in Germany took on the task of solving this puzzle. After ruling out traditional hypotheses related to hydroelectric turbines, the team focused on devices that operate with precise timing and concluded that Uninterruptible Power Supply (UPS) systems in data centers are the primary culprit for these disturbances.
Why Does This Fluctuation Occur?
UPS systems, especially those used in large data centers, rely on checking their State-of-Charge periodically every minute. Since these devices are connected to the internet, their internal clocks are synchronized with high precision. When thousands of devices in multiple data centers perform this check at the exact same moment, their cumulative effect creates a tangible disturbance in the electrical grid frequency.
Data derived from the Irish grid confirmed this hypothesis; data centers consume a significant portion of the country's energy, and it was observed that the intensity of the minute-long frequency drop doubled from 3 millihertz in 2016 to more than 20 millihertz in recent years.
What Does This Mean for Grids?
Although a drop of 20 millihertz may seem small within the grid's tolerance capacity (which usually reaches 200 millihertz), its accumulation with other loads could push the grid toward states of instability or power outages. Furthermore, these disturbances may cause long-term damage to sensitive equipment.
The researchers recommend that manufacturers add a "randomization" feature to the State-of-Charge check timing in UPS systems, rather than having them operate on a fixed schedule. The team also warned that the problem could worsen with the proliferation of Internet of Things (IoT) devices that might exhibit similar behaviors, which calls for regulatory interventions and global software updates to ensure the stability of energy infrastructure in the future.