[time-nuts] Daft idea with the National Grid

[Dana Whitlow]

Not daft at all, Andy.  Closely related would be measurements of phase
change between
near the switched load and far away, over a stretch of a few system time
constants.
This would be more challenging, but perhaps doable.

Dana   K8YUM


On Sun, Feb 7, 2021 at 3:44 PM Andy Talbot <andy.g4jnt at gmail.com> wrote:

> The UK has a standalone frequency locked grid supply, nominal 50Hz, which
> typically wanders +/- about 0.15Hz RMS over several minutes , with
> occasional short-lived excursions out to 0.2 or 0.3Hz.  Average number of
> cycles per period generally is normalised to 50Hz after a few days.
> The typical loading for the country ranges over ~25GW to 45GW
>
> Now, I wonder:
> I can probably measure the grid frequency to a few micro Hz   over a period
> of tens of seconds. So I make a continuous recording of this, averaged over
> say 10 second periods.
> Now take a 7kW load (the maximum reasonably possible on a domestic circuit)
> and switch it on and off at intervals of perhaps 10 minutes, precisely
> timed so it can be correlated with the frequency log.  That 7kW load will
> be about 0.2ppm of the average for that for the whole of the UK.    By post
> processing, and some deep correlation covering days worth of cycles of load
> on-off with the frequency, I wonder if it would be possible to see the
> loading, the mean frequency changing by a few uHz.
> Not sure what the time constant of the grid control is, but for* small
> signals* I doubt it can be faster than a few minutes.
>
> There was a serious outage on 9 August 2019 that caused frequency to drop
> below 49.5Hz and initiate automatic load shedding;   that happened over a
> period of a couple of minutes but was a large scale problem.
>
> https://www.ofgem.gov.uk/publications-and-updates/investigation-9-august-2019-power-outage
>
> Andy
> www.g4jnt.com
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