[GTALUG] NTP's Fate Hinges On 'Father Time' - InformationWeek

[Stewart C. Russell]

On 2015-03-15 10:48 AM, James Knott wrote:
> With 3 phase power, there are 6 points within the cycle where
> sync can occur, so power phase will never be more than +- 30° out of
> sync

I may have misspoken a bit about the purpose of the GPS. It's for
keeping the phasor* measurement unit (PMU) in sync. These units report
back to the system operator so that early signs of grid problems (and by
early, that would be a few seconds) can be managed remotely. PMUs were
required after the 2003 blackout: there was no shortage of diagnostic
information after that outage, but most of it had imprecise time
stamping, so was of little use to the postmortem investigation.

Here's the PMU that every wind and solar project seems to use:
https://www.selinc.com/synchrophasors/

It's not as pretty as the Synchronome clock that hangs in the board room
of the IESO in /redacted/ (one is not supposed to know where their HQ
is: it has no sign, is heavily armoured, runs on positive pressure,
etc.) which was used to manage The Hydro's grid. The SEI unit is a
little easier to interface to than the Synchronome's invar pendulum, though.

Large solar inverters synthesize their power waveform by copying the
incoming waveform. Unless they are tightly controlled, they'll happily
act as little repeaters for any sync problems.

cheers,
 Stewart

*: Steinmetz for the win!
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