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: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] 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 <[EMAIL PROTECTED]>, "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 [EMAIL PROTECTED] | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
