The claim
European grid frequency dropped sharply. Europe narrowly avoided a blackout on December 12th.
Our conclusion
No, the network frequency was within completely normal parameters. At 49.9 Hz we don't have to worry for a long time, the control mechanisms work.
Electricity is like blood, energizing the body of our civilization. Like the veins in the human body, the electrical network is widely branched. The large overhead lines are the arteries, the lines in households are the capillaries in which the electricity is consumed. But the power grid beats with many hearts, in many different places. As different as these hearts are - huge hydroelectric power plants on the Rhine, small PV systems on the roof of your home - they all beat to the same rhythm. The pulse: 50 beats per second, 50 Hertz, the mains frequency. At least here in Europe.
++ The first alarm situation was there: European network frequency dropped drastically ++ The European interconnected network was closed on December 12th. only narrowly missed power shutdowns ++ Unusual frequency drop in the European interconnected network ++ Europe narrowly missed the blackout ++ Oh oh, big problems in the network at the moment! ++
Alarmism on the Internet: Should paranoia be stirred up here?
___STEADY_PAYWALL___
Mains frequency: 50 Hertz ± fluctuations
Our power grid operates at a frequency of 50 Hertz because the turbines that generate the electricity rotate 50 times per second. At least in theory. If more electricity is required than is currently being generated, the frequency drops. If there is less demand, it increases. On the European electricity exchange, electrical energy is traded in 15 minutes. However, this is far too rough to be able to react to the constant fluctuations in supply and demand. Therefore, there are other automatic control mechanisms that ensure that the frequency remains within a narrow spectrum.
The deviations from the target value of 50 Hertz must never be too large, otherwise sensitive electrical devices can be damaged.
Benjamin Schäfer (currently Karlsruhe Institute of Technology) on PV Magazine
However, “sensitive electrical devices” do not mean the usual household appliances, which are usually very insensitive to frequency fluctuations. Many power supplies, such as those in laptops, can easily handle 50 to 60 Hertz (the frequency in the US power grid). “Power plants and converters that are optimized for a small frequency range are particularly problematic,” explains Benjamin Schäfer .
Why 50 Hertz of all things?
Turbines generate alternating current. A rotating magnet creates an oscillating magnetic field that alternately attracts and repels charged particles in a surrounding coil. The higher this AC frequency is, the faster turbines have to rotate. This results in higher loads and greater wear. Slow frequencies, on the other hand, had a visible disadvantage with the light bulbs used previously: the light flickers. The 50 Hertz is the compromise from the early days of electrification that has prevailed in Europe. In other areas of the world, particularly on the American continent and parts of Asia, a network frequency of 60 Hertz has become established.
Fluctuations in grid frequency and countermeasures
We have heard that excessive frequency fluctuations damage power plants and converters. These are also the actual reason for so-called blackouts, large-scale failures in power grid operations that result in further failures in the public infrastructure. If, for example, large power plants go offline unexpectedly due to an accident or important lines fail due to natural disasters, this can lead to undersupply or oversupply in individual parts of the power grid, which is expressed in corresponding relatively large frequency changes.
What is relatively large? It is always a question of scale and the scales used. Here are three examples of real-time network frequency information available on the Internet:
If we have these scales in front of us and then read statements like...
“The frequency fell to 49.9 Hz within a short time,” “The grid frequency normally oscillates stably between 49.98 Hertz and 50.02 Hertz” (both blackout-news.de ), “Although every available coal and gas power plant is connected to the grid "The frequency fell to 49,900 Hertz that night - an unusually strong drop in frequency" ( pleiticker.de ), "If the network frequency drops below 49.8 Hz, the first power cuts can therefore occur" (FB group Friedrich Merz - party chairman of the CDU Germany )
...then the alarm bells start ringing. But are 49.9 Hertz really that unusual? No they are not. Let's take a look at this in detail.
Exactly 50 Hz would be the desired ideal. At values between 49.99 and 50.01 Hertz nothing happens at first. This dead band allows measurement errors of up to 10 millihertz. If the grid frequency exceeds this narrow spectrum, so-called “control energy” is used. If the frequency is too low, power storage units distributed in the network are emptied; if it is too high, they are filled. This happens automatically and to a defined extent for deviation.
