60 Hz measurement party
We are more a group of experimenters than lamenters, so
here's an open invitation to all of you in the US to join me
on a 60 Hz measurement party, starting as soon as you
can and lasting as many weeks or months that it takes to
get interesting plots.
There's no agenda; we measure because we can. Anything
about precise time is fun. There hasn't been a leap second
to watch for a while so this is the next best thing.
The last time I carefully measured 60 Hz was in 2004. See:
http://www.leapsecond.com/pages/mains/
To overcome some questions about that data set, last year I
collected 60 Hz data using a GPSDO PIC that time-stamped
each zero crossing (yes, it's excessive but since when has
that stopped me). I'll restart that now and let it run all summer.
Anyway, you're welcome to use any 60 Hz monitoring method
that you can think of, whether seriously technical or just plain
humorous; clever or Rube Goldberg. Actually, the greater the
variety of methods used the more fun the group project will be.
It could be as simple as noting AC wall clock time once a day
and making a summer plot on the back of an envelope.
Or as weird as integrating the hum of a sound card on a PC
running NTP making MRTG plots. Let your imagination flow.
Please consider contributing to the effort. It seems the last
time anything interesting happened with mains frequency was
when Los Angeles changed from 50 Hz to 60 Hz in 1936.
Thanks,
/tvb
http://www.LeapSecond.com/time-nuts.htm
On 06/25/2011 09:34 PM, Tom Van Baak wrote:
We are more a group of experimenters than lamenters, so
here's an open invitation to all of you in the US to join me
on a 60 Hz measurement party, starting as soon as you
can and lasting as many weeks or months that it takes to
get interesting plots.
There's no agenda; we measure because we can. Anything
about precise time is fun. There hasn't been a leap second
to watch for a while so this is the next best thing.
The last time I carefully measured 60 Hz was in 2004. See:
http://www.leapsecond.com/pages/mains/
To overcome some questions about that data set, last year I
collected 60 Hz data using a GPSDO PIC that time-stamped
each zero crossing (yes, it's excessive but since when has
that stopped me). I'll restart that now and let it run all summer.
Anyway, you're welcome to use any 60 Hz monitoring method
that you can think of, whether seriously technical or just plain
humorous; clever or Rube Goldberg. Actually, the greater the
variety of methods used the more fun the group project will be.
It could be as simple as noting AC wall clock time once a day
and making a summer plot on the back of an envelope.
Or as weird as integrating the hum of a sound card on a PC
running NTP making MRTG plots. Let your imagination flow.
Please consider contributing to the effort. It seems the last
time anything interesting happened with mains frequency was
when Los Angeles changed from 50 Hz to 60 Hz in 1936.
Great idea Tom!
I'm safely on my 50 Hz grid over here, so I let you guys play around in
your end.
Maybe we should do something on our grid, we are a few time-nuts on the
nordic grid.
Cheers,
Magnus
Great idea Tom!
I'm safely on my 50 Hz grid over here, so I let you guys play around in
your end.
Maybe we should do something on our grid, we are a few time-nuts on the
nordic grid.
Cheers,
Magnus
Magnus,
Yes, after the current 60 Hz excitement here in the US winds down
my longer-term idea is for many of us to continuously monitor our
local power frequency with some sort of web-uploading TAPR kit
and then have an informal international TDEV competition. There
are now time-nuts in dozens of countries so this is both possible
and interesting.
You're welcome to collect data on your 50 Hz; it could serve as a
benchmark for us time drifters here in the west.
Extrapolating further, I wonder if anyone has done common view
time transfer based on synchronized power grids? Although not
as precise as LF or TV or GPS methods it would make a nice
demo of the concept.
/tvb
Hi Tom,
On 06/26/2011 01:07 AM, Tom Van Baak wrote:
Magnus,
Yes, after the current 60 Hz excitement here in the US winds down
my longer-term idea is for many of us to continuously monitor our
local power frequency with some sort of web-uploading TAPR kit
and then have an informal international TDEV competition. There
are now time-nuts in dozens of countries so this is both possible
and interesting.
You're welcome to collect data on your 50 Hz; it could serve as a
benchmark for us time drifters here in the west.
Extrapolating further, I wonder if anyone has done common view
time transfer based on synchronized power grids? Although not
as precise as LF or TV or GPS methods it would make a nice
demo of the concept.
