1

Integration, optimisation and benefits of

energy storage for marine applications

Dr Damir Radan, PhD MIEEE

Martin Southall, MSc CEng FIET

Dr Makhlouf Benatmane, BSc(Hons) PhD CEng FIMarEST FIET

Martin Butcher, CEng MIET

GE Power Conversion

This technical paper is prepared for the purposes of the 2016 International Naval Engineering

Conference (INEC). It is based on the author’s opinion and information collected through various

sources. Many variables may impact the technical considerations and data as well as the study results

illustrated in the documents; GE’s intention is only to give examples of potential applications and

related impact of certain enhanced technology and products and these technical documents are not

meant to provide any guarantee relating to any conclusions and technical data contained herein. This

technical paper shall not be reproduced nor the content used for different purposes.

SYNOPSIS

The marine & offshore industry is recognising the potential for Energy Storage Systems (ESS) on vessels with

variable operating profiles, fluctuating loads to provide efficiency & reliability improvements, reduction in fuel

consumption and emissions. Recent technological advancements and continuing cost reductions put the focus on

Lithium-ion battery or Ultra Capacitor based ESS where the main benefits are high specific energy in kJ/kg and

ability to support cyclic operations. However, as the number of cycles and the depth of the discharge increases,

the lifetime of ESS, especially if battery based, significantly reduces meaning that ESS may not be optimally

utilised. Furthermore, operators are giving more priority to engine maintenance schedules optimisation, by

trending analysis and necessity to reduce the number of operating hours. With coordination of ESS systems,

these engines can deliver lower life-cycle costs, greater uptime, improved reliability and higher availability.

Coupled to this, is the understanding of converter technology, integrated into ‘off grid’ multi-generator systems,

improved understanding of integrated solutions to meet demanding network power requirements whilst

maintaining reliability, dynamic performance and classification requirements. This requires careful consideration

of the overall system, converters, supporting passive components and their correct application as a system.

This paper provides an overview of potential applications and describes control strategies used and then

considers methods to improve the available technologies related to power system control and protection, diesel

engine response to network fluctuations, and design of modern E-storage systems. This paper will also present

the multiple energy store configuration, the main challenges and top level topologies considered to meet these

requirements.

INTRODUCTION

Modern marine power systems are required to be designed based on challenging performance criteria,

classification society rules and legislative constraints. These requirements challenge industry to evolve, in search

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for improved methods of vessel design and operation. The latest class society rules allow for Energy Storage

System “ESS” to be considered as redundant source of power or replace a main source of power [1]. Guidelines

provided are based on experience with current installations [2] and [3].

Lowering operating costs enhances the competitiveness of vessels for ship-operators e.g. reduced fuel

consumption, maintenance costs, and exhaust gas emissions in all operating modes being transit, dynamic

positioning “DP” and harbour. Available technology enables enhancements in vessel performance and safety.

Using ESS, the propeller(s) thrust set by DP control and propulsion system can quickly be available the vessel

becomes more responsive. This improved response also provides improved system stability.

According to [4], if no actions are taken, exhaust gas emissions from shipping will double by 2030. This trend is

based on expectance of increase in trade volume combined with the moderate carbon policy and the low uptake

of low carbon fuels.

International Marine Organisation (IMO)’s scheme for reduction of NOx emissions in the environmentally

sensitive areas, so called Emission Control Areas (ECAs) specifies the limits for marine engine emissions.

Restrictions imposed on ship-owners by the IMO force them to invest either in “cleaner fuel” marine gas oil or

marine diesel oil with their storage facilities and/or installations cleaning the exhaust or alternatively in

installations for storage and burning of the cleanest fossil fuel, i.e. natural gas [5].

By observing required load ramp up requirements for various type of engines one can notice that transient load

acceptance for gas or duel fuel engine is generally lower than for the diesel engine. Paralleling more generators

will reduce the load response per individual engine which results in operating more generators online at low

average load. Low load running for both diesel and gas or dual-fuel engines is generally considered to be the

area of low efficiency, and increased maintenance and exhaust gas emissions.

