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Wind farm meeting 27 April 2010, Goteborg (SE)

Wind farm meeting 27 April 2010, Goteborg (SE) Measurements of primary radiation at a wind farm close to the Sardinia Radio Telescope R. Ambrosini (IRA), P. Bolli (OAC), C. Bortolotti (IRA), F. Gaudiomonte (OAC), F. Messina (OAC), M. Roma (IRA). Agenda.

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Wind farm meeting 27 April 2010, Goteborg (SE)

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  1. Wind farm meeting 27 April 2010, Goteborg (SE) Measurements of primary radiation at a wind farm close to the Sardinia Radio Telescope R. Ambrosini (IRA), P. Bolli (OAC), C. Bortolotti (IRA), F. Gaudiomonte (OAC), F. Messina (OAC), M. Roma (IRA)

  2. Agenda • The Sardinia Radio Telescope; • The RFI mobile station at SRT; • Characteristics of the wind farm under test; • Measurements: • Spectrum in P, L and S bands from power station and from each single turbine; • Wide and narrow band emission; • Dependence of the RFI intensity vs the distance.

  3. SRT TechnicalSpecifications • Fully steerable radio telescope for: Radio astronomy , Geodynamical studies, Deep Space Network, Single dish and VLBI • 0.3-100 GHz continuous frequency coverage • 64 m diameter primary mirror; 7.9 m diameter secondary mirror • Gregorian configuration with Shaped Surfaces • Active Surface: Primary mirror with 1116 actuators • a) Compensate gravitational and thermal deformations • b) Convert Shaped surface of the primary to a Parabolic • surface for primary focus operation • Six focal positions (up to 20 receivers): • Primary, Gregorian, Four Beam Wave Guide • Primary surface accuracy:  150 um RMS • Pointing accuracy (RMS): 2 ÷ 5arcsec

  4. Featuresof SRT site The SRT site is located 35 Km North of Cagliari (700 m asl). Latitude: 39d 29m 50s N Longitude: 9d 14m 40s E The site is well shielded by mountains around the radio telescope. The area is far away from populated centers (small villages at > than 5 Km).

  5. Wind farm closeto SRT

  6. SRT Mobile RFI station

  7. Characteristics

  8. Effectsproducedbywind farm • Microwave link for telemetry and remote control; • Emissions from generators and transformers; • Sparks and corona from power lines and insulators; Primary radiation Secondary radiation Reflection of radio links; Instability of background Modulation of the near field background signal of the antenna by its periodically varying electrical characteristic

  9. Characteristicsof the wind farm

  10. Electricalscheme

  11. RFI campaigns

  12. Survey at the wind farm AZC 40° Distance @ 3.5 Km; session #3

  13. Pointing measurement Pol. V Pol. H -62.6 dBm AZC 40° yellow AZC 40°+90° blue AZC 40°-90° purple

  14. Wide-bandmeasurement Max hold Single view Blue : Pol. V Yellow: Pol. H Distance @ 500 m; session #3

  15. Zero-spanmeasurement Distance @ 1 Km; session #3

  16. Emission in P-band 20 Jan. (rainy) 19 Jan. (sunny) Distance @ 3.5 Km; session #1,2

  17. Emission at largedistance n. 9 @ 7 Km

  18. RFI campaign at a wind farm Powerintensitydrops in line-of-sight at -100 dBm at 85 Km!

  19. Monitoring in L and S bands 21 cm line S band Below the sensitivity? Distance @ 1 Km; session #3

  20. Other notes • Narrow band analysis in P and L-band (to monitor intentional control signal) did not show any signals coming from the wind park…. • We didn’t measure wide-band emission from the single turbine….. • …..with the sensitivity of • our RF equipment!

  21. Conclusions • Very high power wide band RFIs coming from power station have been received (especially in P-band, but also in L-band). • Those effects are probably due to sparks phenomena which are worst in dry condition. • The spectral distribution and the polarization of the RFI emission are variable (depending on the position); • More accurate measurements of emission from single turbine and investigations of secondary effects are planned.

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