IEEE Electrification Magazine - December 2013 - 37

TabLe 5. Generator selection, loading, and fuel consumption for the total load profile in Figure 11.
Region

Selected
Generator

None

5 kW

Duration
(h)
5

Generator
Load (kW)
5

Generator
Operating Point
100%

Fuel Flow
(gal/h)
0.57

Fuel Consumed
(gal)
2.9

15 kW

2.17

100%

1.23

2.7

15 kW

2.33

60%

0.83

1.9

5 kW

100%

0.57

2.9

5 kW

1.57

100%

0.57

0.9

None

Total

to provide power in times of low loading, meaning the
generators are shut off and not consuming any fuel. second, the battery pack's supplemental power allows a
15-kw generator to be substituted for the 20-kw generator in the traditional scenario. This is beneficial because
the 15-kw generator has a lower fuel flow than the 20-kw
generator for any given load. Third, the eMs only operates
one generator at a time. The chosen generator is the smallest option available that can power the loads while the
other generator is shut down. The data in Table 5 show
that the generators operate at 100% load most of the time.
in general, the generators' operating points are consistently higher than those shown in Table 2 for the traditional
method of generator employment.
The 24-h load profile used here might seem unrealistic,
i.e., a set of loads with a 20-kw peak requirement never
exceeded 9 kw in the notional power profile. surprisingly,
though, such underutilization is quite common. data collected in the field show that remote temporary bases contain as much as 115 kw of generator capacity for total
load profiles that, in reality, seldom reach above 45 kw.
The eMs serves a purpose in larger microgrid architectures above 20 kw as well. excessive generation capacity
drives traditional military generator employment, but in
reality, these generators never operate in the most efficient manner because doctrine limits them to 80% loading
at best. The use of an eMs enables generators to run up to
100% with the battery pack ensuring that additional
power is available when needed. The eMs may incorporate solar or wind power to charge the battery pack, alleviating some of that requirement from the generators.

For Further reading
B. frazee. (2010, feb.). energy symposium looks at reducing
the load in Marine Corps expeditionary operations, in U. s.
Marine Corps forces reserve. [online]. available: http://www.
marforres.marines.mil/Mfrnews/newsarticledisplay/
tabid/7930/article/81664/
G. oriti, a. L. Julian, and n. J. peck, "power electronics
enabled energy management systems," in Proc. IEEE

11.2

Applied Power Electronics Conf. and Expo., Long Beach, Ca,
Mar. 2013, pp. 3224-3231.
diesel service and supply. (2013). approximate diesel fuel consumption chart. [online]. available: http://
www.dieselserviceandsupply.com/ diesel_fuel_
Consumption.aspx
J. B. andriulli, a. e. Gates, H. d. Haynes, L. B. Klett, s. n.
Matthews, e. a. nawrocki, p. J. otaduy, M. B. scudiere, T. J.
Theiss, J. f. Thomas, L. M. Tolbert. M. L. Yauss, and C. a.
Voltz. (1999, nov.). advanced power generation systems for
the 21st century: Market survey and recommendations for
a design philosophy. oak ridge national Laboratory report
ornL/TM-1999/213. [online]. available: http://web.ornl.
gov/~webworks/cpr/v823/rpt/104704.pdf

biographies
Ryan L. Kelly (rkelly@usna.edu) earned the bachelor of
science degree in computer science from the U.s. naval
academy, annapolis, Maryland, in 2004 with a follow-up
assignment as a Marine Corps helicopter pilot. in 2013, he
earned the M.s.e.e. from the naval postgraduate school,
Monterey, California. He is currently serving as a military
faculty member of the department of Computer and
electrical engineering at the U.s. naval academy.
Giovanna Oriti (giovanna.oriti@ieee.org) is an associate professor in the electrical and Computer engineering department of the naval postgraduate school,
Monterey, California. Her research interests include
power converters modeling and design, eMi, energy
management, and electric ship systems. she is a senior
Member of the ieee.
Alexander L. Julian (ajulian@nps.edu) is an associate
professor in the electrical and Computer engineering
department of the naval postgraduate school, Monterey,
California. He contributed to shipboard electronic designs
and research for over 15 years by designing, modeling, and
prototyping power electronics and motion control systems
for many navy applications.

IEEE Electrific ation Magazine / d ec em be r 2 0 1 3

http://http:// http://www.dieselserviceandsupply.com/diesel_fuel_ http://www.web.ornl http://www http://marforres.marines.mil/Mfrnews/newsarticledisplay/

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