On some diesel engines it is typically not recommended running engines at low load longer than a limited

amount of time e.g. below 20% for 100 hours [7]. It is suspected that operations at low loads combined with

transient loads increase operational problems [8].

Described requirements open up various technological advancements in marine power systems, encouraged by

similar technologies e.g. electrical vehicles (EV) and micro-grids. Ship operators are more receptive to

alternative environmental-friendly solutions which can provide operating cost savings and enhanced vessel

performance.

MARINE APPLICATIONS FOR ENERGY STORAGE

Main benefits of Energy Storage System (ESS)

Inspired by similar solutions in other technologies, ESS solutions can provide key benefits in marine domain:

Running lower numbers of generators online at higher load due to reducing limits for spinning reserve.

ESS acts as additional power reserve providing available power in case of generator failure for a

predetermined duration.

Improves system stability caused by slow response of engines to load demand.

Reducing thrusters load ramp limits and enabling quickly available thrust force. This enables vessel fast

responsiveness and enhances manoeuvring capabilities, thus increasing safety.

Similar to emergency generator, ESS can reduce power system vulnerability to faults in externally

supported systems. Thus reduced need for non-electric e.g. shaft-attached mechanical and pneumatic

systems is

Reduces operating costs due to optimised fuel consumption and lowers engine maintenance.

Reduces the risk of blackout by operating ESS as Uninterruptable Power Supply (UPS), and in case of

blackout enables quick power system recovery, faster than when emergency generators are used.

Depending on the operating load profile, ESSs can reduce the number of generator start/stops. It can also

make power available during start-up of stand-by generator(s).

Qualitative benefits for power management and system performance enhancements could be very significant,

and to some applications even more important than OPEX savings.

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If applied, enhanced bus synchronization using ESS reduces the risk of mal-synchronization during switching

between isolated and interconnected bus modes and allows using intelligent auto-reconfigurable system.

Operating in isolated bus mode has advantage of reducing fault level when the system load is high and mitigates

the risk of fault propagation between the zones.

By fast load levelling capabilities, ESS can support power sources with slow responses. This can enable higher

availability of power to consumers without unnecessary delay required for starting stand-by generator(s).

Figure 1 shows general possibilities for marine application of currently available ESS technology. The future

trend indicates the availability of higher charge and discharge rates i.e. higher power due to improved battery,

super/ultra-capacitor, flywheel and ultimately fuel cell[11]

technology to enhance vessel operation on low

emission energy sources.

Modern li-ion battery technology has shown to be of great advantage due to its increase specific energy; specific

power and with very high efficiency, expected to increase further in the future... Major drawback is the

degradation over time, or calendar lifetime compared to other components in the system.

The advantage of fly-wheel and super-capacitor technology is mainly for applications requiring highly dynamic

load variation, and low degradation over time due to change of material properties. The cost of battery

technology is generally in decline. The safety precautions with lithium-ion batteries are taken into consideration

by all major battery manufacturers, converter control, and classification societies in requirements for the

installation, control and interlocking [1], [2], [3].

Figure 1 –– Marine application technology trends for ESS and low emission technology: required installed kWh to deliver power

ESS application for blackout prevention and blackout recovery

In power reserve mode or blackout prevention mode, the ESS operates with two or more paralleled gen-sets. In

case of overload caused by tripping of one or more gen-sets, ESS covers for loss of available power and

stabilises online gen-sets until the standby gen-sets is brought online. Duration of support will depend on the size

of ESS and its available energy.

Table I shows an example of load generator limit when the system is operated without and with ESS. The

example in the table is presented for illustration only – detailed studies should be performed based on DP

Capability and load balance sheet to estimate exact load per bus before and after the fault.

