[UK-CONTEST] Wind Turbines

[Brian Miller]

Hi all

The level of noise radiated by a wind turbines is dependent on the
type of technology employed. The turbines in the vicinity of ZL6QH are
Siemens 2.3 MW variable speed machines and each one requires a serious
water cooled power converter to match the variable output to the grid.
It appears that it is the power converter (in the base of the turbine
tower structure) that is the main source of the observed HF noise.

Another wind farm to the north of Wellington (at Palmerston North)
uses fixed speed machines. The level of HF noise recorded at this site
was very low and close to the natural background noise level.

I understand that the variable speed turbine technology is relatively
new. It was chosen for the ZL6QH wind farm because it allows the
turbines to deliver higher output operate over a wider range of wind
speeds, and with less acoustic noise.  Unfortunately, this means that
we are also likely to see more of these (noisy) variable speed
machines deployed in the future.

73, Brian ZL1AZE

----- Original Message ----- 
From: "Nick Totterdell" <ntotterdell at riverauto.co.uk>
To: <uk-contest at contesting.com>
Sent: Saturday, February 13, 2010 4:03 AM
Subject: [UK-CONTEST] Wind Turbines


>I have found some useful information relating to tests conducted at 
>the
> ZL6QH Quartz Hill station to determine whether it would be 
> appropriate
> to re-establish the contest station now that the Wind Farm 
> development
> is substantially completed at the site - http://www.zl6qh.com.
>
> I quote...
> "The report concludes that it will not be possible to operate an 
> amateur
> radio HF station in the vicinity of Quartz Hill due to the high 
> level of
> radiated noise interference from the wind turbine infrastructure. At
> 3.73 MHz, the measured level of radiated noise is approximately 50 
> dB
> greater than that sought for weak signal HF amateur radio
> communications. Our analysis of the measurement data suggests that 
> an
> amateur radio station would need to be separated from the nearest
> turbines by a distance of at least several kilometres in order to 
> reduce
> the interference to the desired level."
>
> This confirms my suspicion that despite EMC testing and CE marking, 
> etc.
> the electrical noise emanating from the high power inverter drives 
> (each
> several MW) in the turbine towers is most likely to significantly 
> impair
> HF reception within 1km of the nearest turbine. That the other 
> property
> at a distance of 3km will be significantly affected is less certain.
>
> 73 Nick G4FAL
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