Netherlands Institute for Radio Astronomy

1 ASTRON is part of the Netherlands Organisation for Scientific Research (NWO)

Wind turbines and LOFAR

Hans van der MarelASTRONWind Turbine meeting, Chalmers

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LOFAR

Low Frequency Array

10 - 90 MHz (LBA)

110 - 250 MHz (HBA)

Arranged in stations

Station connected with fibres

Station correlation

Central correlator (Groningen)

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LOFAR locations

Core

Remote stations

International stations

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LOFAR core and environment

Large receiving surface

Short baselines

Susceptible to interference

Radio quiet zone coordination zone of ~ 6 km

Wind turbines!

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Wind turbines in Drenthe

Up to 200 MW in 2020

At least 3 MW per wind turbine

Clusters of at least 5 wind turbines

No wind turbines in LOFAR zone 1 (radio quiet zone)

Only wind turbines in LOFAR zone 2 (coordination zone) if they do not impede the LOFAR project

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Windfarm ‘Hondtocht’

LOFAR monitoring survey in October 2006

Local authority: Dronten (Flevoland)

Wind turbine: Vestas - V66 - 1,75 MW

Number of wind turbines: 8

Installed capacity: 14,75 MW

Rotor axis height: 67 metres

Rotor diameter:66 metres

Measurements by:Mark Bentum and Harm-Jan Stiepel

Processing by: Rob Millenaar and Albert-Jan Boonstra

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Measurement set-up

R&S ESMB monitoring receiver (9 kHz - 3 GHz)

R&S HE010 active antenna (9 kHz - 80 MHz)

VULP 9118G passive antenna (35 - 1500 MHz)

Miteq 10 - 1000 MHz amplifier (18 dB)

Rotors for azimuth and polarisation

(R&S FSP spectrum analyzer (9 kHz - 3 GHz))

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Measurements

Scatter measurements of FM transmitters

Spectrum measurements wind turbine ON / OFF

5 - 80 MHz

30 - 1000 MHz

‘Standard’ LOFAR monitoring measurements

Spectrum analyzer measurements

Amplitude

Emission

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Spectrum Measurements (1)

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Spectrum measurements (2)

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Amplitude measurements on FM transmitter frequency

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Emission measurements (inside wind turbine near electronics cabinet)

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Emission measurements (2)

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Emission measurements (3)

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Conclusions

Electronics is potential source of emission

Partly shielded by wind turbine structure

Might be different for other wind turbines

Amplitude modulation due to variable reflections

For LOFAR frequencies AM on already distorted channels due to dispersion

More investigations needed:

Emission and reflections of bigger wind turbines and other types

Dispersion and reflections at higher frequencies