Infact, Poul-Henning and I had the idea to test this on our grid to see
what kind of performance we would get out of it. He sent me a
transformer prepped for the work, but it seems both of us got caught up
doing other stuff to follow through, but this is a good trigger.
We should recall that IEEE 1588 was originally created to meet the power
industries need for synchronisation. There are players in the PTP world
that became big thanks to the power industry.
Anyway, a suitable measurement set-up would include a GPS, a transformer
for measurement signal, and a simple TIC of choice, such as a PICTIC.
Hook the start pulse to the PPS and the stop pulse to the power grid.
Cycle slips will be easy to see in data (20 ms or 16.67 ms steps) so
compensation and counting is quite easy to do in post-processing.
It could be interesting just to monitor the phase of the L1, L2 and L3
phases of the house. :)
Cheers,
Magnus
Extrapolating further, I wonder if anyone has done common view
time transfer based on synchronized power grids? Although not
as precise as LF or TV or GPS methods it would make a nice
demo of the concept.
/tvb
Interesting idea.. but here's a potential wrench in the works.. the
phase in the "consuming area" is always lagging the phase in the
"sending area"... as the amount of power sent varies, the phase
difference varies.
So, for instance, you're up in the Pacific NW.. generally a "sender" of
power via the Pacific Intertie down to us in the LA area.
What might be interesting is for both of us to measure phase against
some common reference (e.g. GPS) and then do a delta.
Then compare that delta (perhaps integrated over a day?) against the
published power that's been transmitted over the links (CAISO has this
on their website, I think)
There's also a fair amount of phase shift possible between transmission,
through distribution to your house. Maybe some sort of E/H field pickup
under a HV power line (if that didn't trigger the DHS dragging you away).
The field should be easily detectable. For an exercise when I was
substitute teaching a coworker's EM statics class at Cal State
Northridge, I had them work out whether a) a compass needle would
deflect under the DC link (carrying 3000A), and b)whether you could
measure the current that way. The general answer is yes and yes,
although it's a lot easier if one of the links is down and they're
running with the ocean return path.
On 06/26/2011 01:07 AM, Tom Van Baak wrote:
Extrapolating further, I wonder if anyone has done common view
time transfer based on synchronized power grids? Although not
as precise as LF or TV or GPS methods it would make a nice
demo of the concept.
/tvb
(with pretty plots. Posted to 'nuts 1.5 years ago)
The two sites were on different 60kV radials, but within the same city.
I wonder what fun things one might deduce by watching the difference in
phase across the continent?
/Kasper Pedersen
The files on the site are pretty old. I still have this in operation to
a time server where I can get the space, power, and bandwidth, but not
the antenna space.
RDS is a frequency standard?
-----Original Message-----
From: Kasper Pedersen time-nuts@kasperkp.dk
Sender: time-nuts-bounces@febo.com
Date: Sun, 26 Jun 2011 01:53:02
To: time-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] 60 Hz measurement party
On 06/26/2011 01:07 AM, Tom Van Baak wrote:
Extrapolating further, I wonder if anyone has done common view
time transfer based on synchronized power grids? Although not
as precise as LF or TV or GPS methods it would make a nice
demo of the concept.
/tvb
(with pretty plots. Posted to 'nuts 1.5 years ago)
The two sites were on different 60kV radials, but within the same city.
I wonder what fun things one might deduce by watching the difference in
phase across the continent?
/Kasper Pedersen
The files on the site are pretty old. I still have this in operation to
a time server where I can get the space, power, and bandwidth, but not
the antenna space.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
On 06/26/2011 02:18 AM, lists@lazygranch.com wrote:
RDS is a frequency standard?
RDS can give time of day, notice how it says "FM radio RDS+pilot CV" so
the 19 kHz pilot tone is used in conjunction with RDS.
The danger in that is that RDS time of day setting may be bogus, since
some broadcasters does not guarantee to steer it even if it happens to
be correct most of the times. The traceability of the pilot tone may
also be bogus. For common view it would kind of work.
Cheers,
Magnus
In message 4E066FAC.5090709@rubidium.dyndns.org, Magnus Danielson writes:
Infact, Poul-Henning and I had the idea to test this on our grid to see
what kind of performance we would get out of it. He sent me a
transformer prepped for the work, but it seems both of us got caught up
doing other stuff to follow through, but this is a good trigger.
