[time-nuts] Features of a Precision Clock?

Bill Hawkins bill at iaxs.net
Sun Oct 8 12:28:56 EDT 2006


Well, 10% is extreme, but in the NE USA it is possible to
do that by losing one tie line. During the NE blackout on
Nov 9, 1965, less than 10% fell off the line. The remaining
generators slowed down and tripped under-frequency relays
at about 57 Hz or tripped overload breakers. This split the
network into islands in about 4 seconds. The resulting
instability took out most of the remaining generators inside
5 minutes. See http://www.cmpco.com/about/system/blackout.html

Please do not discredit all of my explanations by saying they
are old. The control engineer that I talked to in 2002 worked
in a 2,400 megawatt coal-fired plant built in the 70's. Many
of the US plants are that old.

Also, Newton's F=MA and Ohm's law are much older, but still
quite valid (for large numbers of atoms). Similarly, the laws
of control and stability still apply to mechanical systems.
The governor for a hydroelectric turbine operates the same as
the governor for a steam turbine. There can only be one
integrating controller for a coupled network to be stable.

The fuel incremental cost for atomic energy is a lot cheaper
than the cost of coal, oil or gas. Power dispatchers also
hold down costs by assigning extra load to stations in order
of fuel cost.

Producers bill for megawatt-hours delivered to the grid. This
introduces the element of time. It is tempting to use extremely
accurate time, but the measurement of watts is not much better
than 0.1%. The bean counters will tell you that 0.1% of a US
billion dollars is a million dollars. They would like to be
accurate to the penny. Is this the "cheating at the scale"
problem that you mentioned?

Regards,
Bill Hawkins

Never attribute to malice what can adequately be explained by
the limitations of a three pound brain. Ah, unless the person
is known to be a psychopath with a damaged brain.


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Poul-Henning Kamp
Sent: Sunday, October 08, 2006 1:28 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Features of a Precision Clock?

In message <000001c6ea65$40156be0$0900a8c0 at cyrus>, "Bill Hawkins"
writes:

>Think of the incredible amount of energy stored in many rotating 
>generators linked by the synchronous network.

This is actually far less than you seem to think.

>If the load suddenly increased 10% [...]

Then all generators would trip and disconnect from the grid.  No
reasonably sized turbine driven generator survives a 10% load jump
without exensive repairs.

Your explanation was true about 30 years ago, not so any more.

After deregulation, electrical grids run very close to the edge because
nobody makes money on the reserve capacity and therefore everybody only
produces exactly what they are legally required to.

The main reason for all the research into UTC locked grids is that it
would prevent produces from "cheating at the scale".

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by
incompetence.

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