Daft idea with the National Grid
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
As an amateur radio guy, I can't help wondering whether I could use this as
a very low bit rate channel across the country.
Philip
On Sun, Feb 7, 2021 at 4:44 PM Andy Talbot andy.g4jnt@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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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@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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and follow the instructions there.
Am 08.02.21 um 00:11 schrieb Philip Gladstone:
As an amateur radio guy, I can't help wondering whether I could use this as
a very low bit rate channel across the country.
I have done navigation for tv and phone sats, and the spread
navigation signals are just 20 dB under the MPEG data stream via
the analog transponder. If you back down another 10 or 20 dB, I'm
sure you could disseminate encryption keys or maybe phone without
anybody taking note. And everybody has a TV dish in the right direction.
Search the right one.
Really, I can't imagine that the agencies don't do that already.
Gerhard, DK4XP
On 2/7/21 3:28 PM, Dana Whitlow wrote:
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
If you happen to own something like a steel mill running electric
furnaces or an aluminum refinery, so you can manipulate the load...
Andy Talbot writes:
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 are generally spaking two time constants, the physical and the human.
The physical time constants are probably best understood as water in a
bucket: If you kick it, complex ripples happen but eventually die out.
The timeconstant is generally order of five or ten cycles, unless you
make a short, those are much faster.
Mechanisms: Huge lumps of rotating iron, lots of switch-mode equipment
(including solar, wind mills and HVDC converters), magnetic hysteresis
in really big transformers, Maxwells/Telegraphers equations on long cables.
Unless the grid is on the verge of collapsing, the human time constant
is around 15 minutes. Mechanism: People making mostly financial decisions.
As for your experiment, unless you use a psedurandom pattern, you stand
no chance of detecting a pattern.
I expect you may be able to show a bigger effect than you hypothesize
because the grid is not that "stiff".
Unless your house is right next to a big plant, there are five to ten
transformers between you and the power producer, and all of those "delay"
the phase in response to increasing load.
Your primary singal will therefore be phase-shift rather than frequency-
shift, which means your switching will have to be slow enough that
you can measure the difference between them.
PS: If you get friendly with people at grid control, they will send
you a copy of a pile of laplace equations from hell, which they use
to model the grid, and you can start by plugging your experiment
into them. It wont be pretty.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
Lux, Jim writes:
If you happen to own something like a steel mill running electric
furnaces or an aluminum refinery, so you can manipulate the load...
More scary: Several independent studies have shown that even relatively
moderate bot-nets in the hands of somebody who knows the math of grid
stability would mean no grid stability.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
I'm not convinced they will be impressed by your scheme for ultra VLF
signalling Andy but it'd make a nice Radcom article
On Sun, 7 Feb 2021, 21:44 Andy Talbot, andy.g4jnt@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
time-nuts mailing list -- time-nuts@lists.febo.com
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and follow the instructions there.
On 2/8/21 12:02 AM, Poul-Henning Kamp wrote:
Lux, Jim writes:
If you happen to own something like a steel mill running electric
furnaces or an aluminum refinery, so you can manipulate the load...
More scary: Several independent studies have shown that even relatively
moderate bot-nets in the hands of somebody who knows the math of grid
stability would mean no grid stability.
This is a generalized concern with distributed generation (i.e. rooftop
solar panels on houses), because a bug in the controllers for the line
connected inverter could really screw things up. I suppose there's also
concerns about malicious activity, but fiascos like the NEST
thermostats stopping in winter of 2015/2016 are more likely.
Years ago I recall reading accounts of efforts in the U.S. and perhaps Canada to track down the cause(s) of small but noticeable changes in the frequency of certain regional power grids that seemed to occur at more or less the same time each day.
Mark Spencer
mark@alignedsolutions.com
604 762 4099
On Feb 8, 2021, at 6:48 AM, Lux, Jim jim@luxfamily.com wrote:
On 2/8/21 12:02 AM, Poul-Henning Kamp wrote:
Lux, Jim writes:
If you happen to own something like a steel mill running electric
furnaces or an aluminum refinery, so you can manipulate the load...
More scary: Several independent studies have shown that even relatively
moderate bot-nets in the hands of somebody who knows the math of grid
stability would mean no grid stability.
This is a generalized concern with distributed generation (i.e. rooftop solar panels on houses), because a bug in the controllers for the line connected inverter could really screw things up. I suppose there's also concerns about malicious activity, but fiascos like the NEST thermostats stopping in winter of 2015/2016 are more likely.
time-nuts mailing list -- time-nuts@lists.febo.com
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