Protecting onboard DC power systems against fault conditions with solid-state DC breaker technology

Peter van den Berg & Aniket Sarode

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Introduction

Peter van den Berg

• Technical consultant

• KWx

Aniket Sarode

• Technical Sales Specialist

• KWx

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Growth in world economy is expected to double over the next 20 years

This gives rise to global energy needs

The energy landscape

020406080

100120140160180200220240260280300320340360380400

2000 2010 2020 2030 2040 2050

Projections

Rest of the world

South Africa

Russia

Indonesia

Brazil

EU-OECD

US

India

China

Gross Domestic Product (Trillions)

0

5

10

15

20

25

1965 1975 1985 1995 2005 2015 2025 2035

Bill

ion

to

e Energy Consumption by region

OECD China India Other non OECD Asia Africa Other

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Use of energy in transport sector is also on a rise

Transport accounts for 27% of global energy use

Which resulted into significant number of harmful emissions so far

0

50

100

150

200

250

1980 1990 2000 2010 2020 2030 2040 2050

World final energy demand by sectors EJ/yr

Non Energy

Other

Manufacturing

Building

Transport

0

5000

10000

15000

20000

25000

30000

35000

1990 2005 2006 2010 2015 2025 2030

Million Metric Tonnes CO2

Brazil

Africa

Middle East

India

China

Australia/New Zealand

South Korea

Japan

OECD Europe

Mexico

Canada

US

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Shipping industry has its own share

• More than three percent of global carbon dioxide emissions can be attributed to ocean-going ships. This is an amount comparable to major carbon-emitting countries-(World Economic Forum – 2018)

• If global shipping were a country, it would be the sixth largest producer of greenhouse gas emissions.

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1 gigatonne CO2 emission per year5 million barrel fuel use per day10-15% of Global NOx4-9% of Global SOx

Marine applications result in:

According to the IMO GHG assessment, Marine carbon emission is expected to grow by 250-350% from 2007 to 2050 due to global trade expansion.

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Shipping

27% of all the energy we consume goes towards

transport

There’s a clear problem…

Replacing current use + keep up with growth

Our consumption of fossil fuels is still growing and total energy

consumption is expected to grow another 48% before 2040

Climate change

CO2 emissions are bringing our planet to abrupt and irreversible

danger

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Shipping

Smart (DC) energy management and protection

system onboard.

… and a clear solution

Replacing current use + keep up with growth

Smart shipping electrification and hybrid ships

Climate change

Renewable Energy + Smart grids are promising

prospects

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Electricity is already bound to become the

main energy carrier

0

50

100

150

200

250

300

350

400

450

1980 1990 2000 2010 2020 2030 2040 2050

Ej/Y

r

Forecast world final energy demand by energy carrier

Electricity Oil Natural gas Coal Biomass Direct heat

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Solar PV will be competitive with wholesale prices across the whole of

Europe by 2023

0

20

40

60

80

100

120

2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030

€cents/kWp

Minimum PV generation cost Maximum PV generation cost

Minimum wholesale price in Europe Maximum wholesale price in Europe

Transition phase throughout Europe until 2023.

Source:Becquerel Institute

Comparison of PV generation costs range in EU (2016-2030) and medium scenario for Wholesale electricity price development

Power Electronics technology is also steadily moving ahead

• Advancements in the power electronics technology steered the development of ships in the direction of hybrid AC/DC and full DC power systems.

• As the energy sources available to the maritime industry evolve, so must the power platform enabling them.

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DC grids are widely used for marine applications.

• DC grids provide power stability, fuel flexibility and energy storage benefits and enables ship integrators to achieve protection selectivity.

• To the ship owner this provides more flexible and competitive vessel, but it poses a challenge for ship protection and safety.

• Fast fault current interruption is very important for ships at sea.

• This calls for innovation in shipping.

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Ind

ust

ry C

o o

per

atio

n

Industry Innovation

shipping

Social enterprises

IT

Chemicals

fashion

Shipping innovation is complicated

• Lack of information sharing.

• Lack of investment due to low margin business.

• High risk- difficult to tackle issues at sea.

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Advantages hybrid / electric vessels versus conventional design

• Power electronics in distribution (own DC micro grid)

• Highly controllable voltage sources

• Power stability

• Power Quality

• Easy synchronisation

• Easy integration with Energy Storage Systems

• This will lead to:

• Reduced fuel consumption

• Reduced emmissions

• Less maintenance

• Less components

• Safety

• Prospective short circuit currents up to 300kAWe see very high short circuit currents in large DC systems.

• High dI/dt (up to 1000A / μs)Systems are designed with low inductances which lead to rapid current rises during faults

• Selectivity and complex safety scenarios due to new system topologies.By choosing the correct type and positioning of protection devices at distribution protection levels, protection selectivity is achieved.

