Transcript Document
Netherlands Institute for Radio Astronomy
Wind turbines and LOFAR
Hans van der Marel
ASTRON
Wind Turbine meeting, Chalmers
ASTRON is part of the Netherlands Organisation for Scientific Research (NWO)
1
LOFAR
Low Frequency Array
10 - 90 MHz (LBA)
110 - 250 MHz (HBA)
Arranged in stations
Station connected with
fibres
Station correlation
Central correlator
(Groningen)
2
LOFAR locations
Core
Remote
stations
International
stations
3
LOFAR core and environment
Large receiving
surface
Short baselines
Susceptible to
interference
Radio quiet zone
coordination zone
of ~ 6 km
Wind turbines!
4
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
5
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
6
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))
7
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
8
Spectrum Measurements (1)
9
Spectrum measurements (2)
10
Amplitude measurements on FM
transmitter frequency
11
Emission measurements (inside wind
turbine near electronics cabinet)
12
Emission measurements (2)
13
Emission measurements (3)
14
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
15