NLD EXPERIENCE ON WINDMILL'S
IMPACT TO RADARS
Regulations and PERSEUS in The Netherlands | Onno van Gent
PERSEUS DEVELOPMENT AT TNO
Defence Research Laboratory established at Waalsdorpervlakte, The Hague
before WW2.
By mid 1980 Defence Research merged into TNO organisation
TNO is a not-for-profit organisation established by law
Since 1995 TNO investigates the effects of wind turbines on Defence radars
and develops assessment methods.
Most recent is PERSEUS, sponsored by Ministry of Defence as well as
Ministry of Infrastructure and Environment.
2 | NLD Experience on Windmill's Impact to Radars
23 November 2016
CONTENT
Dutch regulations
Main features PERSEUS radar performance modelling
Some examples of mitigation measures
Complementary tooling for secondary radar
3 | NLD Experience on Windmill's Impact to Radars
23 November 2016
SITUATION IN THE NETHERLANDS
JANUARY 2016
More than 2000 wind turbines
Eight Air Traffic Control radars
Wier
Leeuwarden
Schiphol
Twenthe
Soesterberg
Nieuw Milligen
Volkel
Woensdrecht
4 | NLD Experience on Windmill's Impact to Radars
23 November 2016
ISSUES OF CONCERN
Densely populated country, with lots of aerospace activity (both civil and
military) and lots of wind.
All flat country.
Small country (approx. 200 x 300 km) in relation to typical radar ranges,
hence many issues for only a handful of radars
Wind farm – radar interaction still a major issue, but solutions available.
5 | NLD Experience on Windmill's Impact to Radars
23 November 2016
6 | NLD Experience on Windmill's Impact to Radars
23 November 2016
ASSESSMENT CRITERIA WIND
TURBINES
Assessment criteria wind turbines restriction area (based on BRA from ICAO):
The tip of the blade (i.e. maximum height of turbine) must not stick though a
cone around a radar position, otherwise it must be assessed by TNO
Cone angle 0.25º starting at primary radar antenna height
Cone diameter 15 km
Between 15 km and 75 km tip of blade not higher than 65 m + primary radar
antenna height, referenced to Mean Sea Level (MSL)
75 km
15 km
0.25°
65 m
Antenna height w.r.t. MSL
Ground level
7 | NLD Experience on Windmill's Impact to Radars
MSL
23 November 2016
CIVIL AND MILITARY COOPERATION
FOR AIR TRAFFIC CONTROL RADARS
Military
Leeuwarden
Leeuwarden
Soesterberg
Twenthe
Volkel
Woensdrecht
ASR-10SS [MinDef]
TAR West
Twenthe
Soesterberg
Civil
TAR West
Volkel
(Schiphol)
Woensdrecht
STAR 2000 [LVNL]
8 | NLD Experience on Windmill's Impact to Radars
23 November 2016
DIFFERENT TARGET HEIGHT CRITERIA
FOR AIR TRAFFIC CONTROL RADARS
Overall coverage: 1000 ft or ≈ 305 m (Purple)
Controlled traffic region (CTR): 500 ft or ≈ 152 m (Blue)
Around airstrip and funnels: 300 ft or ≈ 91 m (Red)
Note: Heights are referenced to ground level
9 | NLD Experience on Windmill's Impact to Radars
23 November 2016
MILITARY CONTROL RADARS (3D)
Medium Power Radar (MPR)
Wier
Wier
Nieuw Milligen (Dutch Mill)
Nieuw Milligen
10 | NLD Experience on Windmill's Impact to Radars
23 November 2016
AVAILABLE RADAR MODELS
Selex ATCR-33K
Thales SMART-L EWC GB
11 | NLD Experience on Windmill's Impact to Radars
Raytheon ASR-10SS
Raytheon ASR-23SS
Thales SMART-S Mk2
Thales STAR 2000
23 November 2016
September 09, 2014
Onno van Gent
PERSEUS Radar Performance Tool
MODELLING WIND
TURBINES
Based on 3D CAD drawings provided
by wind turbines manufacturers:
Enercon
EWT
Gamesa
GE (previously Alstom)
Goldwind
Lagerwey
Nordex
Senvion (previously REpower)
Siemens
Vestas
12 | NLD Experience on Windmill's Impact to Radars
23 November 2016
PERSEUS TOOLKIT
Program for the Evaluation
of Radar Systems in an Extended Urban Setting
Compliance with existing guidelines
ICAO EUR DOC 015 (2009)
CAA CAP 764 (2010)
Eurocontrol Guideline (2014)
Wind turbine static & moving parts
Desensitization Overhead: CFAR processing & pulse compression
Shadow Effect
Multiple-radar data fusion, gap fillers
Line-of-sight and diffraction (TERPEM) based on SRTM terrain height database
Volumetric assessment
Versatile radar modelling (based on TNO’s CARPET, with 600+ licenses sold worldwide)
13 | NLD Experience on Windmill's Impact to Radars
23 November 2016
PERSEUS RADAR PERFORMANCE
CALCULATIONS
Single scan detection probability (Pd) of a target (aircraft) having a radar
cross section (RCS) 2 m2 at a target height of 300, 500 and 1000 ft.
