POWER February 2011 - 28

ASSET MANAGEMENT
units that don't trip " are susceptible to damage
from turbine blade vibration. "
There is now evidence that the 1989 storm
had impacts far beyond North America. A
June 2010 NERC study of power system risks
(www.nerc.com/files/HILF.pdf) noted, " Large
geomagnetic storms can have a global reach
and produce impacts to other developed power
grids around the world. For example in England,
the March 1989 storm is suspected to
have caused damage to two 400kV transformers.
The operators of the power grid in England
also understand that, since 1989, their
power grid has become significantly more
dependent on transmission system static var
and switched capacitance devices for system
voltage regulation, thus making their system
more vulnerable to future geomagnetic storms.
Even recent and much lower intensity storms,
such as those in late October 2003, provide
evidence of increasing vulnerability. " A minor
2003 storm even reached the Southern Hemisphere,
according to NERC, producing " lower
intensity, but long duration GIC disturbances
in South Africa " that " caused permanent damages
and loss of 15 EHV transformers in the
[South African] Eskom system. "
Remarkably, the 1989 solar storm was not
particularly ferocious. As Luke Van der Zel
of the Electric Power Research Institute told
POWER, " In historical context, 1989 was
minor. There is evidence that larger storms
have been seen. " In 1859, the largest known
storm, called the " Carrington Event, " struck
Earth. A 2009 National Academy of Sciences
workshop on space weather described
this 1859 storm as " by several measures the
most severe space weather event on record.
It produced several days of spectacular auroral
displays, even at unusually low latitudes,
and significantly disrupted telegraph services
around the world. It is named after the British
astronomer Richard Carrington, who observed
the intense white-light flare associated
with the subsequent geomagnetic storm. "
More to the modern point, another gigantic
storm struck the planet in May 1921, causing
substantial destruction. Government experts
have defined the 1921 storm as a 1-in-100year
event, which doesn't mean it can't happen
more frequently than that but simply gives
an indication of its severity. In addition to the
1989 storm that took down Hydro-Québec,
a minor solar storm in October-November
2003 took down the U.S. Federal Aviation
Administration's new GPS-based navigation
system for 30 hours and damaged electrical
systems from Scandinavia to South Africa.
Modern storms have caused and potentially
can cause much more damage and
disruption than earlier events, because electrical
and electronic infrastructures around
the world are more ubiquitous, complex, and
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POWER | February 2011
connected. NASA scientist Tony Phillips
notes that " power grids may be more vulnerable
than ever. The problem is interconnectedness.
In recent years, utilities have joined
grids together to allow long-distance transmission
of low-cost power to areas of sudden
demand. " Interconnectedness, Phillips
observes, " makes the system susceptible to
wide ranging 'cascading failures.' "
Solar storm expert John Kappenman adds
that larger, longer, and bigger transmission
systems add to the vulnerability to GICs, by reducing
the resistance of the grid. " The miles of
high-voltage transmission voltage in the U.S.
have increased by a factor of 10 over the last 50
years, " Kappenman said in an interview. " We
now have a much larger antenna in place. "
To address the modern impacts of solar
storms, NASA commissioned a National
Academy of Sciences 2008 report, " Severe
Space Weather Events-Understanding Societal
and Economic Impacts " (at www.nap.edu
search for report 12507). A team led by Kappenman
modeled the potential effects of the
May 1921 storm on the modern U.S. system.
That study, which is the basis of all further
analysis to date, found that the risks involved
loss of more than 350 high-voltage transformers
and power outages to more than 130,000
million Americans. The loss of electricity
would spread across the physical infrastructure
and would include " water distribution affected
within several hours; perishable foods
and medications lost in 12-24 hours; loss of
heating/air conditioning, sewage disposal,
phone service, fuel re-supply and so on. "
Globally Unprepared
Is the world ready for these sorts of events?
Specifically, is the U.S. electrical system, the
most highly developed in the world, equipped
to prevent or cope with a disastrous solar
storm? The question goes to both the engineering
of the physical power system and the
intellectual and regulatory environment that
surrounds the physical system. The answer
is far from obvious. Although the threat of
geomagnetic storms is well understood in the
electric industry, and much effort is being devoted
to understanding and preparing for this
troubling contingency, whether those efforts
will prove protective or able to address the
adverse consequences is unclear (Figure 5).
The Electric Power Research Institute
(EPRI) has been devoting considerable effort
to studying geomagnetic storms since
the 1989 event. EPRI has produced voluminous
work on the impacts of solar storms
on electric systems, working through its
SUNBURST project, which aims to " monitor,
study, and mitigate " geomagnetically induced
currents on the power grid. A late 2008
update on SUNBURST from EPRI warns,
" With the solar cycle just passing the minimum
and solar storm activity at a 50-year
record low, it is easy to temporarily forget
4. Electrical connection. According to NASA, " Solar storms, which occur frequently, can
disrupt communication and navigational equipment, damage satellites, and even cause blackouts. "
In this artist's view of a solar storm, the purple line indicates the bow shock, the outer
edge of the magnetosphere; the blue lines surrounding Earth represent its protective magnetosphere.
" The magnetic cloud of plasma can extend to 30 million miles wide by the time
it reaches Earth. The magnetic field orientation of the coronal mass ejection (CME) is a major
factor as to whether the Earth will suffer many consequences from any given CME. After a CME
blasts from the Sun towards Earth, a cloud of charged particles impacts our magnetosphere in 2
to 4 days. Thus, the Earth is electrically connected to the Sun, " explains NASA. Source: NASA

http://www.nerc.com/files/HILF.pdf http://www.nap.edu http://www.powermag.com

POWER February 2011

Table of Contents for the Digital Edition of POWER February 2011