IEEE Electrification Magazine - June 2016 - 55

Management Plan (SEEMP) to encourage emissions limitation, and it may
be required for each vessel in the near
future. To design a SEEMP, it is possible to employ advanced offline optimization algorithms to improve the
fuel-saving effect with reasonable
assumptions (i.e., the fuel efficiency is
affected only by engine speed and
load). However, the practical operation
of a vessel may be influenced by innumerable contingencies (e.g., unexpected travel distance due to wind and
waves), which make the offline predesigned SEEMP result in suboptimal
fuel efficiency. To maximize fuel efficiency and/or minimize emissions, a
potential method is to combine scenario-based multimode
control and real-time optimization, in which real-time
optimizing could be done within the constraints given by
the tertiary level of hierarchical control (i.e., the energy
management level) and according to the detailed system
status (i.e., the overall state of charge information from
the ESSs and the operation mode).
To implement a SEEMP, joint management, on both the
generation side and demand side, is required. From the
perspective of generation, a dc distribution system allows
each prime mover to operate independently in a variablespeed mode without the limitation of synchronization. Figure 10 shows an experimental result of the specific fuel oil
consumption (SFOC) in g/kWh under the full operating
range of a typical shipboard diesel generator. It indicates
that fuel consumption is a nonlinear function of the
engine speed and load condition and has a high-efficiency
area. Generally, the generation-side management tends to
keep the onboard generators either working in their highefficiency area or working in idle speed. In this way, the
SFOC is maintained at its lowest point. However, the
onboard generation is not stand-alone; it always depends
on the power demand.
The traditional demand-side management method in
power systems is based on load shedding methods. However, the onboard loads are usually mission oriented, and
the major energy consumer will be the electric propulsion
system in the future AES. Thus, conventional load shedding will result in unwanted performance degradation in
mission-oriented function or the propulsion system,
which makes the methods unsuitable for such coordinated management. With the help of ESSs, the dynamic
active power balance can be achieved by properly and
bidirectionally managing the power flow between ESSs
and the dc bus. Thus, an equivalent demand-side management can be achieved in this way, which allows highly
flexible operation of the other onboard electrical equipment. At the same time, the major optimization objectives, such as maximum fuel efficiency and support of

In small-scale dc
microgrids, each
unit can be directly
regulated by the
central controller
via high-bandwidth
communication
using the master/
slave method.

emerging pulsed mission-oriented
equipment, can also be achieved.
The role of ESSs in the SEEMP is
extremely important due to their
invaluable bidirectional characteristic.
The presence of ESSs breaks the conventional dependency between the
generation side and demand side,
thus significantly improving the flexibility of the SEEMP. In addition, it is
noteworthy that the electric propulsion could also act as generation
while doing regenerative braking. The
traditional method is not able to deal
with such bidirectional loads, and the
excess energy has to be dissipated on
dumping resistors to maintain the
stability of the power system. With the help of ESSs, this
part of the energy can be partly or fully stored, thus helping to reduce the overall cost. ESSs are also able to take the
role of the primary energy resource during short-term
voyages (e.g., in-port moving) or emergency conditions
(i.e., auxiliary generation), which may significantly reduce
the environmental impact and enhance reliability.

Smart Protection and Reconfiguration for
Fault-Tolerant and Highly Reliable Systems

100

212
210
208
206
204
202
200
198

Torque (%)

90
80
70
60
50
40

SFOC (g/kWh)

The protection of dc power systems, especially those with
complex dc ZEDS configurations, is a challenging task
requiring the development of SSCBs suitable for MVdc
solutions and complex coordination between power converters and protective functions. Moreover, compared with
conventional transformers, the instantaneous overcurrent
capability of power electronic converters must be limited
to avoid equipment damage, whereas conventional transformers inherently carry a reserve inertia to sudden transient electrical events. As a result, an adequate shipboard
IPS, which delivers power through power electronic converters, usually leads to overdesign of the power electronic
equipment, which is a problem when considering space

Engine Speed (r/min)

98
1, 0
00
0

88
0
90
0
92
0
94
0
96
0

82
0
84
0
86
0

196

Figure 10. The SFOC of a typical diesel engine at variable speed
and torque.

IEEE Electrific ation Magazine / j une 2 0 1 6

55



Table of Contents for the Digital Edition of IEEE Electrification Magazine - June 2016

