IEEE Power & Energy Magazine - March/April 2018 - 32

While the goal of reliability is to "keep the lights on,"
the goal of resiliency in the context of energy exchange is
to "keep the markets on" at all times.
One example is the study of the impact of gmds on the
high-voltage electric grid. gmds, which result from corona
mass ejections from the sun, cause low-frequency (much
lower than 0.1 Hz) variations in the earth's magnetic field.
the changing magnetic field then induces electric fields on
the earth's surface, with the magnitude and direction of
these electric fields determined by the conductivity of the
earth's crust going down several kilometers. these electric
fields then cause low-frequency, geomagnetically induced
currents to the flow in the high-voltage transmission system, potentially causing half-cycle saturation in the highvoltage transformers. a gmd with a maximum electric
field of about 2 V/km caused a blackout in Quebec, canada,
in 1989. much larger gmds occurred in north america in
1859 and 1921, with magnitudes estimated by some as being
up to five times those of the 1989 event. such a gmd occurring today could cause a severe event, with potentially longterm power outages.
the potential for gmds to impact the electric grid has
been known since at least the early 1940s, and the incorporation of gmd analysis within the power flow was first
proposed in 1981. However, power grid gmd assessment is
still an active area of research and development, with much
progress in the last few years through interdisciplinary work and
active industry and government involvement. as a result,
gmd analysis has now been integrated into commercial
power system planning tools, including power flow and transient stability analysis software. However, determining the
magnitudes of the severe events to model can be challenging because historical records are often incomplete or nonexistent. determining the scenarios to consider for humancaused severe events, such as a combined cyber and physical
attack, is even more challenging.

Resiliency in Operations
and Operations Planning:
Visualizing Massive Amounts of data
in addition to planning considerations, much can be done
in the area of real-time operations of the electric grid to
enhance resiliency. With the advent of the smart grid, the
electric grid is getting more intelligent, offering more sensing and embedded controls. this is certainly beneficial, but
a consequence is increased grid complexity. While this automatic control is helpful, any consideration of power system
operations needs to recognize that human operators are still
very much "in the loop" and will continue to be so for many
years. therefore, enhanced operational resiliency needs to
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consider tools to enhance the capabilities of the operators
and engineers running the system.
One of the undesirable consequences of large-scale interconnects is that disturbances in one portion of the system can
rapidly affect the entire system. the normal operating state
can rapidly become an emergency or in extremis state, during which quick, informed intervention by a human operator
is essential. Hence, operators need to maintain situational
awareness. as shown by the loss of situational awareness
that was one cause of the 14 august 2003 north america
blackout, there is a need to develop better techniques to help
human operators manage the unique operating challenges
posed by in extremis conditions. a key resiliency need in
the operations area is better data analytics and visualizations
to help operators manage the potentially quite unusual conditions they might encounter during in extremis situations.
the degree to which operator action can prevent or minimize a blackout depends on the severity of the event and its
time frame. some large-scale blackouts cannot be prevented
by operator action. For example, during an earthquake, an
unanticipated event can cause severe damage within seconds.
Here, visualization would be most helpful in the restorative
state because there is nothing the operator can do to prevent
physical damaged due to an earthquake. conversely, slowmoving weather systems, such as hurricanes or ice storms,
give operators plenty of time to act, but blackouts still cannot
be fully prevented. For example, 2102's superstorm sandy
in the eastern United states caused 8.5 million customer
power outages with damage estimated at $Us65 billion.
many, if not most, potential large-scale blackouts have time
frames that could allow for effective operator intervention. a primary reason for this is the underlying power system dynamics,
including the time constants associated with thermal heating on
transmission lines and transformers, the operation of load-tapchanging transformers, and generator overexcitation limiters.
during the unusual situations associated with severe events,
wide-area power system visualization will be crucial for providing operators and engineers with the big picture of a grid that
may be operating in a state they have not previously encountered.
there may be multiple electric islands, transmission line flows
may differ substantially from normal, and the voltage profile
could be quite unusual.
Over the years, much has been done in power system analytics and visualization to improve situational awareness, and
this remains an active area of research. While a full discussion is beyond the scope of this article, one approach that
has been helpful is the use of dynamically formatted one-line
march/april 2018

Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - March/April 2018