Yeah, life, don't talk to me about life... :-)
Actually what I wanted to measure back then was the phase-stiffness
of the grid between us.
This may be relevant to Tom's experiment as well, and in particular
to those of you living in California, so let me explain what it is:
Imagine two time-nuts, N1 and N2, two generators G1 and G2 and
various chains of transformators T1a... and T2a... in the same
powergrid but some n*100km apart.
G1 --- T1a -+- T1b ------------------------T2b -+- T2a --- G2
| |
T1c T2c
| |
N1 N2
If all the power is generated by G1, the absolute GPS relative
phase seen at N1, depends on G1, T1a and T1c, which N2 sees
the combined effects og G1, T1a, T1b, T2b, T2c. When G2 produces
all the power, the picture reverses and when G1 and G2 each produce
half the phase difference btween N1 and N2 should be constant.
(But not zero, because they may not be on the same of the three
phases and because grid transformers shifts phases around to match
things up. Long story, not for today.)
Which way you push power through T1b and T2b affects what they do
to the phase of the grid on either side so the phase difference
seen between N1 and N2 depends on how power flows in the grid.
The reason everybody in the same grid sees the same frequency, is
that when you have a big heavy generator, frequency is a usable
proxy measurements for energy.
If you add an electrical load, the generator have to produce more
electricity which takes more mechanical work causing the
turbine to slow down. And vice versa.
Typically, a frequency deviation of as little as 0.02 % will cause
regulation of turbine steam.
Load changes also cause the voltage to change, but this is much
less pronounced and much harder to measure/regulate with, primarily
because of the very noisy measurements.
So the power-grid basically doesn't use voltage for regulation.
Various mechanisms keep the voltage inside a +/- 10% tolerance
at various points and that's that.
With me so far ?
All this breaks down once we start adding power-producers which
are not based on huge rotating lumps of copper-ensnarled iron.
Solar cells, wind generators, HVDC transmission, electrical cars
feeding battery power and all these other fancy modern things, feed
power into the grid with a computer controlled switch mode gadget
which just tracks whatever phase and frequency your grid has right
now.
When the frequency changes on one of these switchmodes, they just
follow the grid, they do not try to join in on the "voting" on
the frequency by trying to pull the grid ahead or behind depending
on their power-state.
As the grid moves from big rotating lumps of iron to switch mode
attachment, a larger and larger fraction of the generation capacity
free-wheels in the frequency 'voting'.
At some point, the system will no longer be stable, and something
has to happen.
My particular corner of the world is ground-zero for this, because
we generate 1/5th of our electricity with windmills and have
relatively little rotating machinery running in good winds.
So far, we are not approaching instability, at least not so that
anybody will admit it.
But the way to tell if instability is approaching, is to monitor
the phase difference between N1 and N2 as explained above, the
larger variations and the more resonance frequencies manifest
themselves therein, the more you should get involved in local
power-politics.
The future of grid regulation is to move to a "absolute frequency"
model, where the frequency is UTC-locked through-out the grid, and
regulation happens only on voltage.
There is a lot of fancy technology involved in this, and som scary
propositions about what we can and can not do with "holistic grid
regulation" and other such buzzwords.
Really long term, Edison will win and long-haul electricity will
all happen on HVDC lines. When we get buck/boost converters working
directly on HVDC, everything will be much simpler and stabler, so
people are seriously dragging their feet.
My idea for measuring this, was to measure the time from the
utc second from a GPS receiver to the first zero-crossing of
the grid, and try plot Magnus and my measurements together.
--
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 quite like your generator description of "huge rotating lumps of
copper-ensnarled iron". It brings me back to around 20 years ago, when I
was a plant electrician at an older railcar manufacturer. They had huge
open-frame synchronous motors, from around the 1930's, that ran their air
compressors, and why they used this type of motor is anybodies guess. If I
remember right, they were rated at around 200 HP, or so, and were about 8
feet in diameter. The rotor shaft was mounted on huge babbit bearings upon
concrete pillars, and about 1/3 of the motor sat in a pit in the concrete
floor. I used to have to repair the brushes on the slip rings constantly,
until I talked the boss into adding a shunt across the n.o. contacts on the
250 Vdc contactors to quench any arcing. The motors stator itself ran on
4160 Vac. Would the other compressors have to run in sync somehow, as all
of them had these motors, just some a little smaller than the others? They
drove large single cylinder compressors that fed something like a 6 inch
air line (pipe). However, they all did not run at once, and they only did
when there was a larger demand for air. Timing is the only thing I can lay
this to, and was wondering about it.
