[time-nuts] 1 PPS users?

Francis Grosz fgrosz at otiengineering.com
Tue Dec 20 12:50:34 EST 2016


Folks,

One thing that is sometimes poorly understood is that on a power
system real power flow (Watts)is primarily determined by phase; voltage
determines reactive power flow (VARs).  This means power system operators
are very interested in the phase difference between the two ends
of a transmission line, for example.  GPS has made it possible to
measure this accurately even over long distances using purpose-built
instruments.  Google "Phasor Measurement Units" got more information.

       Francis Grosz


--------------------------------------------------
Message: 2
Date: Mon, 19 Dec 2016 11:46:41 -0500
From: Bob Camp <kb8tq at n1k.org>
To: Tom Van Baak <tvb at leapsecond.com>, Discussion of precise time and
        frequency measurement <time-nuts at febo.com>
Subject: Re: [time-nuts] 1PPS users?
Message-ID: <F2624A9E-FDBF-4EC4-8835-16B4A7A0CA0A at n1k.org>
Content-Type: text/plain; charset=utf-8

Hi

> On Dec 19, 2016, at 10:11 AM, Tom Van Baak <tvb at LeapSecond.com> wrote:
>
>> I believe the power industry is using GPS provided time to stamp power
>> events for analysis as well.
>
> Chris,
>
> Yes, in fact one of the first applications of hp's SmartClock was just
that:
>
> "Accurate Transmission Line Fault Location Using Synchronized Sampling"
> http://leapsecond.com/hpan/an1276-1.pdf

There is an FCS paper that pre-dates that by about a decade. The guys at
Quebec Hydro set up GPS to monitor the phase state in their main distribution
network and wrote the paper. I don’t have an FCS DVD handy to dig it up. I
also have no idea if there is a copy outside a pay wall. They went into a bit
more detail on what they saw. It gives you a bit better feel for how it works
in the real world.

Bob


>
>
> Bob,
>
> For more background on 1PPS and time synchronization see:
>
> "GPS and Precision Timing Applications"
> http://www.hpmemoryproject.org/an/pdf/an_1272.pdf
>
> "The Global Positioning System and HP SmartClock"
> http://www.hpl.hp.com/hpjournal/96dec/dec96a9.pdf
>
> Other useful hp app notes for time nuts:
> http://leapsecond.com/hpan/list.htm
>
> /tvb
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