Example: MASS radar Leeuwarden,
Target height 1000 ft
Pd
100%
√
Coverage at 1000 ft
Approx. 80 km (45 NM)
90%
Position radar
Leeuwarden
X
Blocking (shadow) caused
by tall buildings Leeuwarden
14 | NLD Experience on Windmill's Impact to Radars
80%
<70%
23 November 2016
PERSEUS RADAR COVERAGE DIAGRAM
(1000 FT) INCLUDING WIND TURBINE
INTERFERENCE EFFECTS
Pd
100%
90%
Time sidelobes
(pulse compression)
Loss maximum
coverage due to
shadow
Cumulative
interaction
80%
Desensitisation
overhead (CFAR)
<70%
15 | NLD Experience on Windmill's Impact to Radars
Radar
position
23 November 2016
16 | NLD Experience on Windmill's Impact to Radars
23 November 2016
MITIGATION MEASURES
Wind turbine adaptations:
Smaller design
Radar angle avoidance
Radar absorbing (blade) materials or coatings
Radar system adaptations:
Radar fusion of data from multiple radars, e.g. ATM suRveillance Tracker
And Server (ARTES) of EUROCONTROL combined with additional radars
Realisation of additional radars including Gap-filling radars
3D radars instead of 2D radars
Processing improvements within the radar receiver
17 | NLD Experience on Windmill's Impact to Radars
23 November 2016
DATA FUSION OF MULTIPLE RADARS IN
SAME RADAR NETWORK
XX XX
X XXXX
XXX X
X X X XXXXX
X XXXXXX
X XX X
X XXXXX
XX X
XX XXX
X
X
X
Flight height 1000 ft
Radar A
18 | NLD Experience on Windmill's Impact to Radars
23 November 2016
DATA FUSION OF MULTIPLE RADARS IN
SAME RADAR NETWORK
The wind turbines do not have
an effect on radar B due to the
fact that they are beyond the horizon.
Radar B provides detection
above wind turbines
X
X
X
X XXXXX
XX X
XX XXX
Radar A
19 | NLD Experience on Windmill's Impact to Radars
Flight height 1000 ft
Radar B
23 November 2016
DATA FUSION OF MULTIPLE RADARS IN
SAME RADAR NETWORK
The wind turbines do not have
an effect on radar B due to the
fact that they are beyond the horizon.
Radar B provides detection
above wind turbines
X
X
X
X XXXXX
XX X
XX XXX
Radar A
20 | NLD Experience on Windmill's Impact to Radars
Flight height 1000 ft
Radar B
23 November 2016
CASE: WINDFARM 96 TURBINES.
BENEFITS OF AN ADDITIONAL RADAR AT DEN HELDER
Shadow
21 | NLD Experience on Windmill's Impact to Radars
Desentisation Additional
overhead
radar
23 November 2016
3D RADAR OPERATION
Only interference in the
lower beams.