• Market demand and availability

• Lack of available (dedicated) DC componentsAC -> DC components like fuses but also a restricted portfolio due to Voltage levels higher than1000V.

• Lack of up-to-date guidelines and standardsDifferent organizations (NEN, IEC, IASC, IEEE) are in the process of updating the standards based on market development. KWx is participating in different norm committees.

Challenges in DC micro grids

Motivation for development• In 2014 we recognized a clear tendency towards increased use of DC onboard

vessels. • System integrators were struggling with proper protection of DC power grids.• 2015: Brainstorm session with a group of shipbuilders, system integrators and

manufacturers of PE components.• In short: what specifications are required for the development of a DC breaker

switch to protect DC systems against fault conditions on board vessels?

Research and development

• Based on the brainstorm session and other market input we started with theresearch phase

• partnership for product development with Astrol Electronic AG was signed

• During 4 years a lot of research, development and testing was done.

• Due to the clear focus on developing sustainable systems and the application of renewable energy sources, preference is given to DC over AC.

• International Maritime Organization and Government goalsNew rules are introduced to reduce and eventually ban the use of fossil fuels.

• Did we make the right decision?Looking at the current need and the number of planned and executed projects, we canonly say that we have chosen the right direction 7 years ago.

Current situation

The result of our efforts: The Astrol DC breaker Switch...

Important features

• Primary function• Ultra-fast interruption and clearing time.

The primary and most important function of solid-state DC breaker switch technology is the ultra-fast interruption of high powers, thereby preventing dramatic consequences of short circuit situations.

• Additional benefits• Enabling the design of sustainable and future-proof DC

systemsIt allows the integration of modern energy sources and enables the design of efficient topologies such as closed bus tie systems and zone protection.

• System-independent solutionIt’s considered as a discrete component and therefore system-independent. It enables easy integration into new and existing systems.

• Type approvalIt was also apparent, although not necessary according to the rules, that it should have a type-approval, to simplifiythe process of getting a complete system certified.

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Semiconductors in solid-state switches

Press-pack IGBTPress-pack diode

• IGBT module• Speed• Safe fail-to-open mode (in extreme short-circuit operation)• Isolated housing (for easy liquid cooling)

MOV

• Diode module

• Over voltage protection

Schematics

Schematics

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Example 3600A - 1000V - 1μH - @ 10μs

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Short circuit handling

Total system inductance 1uH:-Trace1 = Breaker Feedback (low = open, high = closed)-Trace3 = Breaker Terminal Voltage-Trace4 = Breaker CurrentDetection Time = 4us, Breaking Time = ~7us

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Enabling advanced system designs

A DC micro grid can be made more reliable and efficient, by using multiple buses for redundancy. Multiple busesprovide multiple configuration options for supplying power to the load. It also offers the possibility to achieve zone protection. This also include (meshed) ring-bus based DC microgrid architectures.

The only way to protect these kind of topologies is to create a meshed security layer by connecting all solid-state DC breaker switches.

To ensure selectivity, it is possible to increase the protection thresholds, to avoid tripping in healthy zones during external faults, or to switch off specific DC breakers based on fault direction and/or location.

DCB #1 DCB #2 DCB #3 DCB #4 DCB #5

Product range3 mechanical versions of 1kV DC breaker switches

Higher current and/or voltages on request

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Interface to host system

• Ethernet based protocols

• MODBUS TCP/IP

• CAN

• Profinet

• …

• Optical Interface

• Glass or POF for ON-OFF and Status Feedback

• Power Connection

• Cables (0.5kA & 1.25kA)

• Bus Bar (1.25kA, 3kA, ...)

Ease of Integration

Our DC breakers play a crucial role

The DC breaker switch is a system-independent solution with a modular design and therefore easily integrated into

new and existing systems.

Safety

Ultra-fast switch-off times (μs).Solid-state DC breaker switches prevent arcing in case of short circuit situations

Cost efficient and green solution

smarter solutions leading to fuel savings, lower maintenance costs and a reduction of the environmental

footprint.

Innovative closed bus solution

A closed bus system is a more complex integrated system, which is demanding to build, verify and operate safely. Solid

state switching technology enables system integrators to design smarter solutions with equivalent safety

Increasing market size Maximum vessel uptime

Our switch ensures maximum safety onboard , while reducing the total cost of ownership by preventing

losses from system down-time and failure

DC breaker market Size is expected to grow to USD 17.85 Billion By 2027 At CAGR Of 11.10%

Thank you

Astrol Electronic AG

Ahornweg 14

CH-5504 Ohtmarsingen

Switzerland

+41 (0)56 485 60 20

info@astrol.ch

KWx B.V. (Nederland)

Aston Martinlaan 41

3261 NB Oud-Beijerland

Nederlands

+31 (0)186 – 633 600

info@kwx.nl

Peter van den BergTechnical Consultant

Aniket SarodeTechnical Sales Specialist