preilley_454@comcast.net said:

How big were the grids back then?

What was the typical range of error over a day or month?

Does that operator control a single generator or a whole grid?

Does having a human in the loop help the control loop stability?

--
These are my opinions.  I hate spam.

Hi

Back in high school, one of the radio club members figured out that the “clock adjustment” took place
locally between 4:30 and 5:00 PM. Needless to say, pretty much everybody spent the next week listening
to WWV and watching the clock’s second hand go out of sync with the beeps. This was back in the  late 1960’s
and the idea of a grid was a bit looser than it is today. Indeed it was post 1964 so there were grids big
enough to take out the whole north east section of the US. Since we were very much in that area the
topic of grid sync came up. Nobody ever really had a good answer to that question. That included the
guys who ran the local power company.

Bob

In college we had a Vax 11/730 that would freak out and reboot the same time every day. Turns out the culprit was the sync pulses put on the AC for synchronizing the classroom clocks...But it took DEC a few weeks to find the culprit.

A fun way to monitor the state of the grid is to watch the web site of
the Power
Information Technology Laboratory http://powerit.utk.edu at the University
of Tennessee http://www.utk.edu, Their site lists in both tabular and
graphical (map) form the frequency of the grid. Most of it is USA-based but
there are a few other countries also monitored.

I have one of the monitors (in the table display page <
http://fnetpublic.utk.edu/tabledisplay.html> my monitor is #853 in the
Western Interconnection—I'm in California).

The monitors, about the size of a thick hardback book, plug into a
convenient AC line outlet, connect to your Internet router, and have a
small puck-style GPS antenna so that it knows the time and where it is. The
unit has an LCD display of date, time, line voltage, and line frequency.
The voltage is shown to 3 decimal digits of resolution and the frequency to
four digits.

I got my monitor from the U of T after I sent them a report on my home-made
monitor's results. It's interesting to watch the frequency wander up and
down but always average very close to 60.000 Hz. They saw I had an interest
and offered me one of their toys. The only thing it doesn't do is connect
to my PC so I can monitor it long-term. I suppose if I were clever with
network stuff there'd be a way to tap into its data stream.

Jeremy, N6WFO

On Wed, Apr 5, 2017 at 2:12 PM, Bob kb8tq kb8tq@n1k.org wrote:

Hi

Well ok, the rest of the story ….

The process of watching the line voltage slip lead me to buy my first “frequency counter”.
It was a 1950’s vintage tube based Beckman “EPUT Meter”. I doubt it cost me over $40 at
the time. It was well used but still functional  It clocked away on a  massive  MHz time base
(that’s singular not plural) and turned out to be plenty good enough to show jitter
on a 60 Hz sine wave. That got me into questions about why and stability and …. here I am
decades later.

Bob

Perhaps I should have clarified that while the synchronous machines all
run at the same frequency, that frequency depends on the balance of
steam (or hydraulic) power to the turbines that spin the generators and
the aggregate power demand. When the power is not balanced, the
frequency of the coupled system will change, but very slowly in
proportion to the size of the network of generators.

I don't know the effects of the DC tieline inverter, which can run at
any set frequency, but any difference in frequency has to affect the
power out of or into the tie line.

As to doing the clock adjustment around quitting time at 5 PM, my
experience is different. A system that took a frequency input and showed
it as a function of time revealed that the frequency sagged during the
workday and the air conditioning day, but was increased to make up the
lost cycles during the minimum load time around 4:30 AM.

In 1955 or so, The Air Force determined that the time of minimum human
activity (and hence the maximum probability of attack) was at 4:30 in
the morning. Independent research with traffic counters revealed a sharp
dip in traffic at that time of day. Adjusting the cycle count at the
time of minimum activity also minimized the cost of making that
adjustment. Sorry, I have no recent data, but it sure feels lonely to be
up at 4:30 AM.

Bill Hawkins

-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf Of Jeremy
Nichols
Sent: Wednesday, April 05, 2017 6:57 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Line Frequeny Stablity

A fun way to monitor the state of the grid is to watch the web site of
the Power Information Technology Laboratory http://powerit.utk.edu at
the University of Tennessee http://www.utk.edu, Their site lists in
both tabular and graphical (map) form the frequency of the grid. Most of
it is USA-based but there are a few other countries also monitored.

I have one of the monitors (in the table display page <
http://fnetpublic.utk.edu/tabledisplay.html> my monitor is #853 in the
Western Interconnection-I'm in California).

The monitors, about the size of a thick hardback book, plug into a
convenient AC line outlet, connect to your Internet router, and have a
small puck-style GPS antenna so that it knows the time and where it is.
The unit has an LCD display of date, time, line voltage, and line
frequency.
The voltage is shown to 3 decimal digits of resolution and the frequency
to four digits.

I got my monitor from the U of T after I sent them a report on my
home-made monitor's results. It's interesting to watch the frequency
wander up and down but always average very close to 60.000 Hz. They saw
I had an interest and offered me one of their toys. The only thing it
doesn't do is connect to my PC so I can monitor it long-term. I suppose
if I were clever with network stuff there'd be a way to tap into its
data stream.

Jeremy, N6WFO

On Wed, Apr 5, 2017 at 2:12 PM, Bob kb8tq kb8tq@n1k.org wrote:

beeps.

wrote:

"clock"

forward.

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