POWER November 2014 - 72

COMMENTARY
New Grid Vulnerabilities
Demand New Technology
Dr. Jason Black
Q
uick, the grid is down-what do you do?
If your procedures are like most, you rely on a combination
of static restoration plans, emergency management
system protocols, and operator experience and
intuition. But today's grid is increasingly complex and is
subject to new vulnerabilities.
Physical security is a critical concern, especially in the wake
of recent high-profile attacks against America's electrical transmission
infrastructure. These incidents paved the way for new
physical security requirement recommendations from the North
American Electric Reliability Corp., which should be adopted
industry-wide to avoid disruptive events. But fully protecting
the grid requires us to look at internal threats as well as external
ones, and to put systems in place to reduce vulnerabilities at the
operator level for utilities and power generation.
We must recognize that no system is 100% blackout proof.
America's aging infrastructure and our changing mix of energy
creates significant system vulnerabilities that make bringing the
grid back online more challenging and potentially more costly
for utilities as well as their customers.
In the event of a blackout, grid operators rely on a limited
number of " black-start units " - generators with a self-start capability,
to jumpstart the grid. Once the black-start units are
operational, grid operators then generate " cranking paths " from
these generators to non-black-start units, which require external
power sources to start up, to bring the rest of the grid online.
These cranking paths are typically generated using static plans
based on a set of assumptions about equipment availability, infrastructure
integrity, and other variables that may or may not
be valid for the specific emergency at hand. Experienced grid
operators must make adjustments to these cranking paths based
on their knowledge of the specific circumstances and their experience
in handling outages and power overloads.
However, ongoing changes over the last decade have altered
many of the assumptions underlying operator intuition and can
make the grid more complex to bring back up after a blackout.
Alternative Fuels Add Uncertainty
The switch from coal-fired power plants to gas generation has
introduced new vulnerabilities to the system as a whole. While
natural gas brings many benefits, gas plants rely on pipelines
to bring in fuel as it is burned. Unlike traditional coal plants,
gas facilities typically do not have large volumes of fuel stored
on site. A large-scale disaster that interrupts the power grid
may also interrupt the gas supply to these power plants, leaving
fewer resources for power plant operators to rely on to create
cranking paths back to restoration.
Greater focus on renewable energy sources also introduces uncertainty,
as it is difficult to predict how much power they can
generate (if any) after a disaster strikes, making them unsuitable
for restoration.
Many black-start plans utilized old, reliable coal plants
72
that are now being retired. Combined, this means that grid
operators have fewer options to rely on to restore the grid
during a blackout.
Grid Complexity Creates Unpredictability
The increased complexity of the grid as a whole also makes it
more difficult to adjust recommendations and generate new
cranking paths on the fly. The increasing sophistication and
automation of power distribution systems and the smart grid
increase this unpredictability. Higher degrees of connectivity,
reliance on more distant power sources, and a system that combines
aging infrastructure with a hodgepodge of new technologies
make it harder to predict the effects of decisions that a grid
operator makes.
Technology Holds the Key
One way to speed a recovery effort is to take advantage of new
technologies that enable real-time command and control over
the grid. A good example can be found in the use of the Agora
system by utilities in Spain and California. Agora is a system
developed by Gridquant that takes advantage of a patented, deterministic
load-flow solver that allows operators to visualize
grid conditions in real time, even up to the point of voltage
collapse. In the event of a blackout, it operates much like a GPS,
providing dynamic, step-by-step guided solutions that are continuously
recalculated in response to changing grid conditions
and equipment availability.
Agora was originally created for Spanish utilities that lacked
the ability to provide real-time, guided solutions to utility operators
for avoiding and recovering from blackouts. Since its implementation
in 2000, the Agora tool has become an integral piece
of transmission operations at Endesa. Similarly, after the San
Francisco blackout of 1998, Pacific Gas & Electric recognized it
needed a solution to ensure it could restore customers as quickly
and safely as possible. Agora provided the needed real-time, dynamic
support for restoration.
In both of these instances, investments in analytical planning
software like Agora replaced outdated or unreliable intuition
with real-time information that helps operators respond to
emerging conditions to prevent a blackout or rapidly restore the
grid if a blackout occurs.
As we continue to add complexity and uncertainty to our
power grids, we must also develop and implement effective new
tools to help operators address these mounting concerns. The
restoration plans of yesterday, based largely on experience and
intuition, no longer make sense. By leveraging technology, operators
can improve the resiliency of the grid and reduce the
variables that prevent efficient restoration. ■
-Dr. Jason Black is a research leader in Battelle's Energy
Systems business and leads Battelle's transmission modeling
initiatives with Gridquant and the commercialization of Battelle's
demand-response management system.
www.powermag.com
POWER | November 2014
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POWER November 2014

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