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The load limit for connected generating system can be calculated according to:

𝑃𝐺,𝑙𝑖𝑚𝑖𝑡 = ∑ 𝑃𝑔𝑛,𝑁 + ∑ 𝑃𝐸𝑆𝑆 − ∑ 𝑃𝑔𝑛,𝑁𝑓𝑎𝑖𝑙 , [kW] (1)

Assuming generators share load equally as required by class societies, the load limit for individual generator can

be expressed as a ratio of generator nominal load, according to:

𝛽𝑔,𝑙𝑖𝑚𝑖𝑡 = 𝑃𝐺,𝑙𝑖𝑚𝑖𝑡

∑ 𝑃𝑔𝑛,𝑁, (per unit) (2)

Where

𝑃𝑔,𝑙𝑖𝑚𝑖𝑡 [kW]- online generating system load limit

𝛽𝑔,𝑙𝑖𝑚𝑖𝑡 [p.u.]- online load limit for individual generator

∑ 𝑃𝑔,𝑁 [kW]- total generating capacity connected online to the same bus with ESS

∑ 𝑃𝐸𝑆𝑆 [kW]- total ESS capacity connected online to the same bus with generators

∑ 𝑃𝑔,𝑁 [kW]- generating capacity not-connected to the bus after the failure

𝑁𝑂𝑁 - total number of generators online before the failure

𝑁𝑓𝑎𝑖𝑙 - number of generators not connected after the failure

𝑃𝐸𝑆𝑆 [kW] - Individual ESS capacity to support the load for specified time duration

In this example, all generators are of equal size. If ESS is not in use and two gen-sets online then the power limit

at gen-sets is 𝛽𝑔,𝑙𝑖𝑚𝑖𝑡= 50%. The power reserve in Table I is equivalent to 100% nominal power of single gen-set

in order to support its loss in case of failure [9]. In the example ∑ 𝑃𝐸𝑆𝑆 /𝑃𝑔𝑛 = 50%, so total ESS capacity is 50%

of single generator capacity. With ESS added in the power capacity in eq (1), power management allows running

individual generators at 75% load limit when ≥2 gen-sets are connected.

Table I –System capability for Power reserve mode with and without ESS

Failure mode: Loss of 1 gen

𝑵𝑶𝑵 𝑵𝒇𝒂𝒊𝒍 = 𝟏 𝛽𝑔,𝑙𝑖𝑚𝑖𝑡

w/o ESS

∑ 𝑃𝐸𝑆𝑆 /𝑃𝑔𝑛 𝑷𝒈,𝒍𝒊𝒎𝒊𝒕

with ESS

(-) (%) (%) (%)

2 1 50.0% 50.0% 75.0%

3 1 66.7% 50.0% 83.3%

4 1 75.0% 50.0% 87.5%

5 1 80.0% 50.0% 90.0%

6 1 83.3% 50.0% 91.7%

Failure mode: Loss of 2 gen

𝑵𝑶𝑵 𝑵𝒇𝒂𝒊𝒍 = 𝟐 𝛽𝑔,𝑙𝑖𝑚𝑖𝑡

w/o ESS

∑ 𝑃𝐸𝑆𝑆 /𝑃𝑔𝑛 𝑷𝒈,𝒍𝒊𝒎𝒊𝒕

with ESS

(-) (%) (%) (%)

