Coordinated disturbances haunt grids worldwide. Here’s how researchers solved the mystery.

A team of researchers in Germany, led by Dirk Witthaut, solved the mystery of coordinated power drops on power grids worldwide. The culprit was found to be hydropower plants, whose vibrations could cause ultra-low frequency oscillations (UFLOs) that disrupt the grid's frequency. This was determined through computer modeling of a hydropower plant control system on the Scandinavian grid. The researchers were able to recreate conditions that could generate a resonance that peaked on the same frequency as the observed power drops every 60 seconds, matching the pattern seen in data from Europe, Australia, the US, and Malaysia.