WP1: Project Management
The project activities are coordinated by the Project Coordinator (PC), who is
responsible for the management, the proper execution and overall monitoring of the
project’s technical and financial aspects. The Coordinator co-operates with the Research
Committee of NTUA, which, in turn, co-operates with the corresponding services of the
Ministry of Education. Thus, the PC resolves all the technical and financial issues emerging
during the execution of the project (contracts, payments, procurements etc).
For the proper execution of the project, coordination of each Work-Package, as well as of
each Work-Package Task, will be assigned to a member of the Research Team, who will be
the Work-Package/Task Leader, WpL and TL, respectively. WpL’s and TL’s are responsible
for the proper execution of their assignments, including the timely release of the
corresponding Deliverables. The PC along with the WpL’s and TL’s form the Project
Management Team (PMT). The other members of the Research Team work to the project
execution, following the guidelines of the PMT.
The coordination of each Work-Package and Task builds on the good communication
among the members of the Research Team (exchange of views and research results,
monitoring of Task execution and Deliverables etc.). All members of the PMT communicate
with one another on a weekly basis (via telephone and e-mail, and via the official
meetings). The official communication language is Greek, with English being an
alternative. All official documents will be in the official language set by the Hellenic
Ministry of Education.
Deliverable(s) / Milestone(s)

D.1.1: 1st Annual Report
D.1.2: 2nd Annual Report
D.1.3: Final Report
M.1.1: Project kick-off meeting
WP2: Initialization of project

T2.1: equipment procurement

Various software packages, already installed and functional at S-NAME/NTUA, will be
upgraded, in order to be utilized for the purposes of the project. These include PSCAD,
PORTUNUS, MOTORCAD and MATLAB/SIMULINK (see also the budget section). In addition, a
DC ship grid emulator will be purchased to accompany an already acquired state-of-the-art
AC ship grid, which is installed at S-NAME/NTUA, and is under the responsibility of the
Project Coordinator (see section discussing the resources to be committed). The power capacity of the
DC grid will be the same as the existing AC one, so that comparative performance tests
can be run in parallel (see WP5).

T2.2: data collection
Available data, which are essential for the simulation studies, such as energy demand in
distinct operating modes, electric balance, short-circuit analysis and grid configurations of
most commercial ship types where energy conservation is worthwhile, will be updated.
Ship types that will be included are LNG/LPG carriers, tankers, bulk carriers, container
ships, cruise ships, ro-ro ferries and reefers. Their distribution networks will be amended
into DC.

Deliverable(s) / Milestone(s)
D.2.1: Report on software upgrade and hardware procurement
D.2.2: Folder with updated ship data
M.2.1: Validation of procured (upgraded) software and hardware
WP3: Investigation of design considerations of DC systems as applied to commercial ships

T3.1: grid configurations

Based on the updated data of various ship types, as described in WP2, the generic grid
configuration will be adapted to each specific ship type. Different configurations of electric
power generation systems will be studied in order to select the voltage levels and the
various necessary components, based on the energy demand and the short circuit
capacity of each ship type. The aim of this Task is the analysis of the advantages and
disadvantages of these configurations, taking into account the relevant technical and
economic aspects under the light of environmental considerations (low emissions, energy
T3.2: main subsystems and components
In an All Electric Ship utilizing a DC distribution system, power electronics and electrical
machines are the main components necessary for the system operation. In addition, there
is a need for various other components and subsystems, such as DC circuit-breakers and
energy storage devices, which are required for the safe operation of the system. This task
will focus on assessing the operation of these components for each specific ship type,
based on the grid configuration. Furthermore the feasibility of utilizing Power Electronics
Building Blocks (PEBBs) will be assessed, using a simulation model. Regarding the design
stage of the power electronic converters, the use of modular components can result in
significant reduction of size, weight and cost, as well as on increased reliability. The
respective control of the various modules through the EPMACS will also be developed, so
as to be easily adopted in several different module-based designs, thus offering higher
flexibility and scalability.
Various types of electrical machines will be assessed for power generation, including
asynchronous generators, due to their simple and rugged construction.
The detailed models of DC electric ship subsystems and components will be combined to
form the full-scale model of the system, in order to demonstrate the aforementioned
operational advantages of this innovative topology. The overall model of the ship DC grid
as an Integrated Power System will be developed preferably in the combined platform of
PSCAD and Portunus. The model will be fully parameterized and generalized in order to
easily reproduce other similar DC electric ship configurations.
Deliverable(s) / Milestone(s)

D.3.1: Grid configurations for each specific ship type
D.3.2: Model of complete Integrated Power System with necessary
WP4: Investigation of considerations of operation of DC systems in commercial ships

T4.1 stability analysis

DC ship electric power systems are non-linear, time-varying, and subject to small and large
signal perturbations. Appropriate analysis should be performed to ensure that the system
regains a state of operating equilibrium after being subjected to a physical disturbance,
with most system variables bounded so that the entire system remains intact. In addition,
it has been shown that the nearly ideal regulation capability of modern power converters
may cause negative impedance instability. In this task a dynamic control system, ensuring
a generating-set highly responsive to variable power demand so that neither breaking
resistors, nor other damping devices are needed, will be designed and implemented. Using
the detailed model of the Integrated Power System, the operating behavior of the ship
electric system will be tested for various operating modes and disturbances. Apart from
steady state operation, system stability for small and large disturbances will be studied via
time and frequency domain simulations. Furthermore, one of the main advantages of the
proposed configuration, namely, frequency and voltage insensitivity to load fluctuations,
starts/stops of generators, propulsion drives and/or large consumers will be investigated
via extensive simulations.