IEEE Electrification Magazine - June 2016 - Cover1
IEEE Electrification Magazine - June 2016 - Cover2
IEEE Electrification Magazine - June 2016 - 1
IEEE Electrification Magazine - June 2016 - 2
IEEE Electrification Magazine - June 2016 - 3
IEEE Electrification Magazine - June 2016 - 4
IEEE Electrification Magazine - June 2016 - 5
IEEE Electrification Magazine - June 2016 - 6
IEEE Electrification Magazine - June 2016 - 7
IEEE Electrification Magazine - June 2016 - 8
IEEE Electrification Magazine - June 2016 - 9
IEEE Electrification Magazine - June 2016 - 10
IEEE Electrification Magazine - June 2016 - 11
IEEE Electrification Magazine - June 2016 - 12
IEEE Electrification Magazine - June 2016 - 13
IEEE Electrification Magazine - June 2016 - 14
IEEE Electrification Magazine - June 2016 - 15
IEEE Electrification Magazine - June 2016 - 16
IEEE Electrification Magazine - June 2016 - 17
IEEE Electrification Magazine - June 2016 - 18
IEEE Electrification Magazine - June 2016 - 19
IEEE Electrification Magazine - June 2016 - 20
IEEE Electrification Magazine - June 2016 - 21
IEEE Electrification Magazine - June 2016 - 22
IEEE Electrification Magazine - June 2016 - 23
IEEE Electrification Magazine - June 2016 - 24
IEEE Electrification Magazine - June 2016 - 25
IEEE Electrification Magazine - June 2016 - 26
IEEE Electrification Magazine - June 2016 - 27
IEEE Electrification Magazine - June 2016 - 28
IEEE Electrification Magazine - June 2016 - 29
IEEE Electrification Magazine - June 2016 - 30
IEEE Electrification Magazine - June 2016 - 31
IEEE Electrification Magazine - June 2016 - 32
IEEE Electrification Magazine - June 2016 - 33
IEEE Electrification Magazine - June 2016 - 34
IEEE Electrification Magazine - June 2016 - 35
IEEE Electrification Magazine - June 2016 - 36
IEEE Electrification Magazine - June 2016 - 37
IEEE Electrification Magazine - June 2016 - 38
IEEE Electrification Magazine - June 2016 - 39
IEEE Electrification Magazine - June 2016 - 40
IEEE Electrification Magazine - June 2016 - 41
IEEE Electrification Magazine - June 2016 - 42
IEEE Electrification Magazine - June 2016 - 43
IEEE Electrification Magazine - June 2016 - 44
IEEE Electrification Magazine - June 2016 - 45
IEEE Electrification Magazine - June 2016 - 46
IEEE Electrification Magazine - June 2016 - 47
IEEE Electrification Magazine - June 2016 - 48
IEEE Electrification Magazine - June 2016 - 49
IEEE Electrification Magazine - June 2016 - 50
IEEE Electrification Magazine - June 2016 - 51
IEEE Electrification Magazine - June 2016 - 52
IEEE Electrification Magazine - June 2016 - 53
IEEE Electrification Magazine - June 2016 - 54
IEEE Electrification Magazine - June 2016 - 55
IEEE Electrification Magazine - June 2016 - 56
IEEE Electrification Magazine - June 2016 - 57
IEEE Electrification Magazine - June 2016 - 58
IEEE Electrification Magazine - June 2016 - 59
IEEE Electrification Magazine - June 2016 - 60
IEEE Electrification Magazine - June 2016 - 61
IEEE Electrification Magazine - June 2016 - 62
IEEE Electrification Magazine - June 2016 - 63
IEEE Electrification Magazine - June 2016 - 64
IEEE Electrification Magazine - June 2016 - 65
IEEE Electrification Magazine - June 2016 - 66
IEEE Electrification Magazine - June 2016 - 67
IEEE Electrification Magazine - June 2016 - 68
IEEE Electrification Magazine - June 2016 - 69
IEEE Electrification Magazine - June 2016 - 70
IEEE Electrification Magazine - June 2016 - 71
IEEE Electrification Magazine - June 2016 - 72
IEEE Electrification Magazine - June 2016 - Cover3
IEEE Electrification Magazine - June 2016 - Cover4
http://www.nxtbook.com/nxtbooks/pes/electrification_december2019
http://www.nxtbook.com/nxtbooks/pes/electrification_september2019
http://www.nxtbook.com/nxtbooks/pes/electrification_june2019
http://www.nxtbook.com/nxtbooks/pes/electrification_march2019
http://www.nxtbook.com/nxtbooks/pes/electrification_december2018
http://www.nxtbook.com/nxtbooks/pes/electrification_september2018
http://www.nxtbook.com/nxtbooks/pes/electrification_june2018
http://www.nxtbook.com/nxtbooks/pes/electrification_december2017
http://www.nxtbook.com/nxtbooks/pes/electrification_september2017
http://www.nxtbook.com/nxtbooks/pes/electrification_march2018
http://www.nxtbook.com/nxtbooks/pes/electrification_june2017
http://www.nxtbook.com/nxtbooks/pes/electrification_march2017
http://www.nxtbook.com/nxtbooks/pes/electrification_june2016
http://www.nxtbook.com/nxtbooks/pes/electrification_december2016
http://www.nxtbook.com/nxtbooks/pes/electrification_september2016
http://www.nxtbook.com/nxtbooks/pes/electrification_december2015
http://www.nxtbook.com/nxtbooks/pes/electrification_march2016
http://www.nxtbook.com/nxtbooks/pes/electrification_march2015
http://www.nxtbook.com/nxtbooks/pes/electrification_june2015
http://www.nxtbook.com/nxtbooks/pes/electrification_september2015
http://www.nxtbook.com/nxtbooks/pes/electrification_march2014
http://www.nxtbook.com/nxtbooks/pes/electrification_june2014
http://www.nxtbook.com/nxtbooks/pes/electrification_september2014
http://www.nxtbook.com/nxtbooks/pes/electrification_december2014
http://www.nxtbook.com/nxtbooks/pes/electrification_december2013
http://www.nxtbook.com/nxtbooks/pes/electrification_september2013
http://www.nxtbookMEDIA.com