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Re: power failure causes and effects
From: Charles Sprickman <spork () inch com>
Date: Fri, 15 Aug 2003 02:36:50 -0400 (EDT)


On Fri, 15 Aug 2003, Mehmet Akcin wrote:

I have been hearing on the TV that some places that had power failure have
started getting their power back, reporters say hopefully by the morning all
of the places where had power failure will back online.

In NYC it seems like either some places are running out of battery or
diesel.  For example I see L3 at 111 8th up fine as well as Focal at 32
Old Slip.  However one of my upstreams at L3, Hurricane Electric, dropped
off for a while.  After about 10 minutes they were alive again but rather
than the normal path out via He->MFN, they were using a L3 connection.  So
whatever was tying some of their sites together went dark.

Additionnaly, I just got a flood of outage notifications from Covad all
RFO "power outage".  So either VZ is not running gensets or they shed
CLECs first (nahh....).

On another note, half of my NY Metro DirecTV stations are gone.  I have no
idea what the path is from studio -> DTV, but I assume they don't pull it
off the air.

Charles

Mehmet Akcin

----- Original Message -----
From: "Marshall Eubanks" <tme () multicasttech com>
To: "Fred Heutte" <aoxomoxoa () sunlightdata com>; <nanog () merit edu>
Sent: Friday, August 15, 2003 12:51 AM
Subject: Re: power failure causes and effects



On Thu, 14 Aug 2003 19:12:04 -0700
 Fred Heutte <aoxomoxoa () sunlightdata com> wrote:

It looks like DC may have had a close call - the University of Maryland
was
dark for about 1 hour, and I have heard several news reports here stating
that the local (DC regional) power grid just managed to
decouple from wider East Coast grid in time to avoid a collapse here.

Regards
Marshall Eubanks


Most of the early rumors about causes of the power failure
have proven incorrect -- fire at a New York City power plant,
etc.

Most likely is a congestion failure in the Niagara-Mohawk
grid, which covers a large part of New York state and has
feeders across into Canada.

Congestion failures happen when power flows through a
particular switching station are high, and a component
fails either directly or because of a power surge caused by
a failure elsewhere.

The imbalance caused by an open or short circuit will then
immediately spread through the rest of the grid unless action
is taken to disconnect, or point failures occur (resulting in fires
and explosions from degradation of power transmission
equipment, transformers, etc., not a pretty outcome at all) --
or both.  In general, transmission grids are designed from a
failsafe perspective, meaning that it is much safer to cause
rolling brownouts or blackouts than to let key components
such as transmission substations or power plants have a
catastrophic failure.

Since the entire grid has to be in sync and supply and demand
must be in relative parity at all times, the usual strategy in
these cases is to isolate the affected area, "island it" by
shutting down power ingress and egress (tripping safety
breakers at major crossing points), and shutting down
power plants in the vicinity that will have stress failures
if they don't have sufficient load to balance their output.

The problem is that power travels faster than even the
highest-speed switching equipment can operate, so the
surges causing a cascading failure like this afternoon's can
spread very quickly, like ripples in a pond.

The weather was hot and humid but completely within
range for the time of year, so this has to be counted as a
"normal accident."  It's likely that whatever component
initially failed and triggered the shutdown was within
its usual tolerances and simply had an ordinary breakdown.
Of course, to spread, a massive outage like this also exposes
other weaknesses and hidden dependencies in the system,
which might be other physical components, software,
operator error, etc.

The system is remarkably resilient in most circumstances,
which is what five-nines or more is all about.  But rust never
sleeps, and underinvestment in key transmission corridors in
New England, New York north of Manhattan and in
parts of the Midwest is no doubt an underlying cause.

As to the root cause of that engineering problem -- the
answer is politics, some of it congressional, and I will say no
more in this forum.

Fred Heutte

Portland, Oregon
energy policy analyst and net geek





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