From ±10 mHz to 200 mHz, the control power (RL) used is activated proportionally from 0% to 100%. In the long term, a maximum of ±180 mHz deviations are permitted; in the short term, there may be deviations of ±200 mHz. The permitted frequency range in normal operation is 49.8 Hz to 50.2 Hz.
Dr.-Ing. Thomas Gobmaier on netzfrequency measurement.de
“Normal operation” is in the range of 49.8 to 50.2 Hertz. Only if there are larger deviations will further power plant output be switched on or off. On the one hand, 49.9 Hertz is a completely normal spike and, on the other hand, it doesn't happen all that often, as this histogram shows:

The control range from 49.8 to 50.2 Hertz becomes even clearer in the following representation of real-time data. “In contrast to the other network frequency displays on these pages, which only cover a range of +/-80mHz, the entire possible frequency range is displayed here. This is intended to make it clear how much 'air' actually still exists and the deviations look much less dramatic," writes Dipl.-Ing. (FH) Markus Jaschinsky on his website netzfrequency.info.

Above 50.2 Hz, power plants that do so quickly (e.g. PV systems) are taken off the grid; in the 49.0 to 49.8 Hertz range, others are switched on in the same way. Only when the frequency falls below 49 Hz does “load shedding” become necessary. Things become critical for the network at 47.5 Hertz. When the first power plants begin to switch off or go offline to prevent damage to the technology, the frequency continues to fall and a domino effect occurs - a large-scale blackout that must be avoided at all costs.
Case study: January 8, 2021
If disruptions occur in the network, attempts are made to find and isolate the cause. Hans Urban took a close look at a major incident in the European interconnected grid and describes in the PV magazine how exactly countermeasures were taken.
On January 8th, 2021 at around 1:05 p.m., the network frequency quickly dropped sharply across the entire UTCE network. Due to power plant and transmission line failures in Romania, there was a shortfall in electricity supply of around 3.6 gigawatts. Within a few seconds, the network frequency dropped from approximately 50.03 to 49.74 hertz. When the 200 mHz limit was exceeded, the criterion for the “immediate activation of power reserves” was suddenly reached, but further steps towards “automatic load shedding” (gradual power shutdowns of 12.5% of the network at a time) at 49 Hz were a long way away .
In order to avoid the error spreading and, in particular, effects on the entire European UCTE network, the entire southeastern European network was disconnected for a certain period of time and then reconnected to the rest of the network (re-synchronized) about an hour later after the errors had been resolved. The normal situation could therefore be returned very quickly without any further impact on the rest of the European network. The only indication of the incidents is the frequency drop that was measured everywhere at the same time.
Grid frequency in Europe drops to 49.75 Hertz - the result is system splitting
CONCLUSION
Fluctuations in the frequency of the power grid can be a problem. They arise when more or less electricity is fed in than is consumed. In Europe there is a large interconnected network (as in many other regions of the world), which means that balance must be ensured in the overall network as well as in sub-areas. However, there are some control mechanisms and a step-by-step plan on how to deal with this, which is precisely regulated the VDE FNN
Initially, decoupling of sub-grids or certain power plants will be considered before one has to think about shutdowns. There have been some major incidents in the past, but the way they responded shows that they are actually very well prepared. So the fluctuations that are alarmingly discussed on social media are harmless. Up to 49.9 Hz is within the everyday fluctuation range, up to 49.8 Hz can be compensated for with “control energy”. “Load shedding” only begins at 49 Hz, a (controlled) blackout occurs at 47.5 Hz.
Not enough about the topic of network frequency and blackouts? Mimikama's Tom Wannenmacher sheds light on the likelihood of a blackout . Hans Urban explains the function of electricity storage in the event of a fault PV Magazine His colleague Daniel Seeger explains the role that electricity trading plays in the strain on the networks. And why clocks sometimes run slow can also be related to the network frequency.
If you are interested in real-time values of the network frequency, you will find them here: curves from the last hour , curves from the last 3 days . And I would like to recommend the following to (aspiring) paranoids - who beat at 50 Hz: real-time warning when the frequency falls below 49.8 Hz via Telegram channel .
Sources: PV Magazine , VDE , UCTE , illwerke vkw on, netzfrequenzmessung.de , netzfrequencies.info , gridradar.net , frequenzmessen.de (offline)
More fact checks: No, this is not a “5G park bench”!
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