On May 1, 3:55*am, John Rumm wrote:
On 01/05/2013 03:38, The Natural Philosopher wrote:









On 30/04/13 22:26, 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....

yes, but they are still separate issues.

separate issues, but codependent if you prefer.

--
No. The generators are driven at constant speed. They are linked
magnetically with every other generator in the country.
As demand increases, the torque and excitation are increased.
If demand exceeds availabilty then the voltage falls/is allowed
to fall. No more torque can be applied, no more excitation
can be applied or the machine will overload by too much
current in the stator.

Al of the above is near impossible with wind turbines which
run most efficiently at different speeds for different wind
speeds. which is why their output is first rectified and then
inverted to mains frequency. This overcomes a major
control problem