IEEE Electrification Magazine - June 2015 - 26

Start
SFC (g/kWh)

Load Analysis
Determination of Number
and Size of Generator Sets

SDG (1 MW)
LDG (2.5 MW)

5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110

Increment Power Capacity of BESS

450
400
350
300
250
200
150
100
50
0

Load Factor (%)

Defining Operation Mode of Generator Sets

Figure 4. The SFC curves of engine generators.

Computation of Annual Fuel Consumption
Possibility of
BESS Installation

No

Yes
Final Decision of BESS Capacity
Finish
Figure 3. The flow chart to design the BESS capacity.

where PG.total is the total generation power of the online generators and PG.trip is the power loss caused by the largest
online generator failure. LFsafe should be a positive number
for a fail-safe operation, and the larger LFsafe refers to higher
fuel efficiency. The output power of each generator PGi is
restricted as in (2) under the assumption of a same load
ratio among engine generators regardless of their capacity
PGi # LFsafe # PGi.max .

(2)

The operation concept can be explained with an example ship constructed by the Republic of Korea Navy. This
ship has four DE-generators (DGs): two 1-MW small DGs
(SDG1, SDG2) and two 2.5-MW large DGs (LDG1, LDG2).
Every possible engine generator combination is listed in
Table 1. Sustainable load stands for the maximum sustainable load after the loss of the largest online generator. For
the fail-safe operation, a load connected to the grid cannot
exceed the corresponding sustainable load value of each
combination. For example, #5 can be in operation only
when the load is less than 2 MW. Among the eight combinations, #1 and #2 cannot be allowed because of zero LFsafe .
PG.total - PG.trip
LFsafe =
# 100,
(1)
PG.total
Also, #4 is not a good option because it has the same sustainable load as #2 but a smaller
load factor. The allowed combinations are shaded, and the operTable 1. An example of engine-Generator Combinations
ation region of each combination
for Safe Operation (x Corresponds to 1 or 2).
lies within its sustainable load
Combination of
Total Power
Sustainable Load
values while the available maxiEngine-Generators
(PG.total, MW)
(MW)
LFsafe (%)
mum load factor for the fuel
economy is maintained. Accord1
(N.A.) 0
0
#1 (SDGx)
ing to this principle, #5 can oper2
50
1
#2 (SDG1, 2)
ate with the load between 1 and
2.5
(N.A.) 0
0
#3 (LDGx)
2 MW. Because a load of more
than 4.5 MW cannot be sustained
3.5
28.6
1
#4 (SDGx+ LDGx)
against engine-generator failure,
4.5
44.4
2
#5 (SDG1, 2 +LDGx)
appropriate and immediate load
5
50
2.5
#6 (LDG1, 2)
shedding is necessary to keep the
IPS in operation.
6
58.3
3.5
#7 (SDGx+ LDG1, 2)
The presence of an additional
7
64.3
#8 (SDG1, 2 + LDG1, 2)
4.5
power source such as the BESS

The first procedure related to N-1 safety determines the
allowed engine-generator sets, while the second procedure related to MGO calculates the fuel savings and BESS
cost. Finally, the BESS capacity is determined after the iterations of these two procedures, as shown in a flow chart
in Figure 3.
The N-1 safety completion can be distinguished by the
load factor for safe operation, LFsafe, according to the
online generators as

26

I E E E E l e c t r i f i c ati o n M agaz ine / j un e 2015



Table of Contents for the Digital Edition of IEEE Electrification Magazine - June 2015

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IEEE Electrification Magazine - June 2015 - Cover3
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https://www.nxtbook.com/nxtbooks/pes/electrification_december2022
https://www.nxtbook.com/nxtbooks/pes/electrification_september2022
https://www.nxtbook.com/nxtbooks/pes/electrification_june2022
https://www.nxtbook.com/nxtbooks/pes/electrification_march2022
https://www.nxtbook.com/nxtbooks/pes/electrification_december2021
https://www.nxtbook.com/nxtbooks/pes/electrification_september2021
https://www.nxtbook.com/nxtbooks/pes/electrification_june2021
https://www.nxtbook.com/nxtbooks/pes/electrification_march2021
https://www.nxtbook.com/nxtbooks/pes/electrification_december2020
https://www.nxtbook.com/nxtbooks/pes/electrification_september2020
https://www.nxtbook.com/nxtbooks/pes/electrification_june2020
https://www.nxtbook.com/nxtbooks/pes/electrification_march2020
https://www.nxtbook.com/nxtbooks/pes/electrification_december2019
https://www.nxtbook.com/nxtbooks/pes/electrification_september2019
https://www.nxtbook.com/nxtbooks/pes/electrification_june2019
https://www.nxtbook.com/nxtbooks/pes/electrification_march2019
https://www.nxtbook.com/nxtbooks/pes/electrification_december2018
https://www.nxtbook.com/nxtbooks/pes/electrification_september2018
https://www.nxtbook.com/nxtbooks/pes/electrification_june2018
https://www.nxtbook.com/nxtbooks/pes/electrification_december2017
https://www.nxtbook.com/nxtbooks/pes/electrification_september2017
https://www.nxtbook.com/nxtbooks/pes/electrification_march2018
https://www.nxtbook.com/nxtbooks/pes/electrification_june2017
https://www.nxtbook.com/nxtbooks/pes/electrification_march2017
https://www.nxtbook.com/nxtbooks/pes/electrification_june2016
https://www.nxtbook.com/nxtbooks/pes/electrification_december2016
https://www.nxtbook.com/nxtbooks/pes/electrification_september2016
https://www.nxtbook.com/nxtbooks/pes/electrification_december2015
https://www.nxtbook.com/nxtbooks/pes/electrification_march2016
https://www.nxtbook.com/nxtbooks/pes/electrification_march2015
https://www.nxtbook.com/nxtbooks/pes/electrification_june2015
https://www.nxtbook.com/nxtbooks/pes/electrification_september2015
https://www.nxtbook.com/nxtbooks/pes/electrification_march2014
https://www.nxtbook.com/nxtbooks/pes/electrification_june2014
https://www.nxtbook.com/nxtbooks/pes/electrification_september2014
https://www.nxtbook.com/nxtbooks/pes/electrification_december2014
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