On 01/05/2013 11:26, John Rumm wrote:
On 01/05/2013 08:18, harry wrote:
On Apr 30, 10:26 pm, John Rumm wrote:
On 30/04/2013 06:15, harry wrote:

On Apr 29, 11:46 pm, The Other Mike
wrote:
On Mon, 29 Apr 2013 14:24:18 +0000 (UTC),
(Andrew

Gabriel) wrote:
This is for EU-wide product supply.
UK had historically aimed to maintain +/-0.1Hz for no other reason
than CEGB had controls good enough to do so.
Much of the rest of the EU aims for +/-1Hz, and there may be some
EU synchronisation zones even outside that range.
The appliances will have to cope with the worst case.

There was someone on another group in the past few months, maybe
uk.railway? I
think the poster was possibly German, and they were claiming that
on the German
grid, the system frequency during the loss of 1.5 - 2GW of
generation (this
was a one trip, one site event) with a system loading of 50GW was
about 0.05Hz.

Yes you read that right zero point zero five hertz. So that's a
larger loss than
the Sizewell B Longannet incident of 2008 that resulted in a
frequency of around
48.8Hz. No, I didn't believe it either!

Not got any measurements in Germany but the frequency moves about
in Italy about
the same as the UK.

--

Frequency, load and efficiency are separate issues.

No, frequency and load are closely related....

As any generator is in parallel with others, the speed/frequency,
cannot change.

The logic does not follow. Since "the others" can and do change
frequency as a group, the frequency of any individual one *must* also
change so as to remain in sync.--

Indeed they keep the long term average frequency equal to 50.0000Hz but
the spot frequency is dependent on actual load. Notably they run faster
at night when the load is light - this used to be mildly annoying in the
bad old days when telescopes used mains synchronous motors.

--
Regards,
Martin Brown