Date: 7-May-14
Mitigation techniques for wind turbine
induced primary radar performance
degradation.
Dr. Bram Faes
bram.faes@intersoft-electronics.com
Intersoft Electronics
Intersoft Electronics
Since 1983
Olen - Belgium
Original focus on radar test equipment (RASS)
Recent years: Processing: NGSP
slide 3
IE Around the World
IE Windfarm Mitigation Approach
No single solution which works in all cases
IE has a range of mitigation techniques that meet almost
all situations
1. Gap filler – Networked solution
2. Modify existing sensor:
- True 3D height extraction enhanced false plot filtering
- Vertical Clutter Cancellation – Doppler independent
- Next Generation signal Processing
3. New windfarm ‘resistant’ sensors
- ASR-C3, -C4, -M, -NG
IE have extensive modelling and visualisation capabilities
and experience
slide 5
Gap filler sensor
Short pulse - High resolution (range – azimuth)
RAG (Range Azimuth Gating) the turbine
High resolution to limit RAG areas
Stand alone
Networked solution
Gap filler sensor
ASR-C3
Tactical Airfield Surveillance Radar
Gap filler
Short range Military/Civil airport/Airfield Surveillance Radar
Typically 20-50 Nm instrumented range S band 3D PSR radar
Typically 1 – 2 KW PSR transmitter Based on NGSP and NGTx
slide 7
NGSP
Wind turbine mitigation
No single solution
NGSP: combination of techniques to reduce clutter
NGSP
High range resolution
Range and azimuth beam profiling applied in plot extraction Mathematical sidelobe minimization
Improves target accuracy
Resolve between adjacent turbines and/or targets Rejects returns entering sidelobes
High resolution MTD
16 channel MTD processing
slide 9
NGSP
Range azimuth gating
3D height extraction
Advanced plot filtering
Height, RCS, ground speed, etc. Target classification
Scan to scan correlation (Non-track-coast based)
Optimized filtering of unwanted returns (Turbines) Enhanced tracking of wanted returns (Aircraft)
NGSP
Automatic track initiation areas
Inhibits initiation of tracks from within defined wind farm areas
Vertical Clutter Cancellation (VCC)
Only available in 3D NGSP radars
Doppler independent Cancels wind farm clutter
slide 11
VCC
Adaptive beam elevation notch
Sharp notch
Improving vertical roll-off
Create null on the elevation of the clutter
Optimal performance from
㼼
10 km (depending on
turbine size)
Range/Azimuth cell based
Only enabled in problematic areas
Independent of Doppler
slide 13
NGSP VCC windfarm cancellation
• Recordings made from a two-elevation beam Radar in Northern Europe
• Recordings made can be visualized using the IE SPS tool to permit "real world“ wind-turbine mitigation performance to be measured
• The turbines in these recordings are of the order of 80m tower height and
located at ranges of typically 7-13nm from the Radar
NGSP VCC windfarm cancellation
Log Video – VCC Disabled
• The top panel: range vs. amplitude plot of the raw data from the wind turbines.
• The Yellow vertical cursor is set to the peak range of one of the turbines
• Lower right panel: azimuth vs amplitude of the selected range. Turbine return.
• The peak of the return has amplitudes in excess of 70dB.
Log Video – VCC Enabled
• The top panel: range vs. amplitude plot of the raw data from the wind turbines.
• White curve = No VCC • Red curve = VCC
• Lower right panel: azimuth vs amplitude of the selected range. Turbine return with VCC • Peak return of approx. 45 dB
slide 15
NGSP VCC, MF and Doppler Processing
Raw returns (Log Video) Post Pulse Compression PC gain 18dB VCC and median filter processes disabled Doppler Bin 0 Doppler gain 13dB Raw returns (Log Video) Post Pulse Compression PC gain 18dB VCC and median filter processes enabled Doppler Bin 0 Doppler gain 13dB
Upgraded 743D at Parnis Greece
• Recordings made can be visualized using the IE SPS tool to permit "real world“ wind-turbine mitigation performance to be measured
slide 17
NGSP Mitigation in Upgraded 743D
Log Video azimuth vs range vs amplitude of the turbine
returns
Post PC and VCC azimuth vs range vs amplitude of the turbine
returns
Post Median Filtering azimuth vs range vs amplitude
of the turbine returns
NGSP upgrade references
S723 Semmerzake
S743 Greece (Namsa – NSPA)
ASR-8 Estionia
ASR-8 FAA – Telephonics (> 30 systems)
ASR-NG Henshold
TA-10 Kleine brogel
SRE-M6 Saint-Hubert
ASR-C3 Brussels
slide 19
New windfarm ‘resistant’ Sensors
ASR-C4, ASR-M
Airfield/Airport Surveillance Radar
Medium range Military/Civil airport/Airfield Surveillance Radar
Typically 60-80 Nm instrumented range S band 3D PSR radar
MSSR
Typically 1 – 8 KW PSR transmitter Based on NGSP and NGTx
Modular design/Configurations Single or dual channel system Integrated IFF or LVA
Summary
IE has advanced mitigation capabilities
Range of solutions to fit all cases
IE wind farm mitigation capabilities have been demonstrated
Demonstrations through analysis and modelling Operational systems
Key mitigation techniques are
VCC
Median filter RAG
slide 21
Summary
VCC has been demonstrated to provide an effective, Doppler independent, turbine clutter cancelation factor of up to 30 dB.
MTD can provide a turbine/target Doppler dependent, turbine clutter cancelation up to 40 dB
Future additional clutter compensation techniques (VCC adaptions)
Enhanced close range clutter cancellation
