Re: communicate with the grid... mmmmm
"Have you heard of the speed of light, speed of a wave front through a conductor and propagation delay? ."
Thanks for that. I'm sorry to say it, but for anyone (including me) that wasn't sure before, you have now confirmed that you are rather confused about the basic underlying science involved here. I think it used to be A level physics, dunno whether it still is.
"That is the phenomenon which ensures frequency cannot be the same at every point in the grid instantaneously"
Dearie me.
At any given instant in time, at any given point on the network, you can measure voltage but you can't instantaneously measure frequency. And because of propagation delay of an AC signal, the instantaneously measured *voltage* of a continuous AC signal is going to be different at different places on the network. That's basic physics.
On the other hand, frequency cannot be measured instantaneously. It just can't. It's derived from the time it takes for a complete cycle of something - in the case of 50Hz UK grid frequency, it takes 20milliseconds (more or less). If you want a more accurate frequency measurement, typically you need to measure for longer. Not instantaneous.
The speed of light in vacuo is around 3E8 metres/s, call it 300 km per ms, so in one cycle of 50Hz (20ms) the voltage will travel 6000 km or so. Actually it's somewhat less than that, because we're looking at electricity in a cable rather than in a vacuum. Let's maybe call it 4000 km or so in a 20ms cycle.
On that basis, for all practical purposes the grid frequency is the same across the UK. If it wasn't, there'd very quickly (a few ms or less) be huge circulating currents (e.g. between a generator at 49.8 Hz and a generator at 50.0 Hz) which would massively disrupt grid operations.
"strategically placed generation units around the UK grid to operate in 'Frequency Control' mode where they essentially act as regional 'clocks' to stabilise the >>local<< frequency."
So close and yet so far. There is no >>local<< frequency, only the national frequency. There is local instantaneous voltage, but it isn't greatly relevant to the original discussion here - frequency response.
The fast response frequency regulation generators contribute power locally, allowing the transmission systems to stabilise the *national* frequency, when there is a fast change in demand (or supply). A similar system applies to slower changes in demand (or supply).
"I have no intention trawling through the rest of your essay "
Clearly. Readers who want to know more could perhaps look at what National Grid have to say about frequency stabilisation (though like much of the 'modern' electricity industry, sadly it's more about commercial contracts than about engineering):
http://www2.nationalgrid.com/uk/services/balancing-services/frequency-response/
"I just resort to practical knowledge."
What exactly was your job at Gridco? It doesn't sound like it involved engineering fundamentals.
Biting the hand that feeds IT
