Welcome to the third report this year of the data acquired with the PQopen measurement network.
Summary
In the summary, the 1s-mean value of the mains frequency is evaluated.
| Statistics | Value and occurance |
|---|---|
| MIN | 49.8651 Hz (2026-03-29 22:00:26 CET) |
| 1% Percentile | 49.9442 Hz |
| MEAN | 49.9996 Hz (~ 21 seconds slow) |
| 99% Percentile | 50.0546 Hz |
| MAX | 50.1256 Hz in CH/Solothurn (2026-03-23 10:54:51 CET) |
Daily Mean
The daily mean can give you an overview of the „accuracy“ of the grid control and their effect on grid synchronized clocks.
Rate of Change of Frequency (ROCOF)
The ROCOF is an indicator for potential events and the steadiness of the frequency. The higher the value, the more disturbances are at work (oscillations, transients…).
Inter-Area oscillations
The inter-area oscillations is a long-known phenomenon resulting from the wide area of interconnected countries. In Spain, two modes can be detected, the east-center-west and the east-west mode.
High Oscillation Amplitude in the Netherlands
After my post from 1st of March, some of you contacted me to also have a look in the Netherland’s grid. Only two weeks after first contact, the measurement was ready. Right from the start, the 3.5 Hz oscillations detected in northern-west germany, were much intense in the Netherlands.
Other Abnormalities
Events
Below, there are several graphs, each representing a detailed time series plot of cycle-by-cycle frequency as well as 10-cycle moving average, phase angle difference and voltage magnitude.
Some readers had the idea of automatically analyzing these traces and doing some sort of „triangulation“ for estimating the area of event root. I had no time in february to give it a try, but it is on my list. If someone of you is interested of trying this, please use the archived data or the API for more recent events.
Thank you for reading the whole report!
Yours, Michael