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Radar Impact Assessment UK Offshore Wind 2003, 26-27 March 2003. Dr John G Gallagher. Contents. 1 The radar impact 2 Approach 3 Computer model 4 Radar trials 5 Validation. The radar impact. Section 1. The problem. Important for Offshore and On-shore wind farms
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Radar Impact AssessmentUK Offshore Wind 2003, 26-27 March 2003 Dr John G Gallagher
Contents 1 The radar impact 2 Approach 3 Computer model 4 Radar trials 5 Validation
The radar impact Section 1
The problem • Important for Offshore and On-shore wind farms • radar used for maritime navigation and safety • land-based radar • ship-based radar • Air Traffic Control radar • Associated electromagnetic issues • Communications (HF, VHF to microwave) • GPS, DGPS • AIS • Radar beacons (racons) • SSR
The radar problem • Safety at sea and airspace safety • Wind turbine interaction with radar affects • Marine radar both land-based and ship-based radar • Air Traffic Control primary radar and SSR • by • giving rise to false targets on radar • obscuration of wanted targets as a result of radar shadows cast behind turbines • corrupts information on the radar waveform
Approach Section 2
Need • There is a need to understand the operational impact of siting wind turbines near radar and other electromagnetic systems • Radar cross-section (measure of energy scattered) • propagation of radar energy • Who are the main stakeholders and what systems do they operate that may be affected by the wind farm • Determine the key interaction parameters that affect the radar and other electromagnetic systems
Approach • DTI Renewable Energy Programme funded model • Generate detailed electromagnetic scattering predictions of wind turbines • In the case of radar systems configure computer model to simulate the effects of wind turbines on radar • Carry out a trial to collect measured data of a turbines and relate it to the turbine state (pitch, yaw, RPM) • Validate computer model using the measured data
Computer model Section 3
Computer model • Modular components allow configuration for offshore and on-shore environments • Transmission from radar • Propagation over terrain to turbines • Complex scattering from turbines • Return of complex echo to radar • Radar processing • target discrimination in range and bearing • (MTI / Threshold Etc.)
Radar cross-section predictions • CAD models made from data supplied from manufacturers • Meshed appropriately for input to RCS code
Radar cross-section predictions • Results show RCS of complete turbine to be generally between 10dbsm -30dBsm (10m2 - 1000m2)
Computer model • Display • Takes time history data files from prediction files and displays them on the PPI display • The computation is run on QinetiQ high performance computer facility
Radar Trial Section 4
Radar Trials • The QinetiQ MPR instrumentation radar measures the radar signature of a wind turbine
Measured RCS of wind turbine RCS (dBsm) • 23 RPM • 40° Yaw Time (secs)
Validation Section 5
Validation • Simulation • CAD model of turbine • Propagate electromagnetic wave • Predicted wind turbine RCS; • Radar signal process model through to PPI display • Measurement • Gathered wind turbine truth data • Measured the RCS of a wind turbine • Collected video of a real PPI display showing a wind farm • Compare measured data with the predicted data for validation
Validation • The RCS predictions reproduce the peaks and basic trend of the measurement data; • The simulation agrees well with the recorded PPI display for single turbine configurations; • The model is shown to be between 93% and 98% accurate for several configurations of a single turbine.