IEEE Power & Energy Magazine - July/August 2016 - 39

the expected cost savings resulting from adaptive planning,
demonstrate that it can be both feasible and cost-effective to
consider uncertainty in a stochastic planning tool. however,
using present computing technology, there are limits to the
complexity that can be represented-consideration of more
than 300 aggregated buses, 24 representative hours/year, and
20 scenarios strained the capabilities of our workstations. as
computational capabilities improve, the models can be made
more realistic by considering more buses, hours, and scenarios
and by improving the realism of the models.
here are some ways in which the realism of the models
can be improved.
✔ An enlarged pool of candidate lines. In a linearized
dc model, each line in each year and scenario is represented by a binary variable, and the number of binaries that can be considered in our mixed-integer linear
programming-based formulation is relatively limited.
✔ Generation unit commitment constraints. with the
higher penetration of variable renewables, flexibility
of fossil generation becomes a greater concern, and it
becomes more important to represent start-up costs,
minimum output constraints, and other details of unit
commitment.
✔ More decision stages. figure 1 shows a two-stage
problem in which all uncertainties are eliminated by
the second stage. however, in reality, uncertainties remain in the future, while there are also intermediate
decision stages that give the system more flexibility,
such as obtaining permits for a corridor before committing to construction.
✔ Enhanced dc load flow with losses, ac load-flow models, and flexible ac transmission system devices. modeling these would more accurately represent the costs of
transmission as well as options to manage those costs.
The inclusion of some or all of these features would enable
stochastic planning models to provide even more useful
insights to the planning process.

Acknowledgments
This material is based upon work supported by the western
electricity Coordinating Council and by the U.s. department
of energy, office of electricity delivery and energy reliability, through a contract managed by the lawrence berkeley
national laboratory. partial support was also provided by the
Consortium for electricity reliability Technology solutions
of the U.s. department of energy. The project team would
like to thank weCC staff and the members of the Technical advisory Committee for their advice and input. reference
herein to any specific commercial product, process, or service
by trade name, trademark, manufacturer, or otherwise does
not necessarily constitute or imply its endorsement, recommendation, or favoring by the United states government or
any agency thereof. our views and opinions expressed herein
do not necessarily state or reflect those of the United states
government or any agency thereof.
40

ieee power & energy magazine

For Further Reading
J. ho, b. f. hobbs, p. donohoo-Vallett, Q. Xu, s. Kasina,
s. w. park, and y. ouyang. (2015). planning transmission
for uncertainty: applications and lessons for the western
interconnection. weCC. The Johns hopkins University.
[online]. available: www.wecc.biz/reliability/planning-forUncertainty-final-report.pdf
V. Krishnan, J. ho, b. f. hobbs, a. l. liu, J. d. mcCalley,
m. shahidehpour, and Q. p. Zheng, "Co-optimization of electricity transmission and generation resources for planning
and policy analysis: review of concepts and modeling approaches," Energ. Syst., vol. 7, no. 2, pp. 297-332, may 2016.
s. lumbreras and a. ramos, "The new challenges to
transmission expansion planning: survey of recent practice
and literature review," Electric Power Syst. Res., vol. 134,
pp. 19-29, may 2016.
f. d. munoz, b. f. hobbs, J. ho, and s. Kasina, "an engineering-economic approach to transmission planning under market and regulatory uncertainties: weCC case study,"
IEEE Trans. Power Syst., vol. 29, no. 1, pp. 307-317, dec. 2014.
J. pfeifenberger, J. Chang, and a. sheilendranath. (2015).
Toward more effective transmission planning: addressing
the costs and risks of an insufficiently flexible electricity
grid. The brattle Group. [online]. available: http://wiresgroup.com/docs/reports/wIres%20brattle%20rpt_Transplanning_042315.pdf
e. sauma and s. oren, "economic criteria for planning
transmission investment in restructured electricity markets,"
IEEE Trans. Power Syst., vol. 30, no. 4, pp. 1394-1405, nov.
2007.
a. h. van der weijde and b. f. hobbs, "The economics
of planning electricity transmission to accommodate renewables: Using two-stage optimization to evaluate flexibility
and the cost of disregarding uncertainty," Energy Econ., vol.
34, no. 6, pp. 2089-2101, nov. 2012.

Biographies
Benjamin F. Hobbs is with Johns hopkins University, baltimore, maryland.
Qingyu Xu is with Johns hopkins University, baltimore,
maryland.
Jonathan Ho is with the national renewable energy
laboratory, Golden, Colorado.
Pearl Donohoo is with the brattle Group, washington, d.C.
Saamrat Kasina is with Johns hopkins University, baltimore, maryland.
Jasmine Ouyang is with ethree, san francisco, California.
Sang Woo Park is with Johns hopkins University, baltimore, maryland.
Joseph Eto is with the lawrence berkeley national laboratory, berkeley, California.
Vijay Satyal is with the western electricity Coordinating
Council, salt lake City, Utah.
p&e

july/august 2016

http://www.wecc.biz/reliability/planning-for http://wires http://www.group.com/docs/reports/wIres brattle rpt_Trans

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