3 2 33.3% 50.0% 50.0%

4 2 50.0% 50.0% 62.5%

5 2 60.0% 50.0% 70.0%

6 2 66.7% 50.0% 75.0%

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690V Main Propulsion Board

ES2

Generator 3333 kVA, 0.9 PF3000 kW, 690 V60 Hz, 900 rpm

G2 G3

Generator 3333 kVA, 0.9 PF3000 kW, 690 V60 Hz, 900 rpm

G4

Generator 3333 kVA, 0.9 PF3000 kW, 690 V60 Hz, 900 rpm

T2

FPP Tunnel Thruster - T12200 KW

690 V1200 rpm

T3

FPP Tunnel Thruster - T22200 KW

690 V1200 rpm

T4

FPP Azimuth Thruster - T53500 KW

690 V1200 rpm

T1

FPP Azimuth Thruster - T43500 KW

690 V1200 rpm

LV Distribution

1000

kVA

690

/ 44

0 V

LV Distribution

1000

kVA

690

/ 44

0 V

LV Distribution

1000

kVA

690

/ 44

0 V

LV Distribution

1000

kVA

690

/ 44

0 V

HRGS HRGS HRGS HRGS

ROV

500

kVA

690

/ 44

0 V

ROV

500

kVA

690

/ 44

0 V

EMG.

250

kVA

690

/ 44

0 V

EMG.

250

kVA

690

/ 44

0 V

ES1

G1

Generator 3333 kVA, 0.9 PF3000 kW, 690 V60 Hz, 900 rpm

Figure 2 –– ESS application to typical OSSV – ESS is assigned to both switchboard sections

In blackout ride-through/recovery mode, ESS operates in stand-alone mode, without paralleled gen-sets as long

as there is reasonable balance between ESS power capability and load demand.

If the load is very low the system can operate with only one gen-set online and ESS is used as back-up in case of

gen-set failure. Then, the bus-tie between two systems can be closed.

Engine low load operation and load ramp-up rate

Load ramp limits prevent engine overloading and stalling by limiting the load at consumers, e.g. thrusters. These

limitations can significantly impact the performance of the power system and are addressed in Table II.

Table II Engine susceptibility to maintenance

Rout cause of

increased maintenance

Mitigation options without ESS Mitigation options with ESS

Low load operation If running less gen-sets, gen-set loading

would be higher.

ESS provides power in case of gen-set fails

to reduce the need for spinning reserve

resulting in less gen-sets to operate more

effectively.

High load ramp-up If running more gen-sets individual ramp-

load will be shared between paralleled

generators.

ESS can provide load support much faster

than the engine. This enables running with

less generators online.

In case of sudden step or load ramp increase, ESS is intended to provide the power until the engines are

available, see Figure 3. The performance will depend on ESS rating and capability. This can improve the

system stability and availability of essential consumers. It can be particularly useful to enable quick force to

thrusters during critical vessel operations.

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Figure 3 – Dynamic engine support mode / smooth engine loading

ESS application for peak shaving mode

ESS power can assist with keeping limits in generators load for limited duration. One possibility is to use ESS in

peak shaving mode when a vessel approaches the harbour and needs quicker responses in manoeuvring, without

necessarily starting additional generators. Figure 4 shows an example of variation in total thruster power

demand calculated for OSV during station keeping.

The available power for peak shaving will be limited if ESS is used in power reserve mode. This is due to ESS

power available in case of prevention or complete loss of available power on generators. Additional ESS power

must be allocated for the power reserve in case of one or more generators cannot be in operation whilst ESS is

peak shaving. If ESS was already used one should consider state of charge (SoC) for blackout support.

Figure 4 – Peak shaving application in station keeping

ESS application for dynamic load levelling e.g. vertical lifting load support operation

For applications requiring lifting and lowering operations, such as cranes or drillship draw-works, it is possible

to configure ESS to absorb the regenerated energy rather than dissipating it in dynamic breaking resistors which

is the norm. Figure 5 shows responses of vertical load control in lowering and lifting operating modes.

The motions of the crane are caused by sinusoidal stochastic vertical motions of the vessel induced by

environmental forces of wind and waves. Vertical motions of the vessel are compensated by the crane which

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tends to keep the constant position of the load by operating electric motors for hoisting. These induction motor

load operations can be approximated by sinusoidal-like (periodic) curve of similar amplitudes.

In order to optimize the required capacity of ESS, it is the best to conduct a mission profile study based on

operating region and load profiles of the vessel.