Higher beams without interference
can still detect targets
X
XX
Loss of maximum range
Due to shadow effects
Wind turbines
Flight height 1000 ft
XXX
X XXXX
3D Radar
22 | NLD Experience on Windmill's Impact to Radars
23 November 2016
3D RADAR OPERATION
X
XX
XX
XXX
XXX
X XXX
X XXXX
Loss of maximum range
Due to shadow effects
Wind turbines
Flight height 1000 ft
3D Radar
23 | NLD Experience on Windmill's Impact to Radars
23 November 2016
3D RADAR OPERATION
Only interference in the
lower beams.
Higher beams without interference
can still detect targets
X
X
Flight height 1000 ft
XXX
X XXXX
3D Radar
24 | NLD Experience on Windmill's Impact to Radars
23 November 2016
PARALLEL PROCESSED BEAMS
The high beam, normally only used
up to typically 15 km can now
be used for greater distances for
higher flying targets.
High beam provides
non-interfered detection
above wind turbines
XX XX
X XXXX
XXX X
X X X XXXXX
X XXXXXX
X XX X
X XXXXX
XX X
XX XXX
X
X
X
Flight height 1000 ft
Radar
25 | NLD Experience on Windmill's Impact to Radars
23 November 2016
RADAR PROCESSING IMPROVEMENTS
Standard operation
Target at 1000 ft
26 | NLD Experience on Windmill's Impact to Radars
Upgrade Constant
False Alarm Rate
(CFAR) thresholding
Target at 1000 ft
Parallel processing
high-low beams
Target at 4000 ft
23 November 2016
IN-FILL OR GAP-FILLING RADARS
Aveillant, Holografic radar
SRC, LSTAR
C-Speed, Lightwave radar
Terma, Scanter 4002
Intersoft Electronics
…….
27 | NLD Experience on Windmill's Impact to Radars
23 November 2016
28 | NLD Experience on Windmill's Impact to Radars
23 November 2016
IMPACT ON SECONDARY RADAR
Civil application radar, used for air traffic control
Cooperative system: dependent on transponder on board of the aircraft
SSR provides additional information (ID, altitude, etc.)
In case of monopulse SSR (MSSR), system also capable of accurate
estimation of target bearing (typical within ~0.05°)
Secondary Surveillance Radar (SSR)
Primary Surveillance Radar (PSR)
29 | NLD Experience on Windmill's Impact to Radars
23 November 2016
BEARING ERROR
Wind turbines, positioned between target and MSSR antenna can disturb the
transponder signal, introducing an error in the bearing estimate
Included in PERSEUS toolkit
30 | NLD Experience on Windmill's Impact to Radars
23 November 2016
VALIDATION OF SIMULATED RESULTS
FOR SINGLE OBSTACLE
Recorded Real track
31 | NLD Experience on Windmill's Impact to Radars
Simulated track
23 November 2016
MULTIPLE WIND TURBINES
Line-of-sight analysis
Digital elevation model (DEM)
Off Boresight Error (OBE)
calculation
Absolute OBE per azimuth
sector
32 | NLD Experience on Windmill's Impact to Radars
23 November 2016
SUMMARY
Wind turbines cause interference on radars.
The Netherlands developed a successful assessment and mitigation scheme
PERSEUS toolkit has a central role
With conflicting interest between government & industry TNO is often
involved as an independent intermediate.
Involved in international studies for customers in Curaçao, Belgium, United
Kingdom and Australia.
33 | NLD Experience on Windmill's Impact to Radars
23 November 2016
FOR MORE INFORMATION
Point of Contact:
Onno van Gent
Telephone: +31 (0)88 86 64 025
Email: [email protected]
See also:
TNO Website:
http://www.tno.nl/perseus-EN
TNO Time magazine:
https://time.tno.nl/en/articles/whyradars-and-wind-turbines-do-nothave-to-cause-problems-for-oneanother/
34 | NLD Experience on Windmill's Impact to Radars
23 November 2016
THANK YOU FOR YOUR ATTENTION