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Re: East Coast outage?
From: Scott A Crosby <scrosby () cs rice edu>
Date: 15 Aug 2003 21:09:09 -0500


On Sat, 16 Aug 2003 00:25:14 +0200, Iljitsch van Beijnum <iljitsch () muada com> writes:

On vrijdag, aug 15, 2003, at 23:58 Europe/Amsterdam, alex () yuriev com
wrote:


Amount of energy generated must be balanced with the amount of
energy used

at any time. Otherwise Bad Things (tm) will happen. The shutown of
the grid is a very good thing compared to what it would have been
had it not

shutdown.

It seems to me that the power guys are still living somewhere in the
last century. Is it really impossible to absorb power spikes?

I don't know, but at least reading this IEEE Spectrum article:
http://www.ece.umr.edu/courses/f02/ee207/spectrum/Grid/ implies that
long distance transmission is full of strange and nonlinear effects
such as 'reactive power', voltage support, and other technical
concepts that made me conclude that there are nasty details that are
not widely known. Excerpts follow:

   Generators at another smallpower plant also tripped. The tripping
   was due to high reactive power output associated with supporting
   transmission voltage

** Reactive power sidebar:

   Reactive power consumption tends to depress transmission voltage,
   while its production or injection tends to support
   voltage. Transmission lines both consume it (because of their
   series inductance) and produce it (from their shunt capacitance).

   Because transmission line voltage is held relatively constant, the
   production of reactive power is nearly constant. Its consumption,
   however, is low at light load and high at heavy load.

   The variable net reactive-power requirements of a transmission line
   give rise to a voltage control problem. Generators and
   reactive-power compensation equipment must absorb reactive power
   during light load, and produce it during heavy load.

   In a general emergency, when there are outages and high loading on
   re-maining transmission lines, those lines consume reactive power
   that must be supplied by nearby generators and shunt capacitor
   banks. (Reactive power can be transmitted only over relatively
   short distances.)

   If reactive power cannot be supplied promptly enough in an area of
   decaying voltage, voltage may in effect collapse. Insufficient
   voltage support may in addition contribute to synchronous
   instability. --C.W.T.

** Done

Later it talks about how ''fast capacitor-bank switching in southern
Idaho would have contained the initial 2 July outages.''. It also says
something about: ''That August day, though, the power system
stabilizers at a large nuclear plant in Southern California were out
of service. (Power system stabilization at this location is especially
effective because it is near one end of the north-south intertie
oscillation mode.)''

I think to really understand the material above one needs to read
author's book: _Power System Voltage Stability_

I also think that its hard to appreciate the stability differences
between shipping power a few hundred feet and shipping power 1000
miles. It looks like that long-distance shipping is the root cause of
the half-dozen major outages over the past 30 years. Why is the
northwest getting power 800 miles away in Wyoming instead of putting
up their own plant?


Also, 'alternative generation' isn't there yet. For instance, from
California's wind energy site
http://www.energy.ca.gov/wind/overview.html The total output of all
13000 turbines in CA, *together* average only 400MW of unreliable
power over the course of a year. Diablo Canyon (nuclear, california)
produces five times this so does Jim Bridger (coal, wyoming). After 20
years of effort and subsidies, thats 1% of CA's energy use, and 10% of
what was imported today. http://currentenergy.lbl.gov/ca/

Scott


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