Figure 5 –– ESS application for vertical lifting load support

ESS application for emission free mode or silent mode

Emission free modes would be very useful to consider when the vessel operates in Emission Control Areas

(ECAs), close to harbour, or entering/leaving harbour. If the shore supply is not available, it would be useful to

consider using other low emission power source in order to reduce air pollution. Battery ESS could be used if

vessel stays in port are short and regular.

Silent mode can be considered very useful in naval applications, when vessel is required to operate without

running engines.

The duration of support would typically vary from just a few minutes in vessel manoeuvring and up to 20-30

minutes in transit for e.g. ferries. For supply vessels, due to their less predictable profile, the duration of the

support could be extended up to one or two hours if the battery can be recharged later at shore. This could enable

emission free operation.

If ESS cannot be recharged in time at shore (plug-in), then the alternative is to run with hybrid power plant. The

engines will run to recharge ESS when consumed power is low and discharge when consumed power is high.

The engines would then be operated close to their optimal point, maximizing energy efficiency. Other alternative

mode for hybrid electrical application would be use ESS to support power when power consumption is low e.g.

in manoeuvring and harbour and recharge by running additional engine online when power is high, e.g. in transit

mode.

ESS SYSTEM INTEGRATION

Design of battery energy storage system

With careful consideration to the ESS capabilities, bearing in mind that the vessel load is predominantly

designed, or requested for UPS support, the converter topology is optimized as shown in Figure 6.

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The main advantage of having input transformer is its galvanic isolation between windings, thus avoidance of

earth fault and common mode voltage propagation. The transformer will also have adequate secondary voltage to

optimise the battery string or ultra-capacitor string voltage and power capability.

Energy storage

Input Transformer

AC breaker

PWM Filter

MainChoke

NetworkBridge

Main Con &Pre-Charge

DC LinkCapacitor

AC-DC Converter

FusesFuses

Main propulsion

grid

Discharging

Charging

Figure 6 - AC-DC ESS converter configuration

Figure 7 shows hybrid system configuration with ESS and motor-generator inverter, concept similar to hybrid

configuration electric vehicles [12]. The main advantage is the input transformer is shared between motor and

ESS which makes it suitable for modifying existing installations. Disadvantage is the energy to the motor must

be supplied also during ESS discharge to the AC grid. If charging is done at lower rates, support to load may not

pose limitations. This concept is more suitable for peak shaving applications. In blackout support mode, the

impact to external system load at AC grid must be considered. The concept can also work without DC-DC

converter, which poses challenges for the control of charge/discharge due to DC-link voltage regulation.

PWM Filter

MainChoke

NetworkBridge

OutputBridge

MotorMain Con &Pre-Charge

InputChoke

M 3 ̴

Input Transformer

AC breaker

Energy storage

Discharging

Charging

DCFuse

OutputBridge

OutputFilter

DCFuse

DC/DC Converter

Figure 7 – Hybrid system configuration consisted of DC-DC Converter and existing VSD converter

Figure 8 shows hybrid converter configuration where more inverters are connected to motor-generators can also

regenerate energy back to local bus. This configuration is suitable for dynamic load levelling applications such as

vertical load lifting operations due to close balancing of energy to the load. It can also limit or completely

eliminate regenerated energy to the main AC propulsion bus.

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PWM Filter

MainChoke

NetworkBridge

Main Con &Pre-Charge

InputChoke

Input Transformer

AC breaker

Main propulsion

grid

Charging/Discharging

OutputBridge

Motor

M 3 ̴

Energy storage

OutputBridge

Motor

M 3 ̴

DCFuse

OutputBridge

OutputFilter

DCFuse

DC/DC Converter

Charging/Discharging limited or eliminated

Figure 8 - Hybrid system configuration for DC-Bus

Effect of ESS voltage on AC-DC converter capability

Most of the ESS used today would typically reduce the voltage with increase in the depth of discharge (DoD)

consequently increasing the ESS and converter current needed to support the required power. If the current is

kept constant the power would drop with the voltage and depth of the discharge. This poses complexity in

specifying ESS.

