[BC] 110 V DC

[Jim Tonne]

Not only are the various parts of the grid on the same
frequency, they are PHASE-locked!
- JimT



----- Original Message ----- 
From: "PeterH5322" <peterh5322 at rattlebrain.com>
To: "Broadcasters' Mailing List" <broadcast at radiolists.net>
Sent: Monday, December 04, 2006 11:27 AM
Subject: Re: [BC] 110 V DC


>
>>During a cold snap in 1977 clocks gained about 30 seconds over a week in
>>New England; to maintain voltage they had to run the generators (and
>>thereby the grid) overspeed for a long enough stretch that they were were
>>unable to correct the error. Instead they just announced it in the press a
>>couple weeks later. I was surprised by this as I'd grown up in BPA-land
>>(the largest unit of synchronized power on the planet) where one thing we
>>could always count on was 60 hz.
>
> Could work for small, unconnected systems, but not for large,
> interconnected systems.
>
> The "equal area" stability criteria would be violated long before there
> was any perceptible variation in time, and the stability of a
> interconnected system takes precedence over time maintenance.
>
> The Western System, which my group at LA Department of Water & Power
> designed, is interconnected from Canada to Mexico and from the Rocky
> Mountains to the Pacific ocean, Including BPL.
>
> It takes but a small unit, specifically one of Hoover's, to maintain
> system frequency. We had a "sensitive" reed-type frequency meter in our
> Load Dispatcher's office, and it always read 60.0000... Hz, except when
> there was a system-wide disturbance, such as the Sylmar Earthquake, which
> caused the immediate separation of LADWP from BPL, and the consequent
> loss of 1,400 MW of generation capacity.
>
> BPL is interconnected to LADWP through a 1,0000 kV dc line, so the
> frequencies between the these two independent agencies is determined
> largely by the ac intertie, which interconnects BPL with "investor owned"
> utilities, which are also partners in the Western System.
>
> As long as systems remain interconnected, and the "equal area" stability
> criteria is maintained, the time will read the same, everywhere.
>
> There was never an attempt to "make up time" by overspeeding any units.
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