Stealth Technologies to Reduce the Impact of Wind Turbines on Radar Systems

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COMMERCIAL IN CONFIDENCE COMMERCIAL IN CONFIDENCE

Stealth Technologies to Reduce the

Impact of Wind Turbines on Radar

Systems

Tu Delft, Electromagnetic Waves and Wind Turbines 2018

6-7 December 2018

QINETIQ/18/04489

Vince Savage

+44 7767 478126

vsavage@QinetiQ.com

www.QinetiQ.com/wind-farm-impact-assessment

− Background

− The problem

− Mitigation options

− Stealth wind turbines

− Technologies

− Strengths and weaknesses

− Proven performance

− Case study

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Background

Background: QinetiQ

4

This slide relates to QinetiQ and predecessor companies

.

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• Specifically developed for detection and

discrimination of UAVs

–

Low MDV

–

High Doppler resolution

• comprises 5 independent staring X Band

phased array radars

–

giving 3D coverage over half a hemisphere

• All 5 faces integrated into a single

enclosure

• High track update rate

Background: QinetiQ Obsidian™radar

5 Stealth Wind Turbines | 2018

Wind turbines have the potential to interfere with radar systems. The QinetiQ Radar Impact

Assessment (RIA) team's main aim is to provide high quality, technically sound advice to all

stakeholders in the wind energy industry, to understand and control radar impacts

Background: QinetiQ RIA team

• Where: 26 countries (Europe, USA,

Canada, New Zealand, and South

Africa

• When: 2002 to present

• What: Most radar, navigation aids and

telecommunications…

• Customers: 700+ studies for 250+

Customers (wind farm developers,

radar ANSPs, Government)

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The problem

• Wind turbines can have an unwanted impact on radar systems (and other systems)

• Main impacts are clutter and shadowing

Shadowing (blockage)

_Clutter

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• Clutter example – Germany – average rain data

The problem

Stealth Wind Turbines | 2018 9

• Clutter example – Germany – average rain data + turbines

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Mitigation options

Mitigations

• There are many

options

• Why do we need

to consider

stealth?

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Mitigations

• Radar Mitigations

Mitigations

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Mitigations

• Turbine Mitigations

IN STRICT CONFIDENCE

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Stealth: technologies

• Stealth

Stealth Wind Turbines | 2018

Includes tower &

nacelle shaping.

Not practical to

change shape of

blades

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Stealth: Strengths and Weaknesses

• There are many scattering

mechanisms

• Difficult to reduce RCS of them all

• Shaping

• Good for towers & nacelles

• Not good for blades (cannot

change aerofoil; viewed from

all angles)

• Materials…

[1] https://en.wikipedia.org/wiki/Stealth_ship

Stealthy from here…

…but not from here.

Scattering

mechanisms

Cavity

(chaotic)

Tip

diffraction

Specular

Creeping wave

Multiple

reflections

Edge

diffraction

Travelling

wave

Grating

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Stealth: Strengths and Weaknesses

• What are the

strengths and

weakness of each

option?

• Examples follow –

not exhaustive, just

for illustration

Stealth: Strengths and Weaknesses

• Weight…

Example strength

Example weaknesses

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Stealth: Strengths and Weaknesses

• Weight

• Complexity…

Example strength

Example weaknesses

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Stealth: Strengths and Weaknesses

• Weight

• Complexity

• Maturity…

Example strength

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Stealth: Strengths and Weaknesses

• Weight

• Complexity

• Maturity

• Cost…

Example strength

Example weaknesses

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Stealth: Strengths and Weaknesses

• Weight

• Complexity

• Maturity

• Cost

• Performance…

Example strength

Example weaknesses

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Stealth: Strengths and Weaknesses

• Weight

• Complexity

• Maturity

• Cost

• Performance

• Bandwidth…

Example strength

Example weaknesses

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Stealth: Strengths and Weaknesses

• Weight

• Complexity

• Maturity

• Cost

• Performance

• Bandwidth

• Maintenance…

Example strength

Example weaknesses

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Stealth: Strengths and Weaknesses

• Weight

• Complexity

• Maturity

• Cost

• Performance

• Bandwidth

• Maintenance

• Shadowing…

Example strength

Example weaknesses

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Stealth: Strengths and Weaknesses

• What is practical?

• QinetiQ is aware of

these: perhaps

others?

Practical / proven

Shaping

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Stealth: RCS

Stealth: proven performance

• Data from QinetiQ

database. Maximum

and “average” values

for aircraft, ships,

wind turbines

• Caution: mix of

frequencies,

methods,

polarisation, angles,

elevations ….

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• Conventional

aircraft and ships

• Black dots = wind turbines

• Red dots = aircraft & ships

• Conventional

aircraft and ships

• Stealth aircraft

and ships

• Black dots = wind turbines

• Red dots = aircraft & ships

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• Conventional

aircraft and ships

• Stealth aircraft

and ships

• Conventional

wind turbines

• Black dots = aircraft and ships

• Red dots = wind turbines

• Conventional

aircraft and ships

• Stealth aircraft

and ships

• Conventional

wind turbines

• Stealth wind

turbines

• Black dots = aircraft and ships

• Red dots = wind turbines

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Conventional

aircraft and

ships

Stealth aircraft

and ships

Summary

• Can apply same

technology to

turbines as used for

aircraft and ships

• Similar performance

achieved: reduction,

not “invisible”

• RCS is a distribution,

not a single value

35

Stealth wind

turbines

Conventional

wind turbines

Conventional

aircraft and

ships

Stealth aircraft

and ships

Stealth wind

turbines

Conventional

wind turbines

Summary

• Can apply same

technology to

turbines as used for

aircraft and ships

• Similar performance

achieved: reduction,

not “invisible”

• RCS is a distribution,

not a single value

• Can repower with

larger turbines with

no increase in RCS

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Case Study: Ensemble

Eolien Catalan

Case study: Ensemble Eolien Catalan

• Proposed EDF EN windfarm,

Perpignan, south of France

• Meteo France prescribed

acceptable level of interference

• Project not viable with

conventional turbines

• QinetiQ Stealth Wind Trubine

(SWT) technology used to develop

turbines

• Operational turbines validated with

measurement

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Case study: Ensemble Eolien Catalan

© EDF EN

• World-first stealth wind farm opened in 2016 (EDF EN Ensemble Eolien

Catalan wind farm, France)

• 96MW – 35 stealth turbines

• All turbines use QinetiQ SWT technology to mitigate impact on nearby weather

radar (S band – 2.8GHz)

COMMERCIAL IN CONFIDENCE 40 Stealth Wind Turbines | 2018