T4.2 harmonic power quality analysis
Unlike the AC networks, in a DC system, the fundamental frequency is the zero one, while,
due to the power converters, harmonic distortion exists, too. Specifically, a solid state
power converter connected to a DC distribution bus draws a total line current of an
average DC current and some other frequency components, which are a function of the
converter internal switching frequency and the grid topology. In addition, any non-DC
component of load current flowing in the DC bus results in voltage ripple appearing at all
points along the bus. In the present Task, the impact of power converters on the DC power
bus (namely input and output voltage and currents of the DC power bus), as well as the AC
and DC power sources (namely their output voltage and currents) with regard to harmonic
power quality issues (total harmonic distortion, dominant harmonic, harmonic spectrum
and inter-harmonics), will be studied and evaluated via time-domain simulations.

T4.3 short-circuit fault analysis
In this Task, protection and fault detection algorithms will be included in the EPMACS of
the Integrated Power System model. In order to design adequate fault management for the
DC system and subsequently verify its performance, the response of the system
considering various types of faults in both AC and DC sub-systems and their combinations
will be studied. In all short circuit studies, a variety of fault impedances will be chosen such
that the entire spectrum of bolted faults, high impedance faults, and arcing faults will be
studied. Fault management studies will include studies to verify post-fault reconfiguration
to achieve restoration of service after a fault. The interaction between the system
protection and the ship EPMACS will be studied, in order to achieve fault detection and
isolation in the shortest time possible. Time domain computer system analysis will be
applied in all studies.

Deliverable(s) / Milestone(s)
D.4.1: Report of simulation results on system stability
D.4.2: Report of simulation results on power quality
D.4.3: Report of simulation results on short-circuit faults
WP5: DC vs AC ship electric grid emulations [months: 20-30]

T5.1 Experiments
This Task forms a novelty at an international level. Two circuits emulating the actual ship
grids, one operating with DC, and one operating with AC, will run, and their operation will
be measured, recorded and compared. Similar studies have started being performed, but
only for continental grids in USA [10]. Thus, the proposed research activity will, for the first
time, address the specific features of ship systems: smaller distribution network, but
higher number of industrial loads with highly compact power, few generators and many
rotating electric motors.
Several operational scenarios will be performed: partial loading w.r.t. rotating and/or
passive loads and energy supply by 1-3 generators; supply by 1/2/3 generator(s), loading
by 0%-100% loading of passive (resistive loads) and 0%-100% of rotating-active load.
Furthermore, some representative transient state operational scenarios, as materialized by
the analysis of WP4 (stability, power quality, faults) will also be performed, via the event
generator: e.g. grid emulators will be tested in transient sags and swells of pre-defined
amplitude (±3% – ±20%) and duration (0.5ms-5 ms). The measurements taken will
comprise time waveforms of voltage, current and power (instantaneous and rms values).
The present Task evidently builds on the equipment prescribed to be procured with the
project resources (DC-AES grid emulator and event generator).

T5.2 Evaluation of the experimental results
The recorded measurements in both DC-AES and AC-AES grid will be evaluated and
compared. Special emphasis will be put on electric power flows (active and reactive ones)
and losses, harmonic distortion levels (e.g. THD in voltage and current), voltage dips and
voltage restoration.

Deliverable(s) / Milestone(s)
D.5.1: Electronic Folder with measurements on DC-AES and ACAES
D.5.2: Report on measurement evaluation
M.5.1: Completion of measurements
WP6: DC ship maintenance, LCC and efficiency

T6.1 DC Power network maintenance
The present Task will focus on addressing the maintenance issues associated with the
various components (buses, converters, CB’s, motors, generators etc.), and on quantifying the
reliability of the components of a DC grid, using indices such as the Mean Time Between
Failure (MTBF). Via this approach, a Reliability Centred Planned Maintenance action plan
can be set, along with all the logistics of stocking and procuring spares and consumables
that can be integrated in the SEEMP (see Task 6.3).

T6.2 Life Cycle Cost analysis
A Life Cycle Cost (LCC) analysis of the DC ship grid will be performed, taking into account
procurement costs, operation costs and maintenance costs. In this analysis, the
anticipated benefits from using a DC system (e.g. lower losses that result in lower energy
demands, and in reduced emissions and increased fuel economy) will be quantified. LCC
analysis for a mean duration of most commercial ship types, i.e. 7-12 years, depending on
ship type, will be considered.