The diagrams in Figure 9 show the converter capability plots for various ESS voltages and are annotated to show

the active P (MW) and reactive Q (MVar) power at a power factor of 0.9. Separate diagrams are made for each

DC voltage. PQ are varied for each individual transformer voltage ratio factor: 𝐹 = 𝑈𝑇_𝑠𝑒𝑐/𝑈𝐶_𝐴𝐶 which is the

ratio between the transformer secondary voltage applied 𝑈𝑇_𝑠𝑒𝑐 and the converter AC voltage at transformer

secondary 𝑈𝐶_𝐴𝐶 . The diagrams are used to optimise ESS voltage and transformer voltage ratio factor by

selecting PQ limits.

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Figure 9 – Converter capability P/Q diagrams

Figure 10 shows the battery bank string capacity at different discharge rates for Lithium-ion Nickle Metal Cobalt

(NMC) type of batteries. Three different battery voltage string configurations have been compared at maximum

discharge rates. Limiting the battery working voltage within certain State of Charge (SoC) limits is necessary in

order to extend the battery lifetime.

Figure 10 – Battery Characteristic Curves

Optimizing the design allows for maximizing rate of discharge for ESS power block and reducing the string

currents. Figure 11 shows the capabilities of three battery strings of the equivalent energy without capability to

capabilities to support the power, due to voltage drop and converter limitations.

Figure 11 – Duration of discharge support integrated with converters for various types of battery strings

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ESS APPLICATION AND OPERATING COST SAVINGS

This chapter describes the procedure for estimating Operational Expenditure “OPEX” cost savings when using

ESS solution in blackout support mode – enabling use of single gen-set.

The following solutions/modes are compared:

1. System with ESS & optimal use of PMS based on load dependant start/stop tables. Power system in DP

runs with minimum 1 x gen-set, and ESS in backup power reserve mode, supporting power in case of worst

case system failure. If ESS is considered as a redundant source of power [1] then operation with minimum

one gen-set should be allowed. PMS is starting more generators if the power reserve is under 100%, adding

ESS is power reserve calculation.

2. Optimal use of PMS – this is theoretical optimum based on generator load dependant start/stop tables and

considering gen-sets can be started/stopped conveniently. Power system in DP runs with minimum 2 gen-

sets online and PMS is starting more generators if the generator spinning reserve is under 100%.

3. Non-optimal use of power system – gen-sets are not started/stopped as described in 2, due to numerous

constraints, mainly practical reasons and inhibiting gen-set stopping. This situation is considered to typically

occur in the operations. This is defined as theoretically the worst case scenario for the OPEX cost where

assumed all generators are running at all modes except in harbour mode when 1 gen-set is running. In

practice, it is expected the vessel to operate between modes 2 and 3.

DP Capability calculation shows the maximum design criteria when running in DP mode with all thrusters. The

maximum load in DP required by the thrusters is 2,128 kWe.

The main assumptions are:

- Hotel load 500kW in total: 250kW at each bus.

- 4 x diesel generators, each 2250kWe

- Vessel spends 55% of time in DP out of which 25% at 90 deg heading where the thruster load is the

highest and 30% close to zero heading where the thruster load is minimal.

- The operating profile is presented at Figure 12.

Figure 13 shows estimated fuel consumption (tons/year) and gen-set operating hours (hours/year) presented for 3

cases, each for smaller 1100kW and larger 1400kW capacity of ESS. With both ESS fuel consumption is

reduced between 5.4 to 6.2% compared to (case 2.) – Optimally used system.

When compared to non-optimally used system (case 3.) the benefits are very significant –close to 30% in fuel

and 48% in gen-set operating hours.

