> I hope some will accept the technical challenge of gathering data --
which is fairly minimal.
Andy,
It may have been before you joined time-nuts, but some years ago we
compared mains phase/frequency between Albuquerque, NM and Seattle, WA,
which in spite of being some 1500 miles apart are on the same grid.
Another test was between two nearby locations, Bellevue, WA and Redmond,
WA. All data was taken by timing zero-crossings to the microsecond with
a picPET. You'll find the results fascinating:
http://leapsecond.com/pages/mains-cv/
I'm happy to repeat any of this analysis using recent data from Hal
(CA), and you (Bellingham, WA), and me (Bellevue, WA).
A third test which is interesting is comparing independent mains
phase/frequency between different rooms of the same house. In general
you want to understand local house effects, then neighborhood effects,
then city / country effects before you jump into interstate grid
effects. It's similar to establishing baselines and noise floors when
you make precision clock measurements.
/tvb
On 7/7/2019 11:49 PM, Andy Backus wrote:
To clarify:
My research proposal is for data to be taken within the same interconnection.
It does not care about frequency.
It does not care about Time Error.
It only seeks to characterize the phase differences between the power line
signal presented in regions of the distribution system separated by significant
geographical distances.
180-degree phase reversals and three-phase transformations along the chain of
information are easily distinguishable.
Thanks for your interest. I hope some will accept the technical challenge of
gathering data -- which is fairly minimal.
Andy Backus
Bellingham, WA
(Western Interconnection)
________________________________
From: time-nuts<[email protected]> on behalf of Dave
ZL3FJ<[email protected]>
Sent: Sunday, July 7, 2019 9:23 PM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] A Research Proposal
I have here a pair of instruments that were part of a system used at one time
in a power station here in NZ to control the time error in one part of the
national grid. It controlled the selected generators and provided a real time
display of the time error between a reference standard and the 50 Hz mains
frequency. The system comprised an HP 5280A reversible counter with two
inputs, one from the mains 50 Hz as generated and one from the reference
standard. These two inputs were arranged to add counts from one input and
subtract counts from the other, such that the counter displayed zero while the
generated 50 Hz was accurate. Offsets from 50Hz were displayed as positive or
negative counts. The reference input was derived from an HP 105A quartz
oscillator and the system included provision to manually synch that to the
national standard time standard on an as required basis. The output of the
5280A counter drove an HP 6933B D/A converter, the bi-polar DC output of which
was used (both magnitude and sign) to control the governors on some of the
hydro generators. Dual HP 5321B clocks were used to display TOD from both
sources.
The 6933B is complete but the 5280A counter has been partly disassembled.
The 5321Bs never got this far-neither did the 105A- who knows, it might still
be being used as a reference!
DaveB, NZ
-----Original Message-----
From: time-nuts [mailto:[email protected]] On Behalf Of Bill
Hawkins
Sent: Monday, July 08, 2019 06:48
To: Bob via time-nuts
Subject: Re: [time-nuts] A Research Proposal
Group,
We've discussed this before, but maybe it needs to be said again.
Line frequency is not constant. There is no master PLL. Approximate
frequency is maintained by a central power dispatching office in each of the
four (?) regions tied together by their power distribution grid. The
dispatcher's goal is to create the same number of cycles of AC each day. IIRC,
power is bought and sold by the number of cycles generated. As the daytime
load increases, the generators slow down a bit. Note that it is not possible
for each generating station to control its frequency, as that would not be
stable. Instead, the dispatcher asks various plant operators to generate more
or less steam (or water flow) in order to increase the frequency. When the
load drops at night, the generators speed up a bit, and steam has to be
reduced. At the end of the day, so to speak, the number of cycles generated is
very nearly equal to the number generated if the line frequency had been steady
at 60 (or 50) cycles per second. Synchronous clocks stay accurate although
they may be off by a few seconds as dispatchers scramble to get enough steam to
keep up.
So yes, you can get phase data within a region but you must compensate timing
data as the frequency varies.
The regions are connected to each other for purposes of power sharing with DC
transmission lines. These use inverters to convert between AC and DC. The AC
frequency is controlled by the grid that it is tied to. Phase angle can be
changed to change the amount and direction of the power transferred.
So no, you can't compare data from different regions, unless you want to know
which way DC power is flowing.
I hope this was informative.
Bill Hawkins
On Thu, Jul 4, 2019, at 2:00 PM, Andy Backus wrote:
Historically, and even today, the steady frequency of AC power has
been used for timekeeping. So there may be interest here in the
following research proposal:
Within a given power distribution grid, several observers as widely
separated geographically as possible, time stamp the first two zero
crossings of the power line after each UTC second – over the course of
24 hours (86,400 pairs of data).
Popularly conceived, all the components of a power distribution grid
are phase locked – though, of course, power is taken in and out by
varying degrees of lead or lag. Frequency is maintained by a constant
balancing act between load and generation.
Typical power distribution grids, however, are sized on a scale of
thousands of miles. “Locking phase,” then, is problematic simply on
the basis of the limits of information transmission rate. Even at c,
every 1000 miles takes 5 ms, which represents a third to a quarter of
the period of the AC power waveform.
Many interesting phenomena might result from that reality, which
suggests a certain constrained flexibility over large distances –
almost as if the system is like a large lake of viscous liquid. When
there are local disturbances such as rapid load changes or sudden
generation adjustments, for example, it is quite possible harmonic
ripples could be propagated through the system.
Such effects could be observed by comparing phase data across
significant distances within a distribution grid.
Andy Backus
Bellingham, WA
USA
________________________________
From: time-nuts<[email protected]> on behalf of Thomas
D. Erb<[email protected]>
Sent: Thursday, July 4, 2019 5:23 AM
To:[email protected]
Subject: Re: [time-nuts] 60 Hz frequency and phase measurement
snip
I had a recent tour of a power station - the operators had no idea the
output was synchronized to a time standard - they just synchronize
with the local grid.
Thomas D. Erb
p: 508-359-4396
f: 508-359-4482
a: 97 West Street, Medfield, MA 02052 USA
e:[email protected]
w:www.electrictime.com<http://www.electrictime.com<http://www.electrictime.com<http://www.electrictime.com>>
Tower & Street Clocks Since 1928
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