On Wed, 1 May 2013 20:35:24 +0100, Ian Jackson
wrote:

In message , Andy Champ
writes
On 30/04/2013 20:51, Ian Jackson wrote:
In message , Andy Champ
writes
Yes. And?

If you get an increased load, surely you can maintain speed by
reducing the excitation current - can't you?

This will result in a reduction of generator output voltage.

That's the idea. To reduce power consumption by reducing voltage, but
_without_ changing the frequency. Apparently the UK grid can't do it.

If you lower the voltage at the power station (instead of allowing the
frequency to drop), and somewhere down the line there are automatic
re-adjustments to try to maintain the correct voltage, more current will
be drawn from the power station. If the power station again reduces its
voltage, the same thing will happen again. Presumably it's all a careful
balancing act involving both voltage and frequency.

The generator at the power station and the 400kV, 275kV and 132kV transmission
networks all run at or very close to their nominal voltages, always.

The adjustment for voltage us made on the distribution networks, usually on the
secondary side of transformers having 132kV on their primaries.


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