Figure 12 – Vessel operating profile

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Figure 13 – OPEX savings of ESS in DP and total for all operating modes

Table III Optimizing ESS system size

ESS capacity ESS = 1100kW ESS = 1400kW

Case 1 compared to

cases 2.) and 3.) 2.) OPTIMAL EL-

SYTEM

3.) NON-OPTIMAL

EL SYTEM

2.) OPTIMAL EL-

SYTEM

3.) NON-OPTIMAL

EL SYTEM

Total fuel savings per year in all modes

5.41% 28.71% 6.28% 29.37%

Total operating hour

reduction 23.3% 45.9% 27.2% 48.6%

CONCLUSIONS

This paper describes the design challenges of integrating energy storage solutions and highlights the numerous

advantages of ESS technology for marine application.

ESS capability to provide reductions in the spinning reserve on generators are clearly described and compared.

As summarized in Table III potential fuel cost savings range between 180 tons or 5% to close to 1200 tons or

30%. This is greatly influenced by the vessel operating profile. The potential reduction in generator running

hours is between 23% to close to 50%. Additionally an approximate 150 tons of fuel can be saved if the vessel is

connected to shore when in harbour.

It has generally been demonstrated that ESS can enable general reduction in the operating costs. Initial

calculations carried out by certain operators also show promising results.

The operating risks for the power system can be significantly reduced. This has a great potential to enable easier

introduction of new and more advantaged technology which can improve the efficiency of the power system in

the near future.

Acknowledgement

The authors are grateful for the permission of GE Power Conversion to publish this paper.

Author’s CVs:

Dr Damir Radan, PhD MIEEE holds the role of Senior Application Engineer with GE Power Conversion.

From 1998, he worked as research scientist and lecturer at Dubrovnik University. From 2008 he was enrolled

with Siemens oil & gas offshore Norway as Senior Key Expert. He has broad knowledge in energy solutions. He

made contributions in marine power system design, dynamics & control, energy management and system

protection. In 2008, he obtained a PhD from The Norwegian Technical University-NTNU in the area of marine

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electric power systems and published numerous scientific papers at international conferences. He is a member of

the IEEE.

Mr. Martin Southall, MSc CEng FIET has worked at Ultra-Electronics, Emerson Industrial Automation, TRW

and currently employed at GE Power Conversion as Naval Systems Engineering Manager. He has extensive

Power Systems, Drives, Application and Program Management knowledge and experience. He qualified with a

BEng (Hons) from Staffordshire University in 1995, and achieved a Masters with distinction from Nottingham

University in 2014. He is a Chartered Engineer and was admitted as a Fellow to the IET in 2011. Martin is an

active member of GE’s and Energy Research Partnership (ERP) energy storage steering committees, and has

also lead the delivery of numerous vessel Power Systems.

Dr Makhlouf Benatmane, BSc(Hons) PhD CEng FIMarEST FIET has extensive experience in electrical systems

engineering, in industrial and marine applications. He has been a University lecturer in Power System Design, Electrical

Power Station Design and Power Electronics. He holds a PhD in Electrical Engineering from The University of Nottingham

and a BSc (Hons). He is a Chartered Engineer, Fellow of The Institute of Engineering and Technology, Fellow of The

Institute of Marine Engineering, Science & Technology. He is currently the Fulfilment Leader Marine for GE Power

Conversion.

Martin Butcher, MEng (Hons), CEng, graduated from the University of Leicester with a MEng in Electrical

and Electronic Engineering in September 2000 and joined GE Power Conversion (then ALSTOM Power

Conversion) the same year. Mr Martin Butcher has worked in a number of roles since then and is currently a

controlled title holder within GE, as Principle Engineer, Power Systems. His expertise is primarily in Power

Systems Design and Development (traditional and novel) with a focus on Power System Stability and the

integration of Power Electronic Converters, especially within the Marine Domain. He has worked both within

the commercial and naval marine businesses, from specifying and delivering power systems for platform supply

vessels, to the development, delivery and testing of new power system and products.

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