POWER February 2011 - 26

ASSET MANAGEMENT
1. Stormy weather coming. The cyclical nature of the number of sunspots is predictive
of the severity and number of expected solar storms-more sunspots mean more solar storms
of increasing intensity. Data collected through November 2010 are shown, with predicted values
in red. According to the Solar Cycle 24 Prediction Panel, the minimum of the current 11-year
cycle occurred in December 2008. Source: NOAA
Smoothed monthly values
175
150
125
100
75
50
25
000 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19
Januarys
Biesecker noted an increase in sunspot activity
in early 2008, which he described " as like
the first robin of spring. In this case, it's an
early omen of solar storms that will gradually
increase over the next few years. "
The fear shared by scientists at the National
Aeronautics and Space Administration
(NASA) and NOAA is that our planet could
be entering a particularly vicious " solar maximum. "
The sidebar describes the various satellites
that are keeping an eye on the sun.
Storm Crashes Canadian Grid
What happens when a solar storm strikes
somewhere on our planet? In early 1989, a
solar storm-not a particularly severe event
by historical records-erupted, creating a
gust in the solar wind that reached northern
Canada in a matter of days. The arrival of
the solar particles caused severe disturbances
in the planet's magnetic field. That was
the beginning.
Here's how a NASA web site (www.nasa
.gov/topics/earth/features/sun_darkness.
html) describes what happened: " On Friday
March 10, 1989 astronomers witnessed a
powerful explosion on the sun. Within minutes,
tangled magnetic forces on the sun had
released a billion-ton cloud of gas. It was like
the energy of thousands of nuclear bombs
exploding at the same time. The storm cloud
rushed out from the sun, straight towards
Earth, at a million miles an hour. The solar
flare that accompanied the outburst immediately
caused short-wave radio interference,
including the jamming of radio signals from
Radio Free Europe into Russia. It was thought
26
that the signals had been jammed by the
Kremlin, but it was only the sun acting up! "
On March 13, 1989, notes a NERC report,
seven static VAR compensators on HydroQuébec's
(HQ) giant La Grande high-voltage
transmission network shut down in a matter of
seconds. Induced direct current from the solar
storm caused the transmission system voltage
to drop, frequency to rise, and the line to trip
off. The rest of the HQ transmission system
collapsed in seconds. It took nine hours to restore
18,000 MW of power to the network.
The solar storm left considerable wreckage in
its path, including two La Grande 4 generating
station step-up transformers, thyristor and capacitor
banks at several units, and static VAR
compensators across the system that were
damaged or destroyed.
The damage was not confined to the Canadian
system. Perhaps the most chilling effect
of the storm was a thousand miles away
in New Jersey, where the 1,160-MW Salem
1 nuclear power plant sits on an artificial
island at the mouth of the Delaware River,
along with two other nuclear units. The solar
storm induced current on the PJM 500-kV
transmission system, which damaged the Salem
Unit 1 step-up transformer, resulting in
" large melted masses of copper and copper
shot. " The transformer's winding insulation
confined the damage, and the plant did not
trip off during the solar attack. Engineers discovered
the damage after the storm, but the
transformer had to be replaced, at a cost of
millions of dollars.
The effects on the North American electrical
grid were profound. According to NASA
www.powermag.com
Monthly values
Predicted values (smoothed)
astronomer Sten Odenwald, " The Quebec
blackout was by no means a local event. Some
of the U.S. electrical utilities had their own
cliffhanger problems to deal with. New York
Power Authority lost 150 megawatts the moment
the Quebec power grid went down. The
New England Power Pool lost 1,410 megawatts
at about the same time. Service to 96
electrical utilities in New England was interrupted
while other reserves of electrical power
were brought online. Luckily, the U.S. had the
power to spare at the time . . . but just barely.
Across the United States from coast to coast,
over 200 power grid problems erupted within
minutes of the start of the March 13 storm.
Fortunately none of these caused a blackout.
" In space, some satellites actually tumbled
out of control for several hours. NASA's TDRS1
communication satellite recorded over 250
anomalies as high-energy particles invaded the
satellite's sensitive electronics. Even the Space
Shuttle Discovery was having its own mysterious
problems. A sensor on one of the tanks
supplying hydrogen to a fuel cell was showing
unusually high pressure readings on March 13.
The problem went away just as mysteriously after
the solar storm subsided. "
Solar Tsunami Coming
A 1990 North American Electric Reliability
Council (now the North American Electric
Reliability Corp., NERC) report analyzing
the 1989 solar storm defined the physics of
a solar disturbance (Figure 4). " As the solar
particles arrive at the earth, " said the report,
" they cause rapid fluctuations of the earth's
geomagnetic field. This, in turn, produces an
induced earth-surface potential and geomagnetically
induced currents, or GIC. GIC appears
as a quasi-dc current (an ac waveform
with a period of several minutes), and for all
intents and purposes, appears as dc to the
bulk electric system. The consequences of
this dc current are to drive transformer cores
into saturation. This, in turn, causes significant
heating from stray flux, increases var
losses that depress system voltages, and can
damage the transformer itself. "
In the flat language of engineering, the
NERC analysis adds that the induced currents
" can precipitate a multiple-contingency
incident, which, under certain operating conditions,
can jeopardize the integrity of the
bulk electric systems in North America. Specifically,
harmonic currents can cause overcurrent
relays to trip capacitor banks because
capacitors offer a lower impedance path for
harmonics. Similarly, static var compensators
can trip for over-current or over-voltage
protection. " The complex events resulting
from the induced currents can take generators
down along with the grid, as generators
" are not immune to harmonic current. " Even
POWER | February 2011
Sunspot number

http://www.nasa http://www.powermag.com

POWER February 2011

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