Best,
Will
*********** REPLY SEPARATOR ***********
On 6/26/2011 at 5:38 PM Poul-Henning Kamp wrote:
In message 4E066FAC.5090709@rubidium.dyndns.org, Magnus Danielson
writes:
Infact, Poul-Henning and I had the idea to test this on our grid to see
what kind of performance we would get out of it. He sent me a
transformer prepped for the work, but it seems both of us got caught up
doing other stuff to follow through, but this is a good trigger.
Yeah, life, don't talk to me about life... :-)
Actually what I wanted to measure back then was the phase-stiffness
of the grid between us.
This may be relevant to Tom's experiment as well, and in particular
to those of you living in California, so let me explain what it is:
Imagine two time-nuts, N1 and N2, two generators G1 and G2 and
various chains of transformators T1a... and T2a... in the same
powergrid but some n*100km apart.
G1 --- T1a -+- T1b ------------------------T2b -+- T2a --- G2
| |
T1c T2c
| |
N1 N2
If all the power is generated by G1, the absolute GPS relative
phase seen at N1, depends on G1, T1a and T1c, which N2 sees
the combined effects og G1, T1a, T1b, T2b, T2c. When G2 produces
all the power, the picture reverses and when G1 and G2 each produce
half the phase difference btween N1 and N2 should be constant.
(But not zero, because they may not be on the same of the three
phases and because grid transformers shifts phases around to match
things up. Long story, not for today.)
Which way you push power through T1b and T2b affects what they do
to the phase of the grid on either side so the phase difference
seen between N1 and N2 depends on how power flows in the grid.
The reason everybody in the same grid sees the same frequency, is
that when you have a big heavy generator, frequency is a usable
proxy measurements for energy.
If you add an electrical load, the generator have to produce more
electricity which takes more mechanical work causing the
turbine to slow down. And vice versa.
Typically, a frequency deviation of as little as 0.02 % will cause
regulation of turbine steam.
Load changes also cause the voltage to change, but this is much
less pronounced and much harder to measure/regulate with, primarily
because of the very noisy measurements.
So the power-grid basically doesn't use voltage for regulation.
Various mechanisms keep the voltage inside a +/- 10% tolerance
at various points and that's that.
With me so far ?
All this breaks down once we start adding power-producers which
are not based on huge rotating lumps of copper-ensnarled iron.
Solar cells, wind generators, HVDC transmission, electrical cars
feeding battery power and all these other fancy modern things, feed
power into the grid with a computer controlled switch mode gadget
which just tracks whatever phase and frequency your grid has right
now.
When the frequency changes on one of these switchmodes, they just
follow the grid, they do not try to join in on the "voting" on
the frequency by trying to pull the grid ahead or behind depending
on their power-state.
As the grid moves from big rotating lumps of iron to switch mode
attachment, a larger and larger fraction of the generation capacity
free-wheels in the frequency 'voting'.
At some point, the system will no longer be stable, and something
has to happen.
My particular corner of the world is ground-zero for this, because
we generate 1/5th of our electricity with windmills and have
relatively little rotating machinery running in good winds.
So far, we are not approaching instability, at least not so that
anybody will admit it.
But the way to tell if instability is approaching, is to monitor
the phase difference between N1 and N2 as explained above, the
larger variations and the more resonance frequencies manifest
themselves therein, the more you should get involved in local
power-politics.
The future of grid regulation is to move to a "absolute frequency"
model, where the frequency is UTC-locked through-out the grid, and
regulation happens only on voltage.
There is a lot of fancy technology involved in this, and som scary
propositions about what we can and can not do with "holistic grid
regulation" and other such buzzwords.
Really long term, Edison will win and long-haul electricity will
all happen on HVDC lines. When we get buck/boost converters working
directly on HVDC, everything will be much simpler and stabler, so
people are seriously dragging their feet.
My idea for measuring this, was to measure the time from the
utc second from a GPS receiver to the first zero-crossing of
the grid, and try plot Magnus and my measurements together.
--
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.
and follow the instructions there.
__________ Information from ESET Smart Security, version of virus
signature database 5851 (20110206) __________