bonsoir
l’histoire du Kosovo vient de faire l’objet d’un texte transmis lors des tests de Shortwave Radiogram
en MFSK32 reçu aujourd’hui sur 9400KHz à16H00 UTC…désolé si c’est en anglais
[i][size=85]From Deutsche Welle:
Clocks in Europe are running late because of the Kosovo conflict
7 March 2017
Fabian Schmidt
Clock radios and timers on microwaves and stoves have gotten out
of sync in Europe in recent weeks. The reason: Coordination
problems between the power grid operators of Kosovo and Serbia.
Since mid January power companies in Kosovo and Serbia have
failed to mutually balance their electricity grids in the case of
irregularities. According to the grid codes of the European
Network of Transmission System Operators for Electricity
(ENTSO-E), they are obliged to maintain a mean frequency of 50
hertz (oscillations per second) and help each other out if
necessary.
But in reality, the mean frequency was lower most of this year.
The reason: The operators did not talk to each other. This
resulted in power deficits of the larger regional grid control
area Serbia, Macedonia, Montenegro, also known as the « SSM
Block ».
Lower frequency means less energy
All in all the, frequency deviations amount to the equivalent of
113 Gigawatt hours (GWh) in lost energy. That is roughly the
daily production of a larger scale brown coal power plant.
There are 36 member states in ENTSO-E with interconnected power
grids, ranging from Spain to Norway and from Turkey to the
British Isles. The recent reductions of the frequencies have
affected 25 of the member-states.
This resulted in a situation in which clocks which are dependent
on the power grid, such as clock radios or clocks built into home
appliances like stoves or stereo systems, have lost time. Since
the beginning of the problems in January it has amounted to
roughly six minutes.
Better to lose six minutes than suffer a blackout
To maintain the required frequency of 50 Hertz, the electricity
grid uses a primary control. This is a technical mechanism which
makes sure that power deviations will be quickly balanced by
drawing additional energy from batteries or other sources in
neighboring power grids - until additional power plants have been
activated and reached their full power levels.
If balancing doesn’t work, a five-step plan takes effect: If the
frequency drops below 49.8 hertz, the first step takes effect,
and additional primary regulation sources must be activated.
If that isn’t enough to stabilize the network, operators may have
to disconnect selected consumers or parts of the grid. In the
fifth step, when the frequency drops below 47.5 hertz, a total
blackout can occur.
A continuous frequency decline, as we’re seeing now, had never
previously happened in the joint European grid.
« I don’t know of any other case where a partner has not met the
rules over a longer period of time, » says Christian Rehtanz, a
professor at the Institute for Energy Systems at the Technical
University of Dortmund. « The situation is new and needs to be
fixed. »
Rehtanz says he could imagine separate areas of the grid having
to be disconnected - but he also warns of the consequences.
« The dilemma is that we should not risk triggering a blackout in
any region. On the other hand, the political actions of some
should not endanger the secure operation of the whole system. »
A technical, but also political, problem
ENTSO-E has called on its member states to solve the problem with
urgency, both in a technical and a political sense. Some states
should not be put into a position where they have to provide
« primary regulation energy » (the energy used to balance short
term irregularities in the system) over a longer period of time
in order to compensate for regional deficits.
But, there is no reason for panic, either. Frequency deviations
of up to one percent (49.5 to 50.5 hertz) for up to 44 hours per
year are normal, says Jutta Jansen. She’s a professor of electric
power supply with renewable energies at the Technical University
of Darmstadt. « This shows that the frequent but minimal
deviations we’ve seen recently do not appear critical for
operating the power grid. »
And the fact that the clocks are running late is « an unpleasant,
but not really dangerous, situation, » she says. In the long run,
the lost time could actually be compensated for by raising the
frequency again slightly above 50 hertz.
So maybe it’s better to wait before resetting your clock -
otherwise, you might have to set it back again later.
[/size]
[/i]
dw.com/en/clocks-in-europe-a … a-42867061
See also:
rferl.org/a/balkan-dispute- … 86085.html
Clt