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from the you're-not-just-bored:-the-wall-clock-IS-slow dept.
Electric clocks on continental Europe that are steered by the frequency of the power system are running slow by up to 5 minutes since mid-January according to a news release from the European Network of Transmission System Operators for Electricity ('entsoe'). The transmission system operators (TSOs) will set up a compensation program to correct the time in the future.
Many electric clocks rely on the transmission system frequency to provide a source that minimises long-term drift. Quartz crystals have good short term stability, but dreadful long term stability, so plant and machinery that requires power to be turned on or off at a specific time each day without maintenance over a long period historically used clocks slaved to the power-system frequency, which is kept long-term stable by the system operators to prevent problems in power generation and transmission across national and supra-national grids - for example, attempting to switch supplies to generators that are not synchronised to the grid frequency can severely damage the generator.
It is normal for transmission system operators to allow the frequency to drop slightly at periods of high demand, thus slowing clocks, but usually, the frequency is increased during periods of low demand to ensure the long-term average frequency remains stable.
(Score: 4, Informative) by BsAtHome on Tuesday March 06 2018, @10:42PM (5 children)
A higher degree of load will slow the generator (drag) and therefore reduce the line frequency. To increase the transfer of energy you need to "push" the voltage/current curve, which must be done by leading the curve and that means pushing the frequency upward.
The trick is to keep a constant frequency, which is a hell of a job because most of the EU is interconnected and runs synchronized. Just, for a moment, imagine the problems you have in a synchronized system when there is 2000...2500 km between endpoints; the phase @50 Hz is reversed at that distance. That means that pushing at one end will be seen at the other end quite some time later. The next problem is that the transmission lines have a limited capacity. Pushing beyond that capacity will trip a breaker, generate hell and may cascade.
So, if one (outer) edge has too little capacity, then the other systems cannot push back hard enough or they will trip an intermediate line. Therefore, the frequency will drop due to higher demand than possible supply. Otherwise you must take the edge off the synchronized system, which is a lot more problematic than you might think.
(Score: 2) by DannyB on Tuesday March 06 2018, @10:59PM (2 children)
Stupid speed of light is to blame for needing to build generation plants somewhat close(er) to the load than across the continent.
The lower I set my standards the more accomplishments I have.
(Score: 4, Interesting) by BsAtHome on Tuesday March 06 2018, @11:04PM (1 child)
It is actually much worse... the phase relation changes more rapidly in practice because there are many intermediate stations. And yes, the speed of light is a harsh and unforgiving mistress.
The phase is not a problem as such, but the group-delay is, which makes the control-system much more complex to keep stable.
(Score: 3, Informative) by NewNic on Wednesday March 07 2018, @01:00AM
Electricity in wire* doesn't travel at the speed of light. Just something approaching the speed of light.
* Talking about propagation of the electric field. The electrons move at a much slower speed.
lib·er·tar·i·an·ism ˌlibərˈterēənizəm/ noun: Magical thinking that useful idiots mistake for serious political theory
(Score: 2) by Grishnakh on Tuesday March 06 2018, @11:02PM (1 child)
Sounds like they need to not be as interconnected, at least with AC transmission lines, and perhaps instead use HVDC to join different systems or regional grids.
(Score: 0) by Anonymous Coward on Wednesday March 07 2018, @01:00AM
HVDC seems to be the choice for water based connections, and also becoming the norm for new land based ones as well as adapter between regions.
https://en.wikipedia.org/wiki/List_of_HVDC_projects#Europe [wikipedia.org]
https://en.wikipedia.org/wiki/List_of_HVDC_projects#Europe_2 [wikipedia.org] (outdated map, only up to 2008, lacking 2015 Spain - France, 2015 Lithuania - Poland or 2010 Denmark - Denmark, see list instead)