T6.3 Impact of DC implementation on ship efficiency
Exploiting the results of Tasks 6.1 and 6.2, the impact on ship efficiency, as evaluated
according to IMO directives, i.e. EEDI and EEOI, will be assessed for the ship types
considered and their transportation mission profiles. This includes the evaluation of fuel oil
consumption and related emissions produced by the equipment used to generate electric power
(e.g. thermal engines used as prime movers to electric generators). In particular, this will
be mainly based on the direct relationship, between produced electric energy and fuel
consumption on the one hand, as well as the produced GHG’s[1].

Deliverable(s) / Milestone(s)
D.6.1: Report on Maintenance of DC distribution network
D.6.2: Report on Life Cycle Cost study
D.6.3: Report on impact of DC on ship efficiency
WP7: Evaluation and Exploitation of results
In this (single-task) work-package the main project results will be exploited in two different
i) A set of rules (standard- and norm-like) will be formed.
ii) Principal conclusions will be formed in a way that can be integrated in the Ship Energy
Efficient Management Plan-SEEMP, recently introduced by IMO.
It is noted that, following the evaluation of the results, possibly needed small-scale
complementary studies, besides those described in WP3-WP6, will be performed within the
present Task.
Deliverable(s) / Milestone(s)
D.7.1: Report with propositions to exploit DC-Ship results
WP8: Dissemination of results
The results of the project will be disseminated to the international and national
scientific and maritime community via a series of activities as listed below:

T8.1: Webpage creation
The project results will be published in a dedicated webpage (www.ntua.gr/DC-Ship), which will
be kept updated on a continuous basis. The webpage will be hosted on the NTUA servers
for free (in accordance with NTUA’s policy). Hence, there is only the personnel cost of 3
person-months (1 per year) required for design, launching and maintenance of the

T8.2: Workshop organization
The interim results of DC-Ship, as well as new ideas and trends, will be discussed in a
Workshop organized around month 18 (mid-project). Five experts, 3 from Europe and 2
from overseas will be invited to participate in the Workshop (see also budget justification)
and give Keynote Lectures on modern DC ship energy sub-systems, while it is estimated
that approximately 50 participants will attend.

T8.3: Participation in Posidonia International Exhibition
The Posidonia exhibition takes place on a biannual basis during the first week of June, and
is one of the major international meetings of most maritime enterprises throughout the
Globe. The exhibition takes place in the wider region of Athens-Piraeus, the centre of the
Greek Maritime Community. Considering that January 1st, 2012 is considered the starting
date of the project, this dissemination event will take place at the Posidonia of 2014, i.e. in
the project month 30. In the course of Posidonia of 2014, the “DC-Ship” results will be
presented to the international maritime community in a special event (press-conference of
the Research Team accompanied by a light cocktail) organized within the Exhibition.

T8.4: Publications in journals and international conferences
The project results will be presented to international scientific fora via papers which will
either be presented in International conferences and/or published in peer-reviewed
journals. There is an estimate for 10 publications in conferences, 7 in Europe and 3
overseas. The publication cost to conferences is analyzed in the budget section. Further, it
is estimated that the project outcome will include a minimum of 2 journal papers.
The most appropriate International Conferences are:
International Naval Exhibition and Conference-INEC, All Electric Ship Symposium-AES,
Electric Ship Technology Symposium – ESTS (all organized biannually). Regarding the
advanced issues of electric machines and power electronics, dedicated conferences are
the International Conference of Electrical Machines – ICEM, the European Conference on
Power Electronics and Applications – EPE and the Power Electronics Specialists Conference
The following International journals are the most appropriate to publish the project results:
“The Journal of Marine Engineering & Technology” published by the Institute of Marine
Engineering, Science and Technology – IMarEST, and the “Electrical Systems in
Transportation” of the Institute of Engineering Technology – IET (the Project Coordinator,
John Prousalidis, is a member of the Editorial Board of both journals). Further appropriate
journals are: IEEE Transactions on Power Electronics, IEEE Transactions on Industry
Applications, IET Proceedings – Electric Power Applications.

Deliverable(s) / Milestone(s)
D.8.1: Project webpage
D.8.2: Report on Workshop on DC Systems
D.8.3: Report on participation in Posidonia International Exhibition
D.8.4: Folder of Conference and Journal papers
M.8.1: Project web-page launch
M.8.2: Organization of 1st Dissemination event and Workshop
M.8.3: Participation in Posidonia
[1] For instance, in case of Diesel Fuel Oil the GHG production is: 0.69 tCO2/MWh, 0.0139
tNOx/MWh, 0.0011 tSOx/MWh, 0.0004 tHC/MWh, 0.0003 tPM/MWh, while in case of Heavy
Fuel Oil: 0.722 tCO2/MWh, 0.0147 tNOx/MWh, 0.0123 tSOx/MWh, 0.0004 tHC/MWh,
0.0008 tPM/MWh.

By Marinelive on June 1, 2012