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Our data demonstrates that signal degradation for radio signals and the

interference to the Airport Surveillance Radar (ASR) presented by the single wind turbine

is minimal. The impact in radio communications is minimal. However, HF and VHF

radios may be susceptible to Frequency Fading, Time Dependant Fading, Doppler

Spread, Depolarization, Signal Reflection and Signal Refraction and may encounter

interference when using the frequencies listed in Table 5. Frequencies half way between

consecutive harmonics is expected to cause the least amount of interference.

Although, the ASR is susceptible to interference caused by the Wind Turbine,

fortunately due to its location, it is partially masked by the terrain and the distance places

the turbine blades outside the ASR angle zone of interest.

II.

TASKS

A.

PRECONSTRUCTION SURVEY

1.

Objective

Determine if measurable energy is being emanated in the form of RF noise, using

wind turbines at other sites as examples (Sasarita, 2013, p. 2-1). “If RF noise is detected,

identify frequency and dependencies, such as the wind speeds, affect on frequency,

magnitude, or other noise characteristics” (p. 2-1).

This task allowed the gathering of information required to write the wind turbine

test plan.

2.

Criteria

RF noise measures are relative to the noise floor in the vicinity of the system

under test (SUT) (wind turbine) (Sasarita, 2013, p. 2-1).

Measurable RF noise is defined as any clearly defined peak of 6 decibels (dB) or

more above the noise floor at the frequency of interest, measured at the edge of the safety

zone of the SUT (Sasarita, 2013, p. 2-1). The safety zone, for this task, is defined as a

circle around the base of the wind turbine with a radius, which is the greater of 100 feet

or one and one-half times the diameter of the turbine blades (194 feet) (p. 2-1). Therefore,

for the wind turbine used, the safety radius is 291 feet (p. 2-1).

a.

Procedures

Prior to construction of the Nordic Windpower N1000 turbine at Ft. Huachuca,

AZ, another wind turbine site was visited and spectrum monitoring was conducted to

scope the magnitude of potentially interfering harmful emanations from the turbine,

transformer, and power lines.

Figure 4. Warren AFB, WY, Proposed Survey Site (from Sasarita, 2013, p. 2-2)

Using a portable spectrum analyzer and antenna in the omni-directional mode,

radio frequency spectrum scans were performed from 10 kilohertz (kHz) to 6 gigahertz

(GHz) at the edge of the safety zone of the wind turbine, and initial readings downwind

of the wind turbine (the back of the nacelle) were taken (Sasarita, 2013, p. 2-1). If the

predominant wind changed, during the course of a test run, the change on the data

collection sheet was noted. (p. 2-1)

NOTE: This frequency range was selected for two reasons: 1) these frequencies

are the most likely to be impacted, and 2) these frequencies cover all known terrestrial

tactical communications systems (Sasarita, 2013, p. 2-2).

Eliminate potential sources of interference if possible (Sasarita, 2013, p. 2-2).

“Cell phones and portable radios were left in a vehicle at least 50 feet from the data

collector” (p. 2-2). If a DC-AC inverter was used to power the spectrum analyzer and

laptop, use a 100-foot extension cord and locate the vehicle on the opposite side of the

data collector from the turbine, at approximate a 45-degree angle from the line between

the data collector and the turbine (p. 2-2). This will minimize any interference from the

vehicle with signals from the wind turbine (p. 2-2).

Perform scans as follows, in Table 1.

Table 1. Warren AFB Survey Frequency Bands (from Sasarita, 2013, p. 2-2)

Frequency Band

Resolution BW

Video BW

Antenna

10 kHz–100 kHz

100 Hz

300 HZ

LF Loop

100 kHz–2 MHz

300 Hz

1 kHz

HF Loop

2 MHz–80 MHz

3 kHz

10 kHz

HF Loop

80 MHz–200 MHz

3 kHz

10 kHz

VHF Loop

200 MHz–1 GHz

10 kHz

30 kHz

VHF Loop

b.

Settings

•

The Rohde & Schwarz FSH6 shall have attenuation set to 0 dB with the

preamp turned on (Sasarita, 2013, p. 2-3).

•

Record the data from the above scans using the Rohde & Schwarz FSH

View software program (Sasarita, 2013, p. 2-3).

If RF unidentified noise is detected, switch from an omni to a directional antenna

and determine if the signal is coming from the direction of the wind turbine (Sasarita,

2013, p. 2-3). If so, move so that the turbine is at a right angle to the previous noise

bearing (p. 2-3). If the direction of the RF noise moves to correspond to the new bearing

of the turbine, move closer and farther away from the turbine and measure amplitude

changes of the noise (p. 2-3).

If RF noise is detected and appears to be emanating from the wind turbine, turn

the turbine off and back on to see if the noise goes away and returns (Sasarita, 2013, p. 2-

3). Record the “off” state as well as the “on” state (p. 2-3).

If the RF noise is determined to be coming from the wind turbine (generator,

transformer, inverter, or tower) or feeder power lines (Sasarita, 2013, p. 2-3):

•

Use the directional antenna to determine if it is originating at the top of the

tower (generator in the nacelle), the base (transformer or inverter), the

tower itself, or the power lines. Move closer or farther away as required to

isolate the noise source (Sasarita, 2013, p. 2-3)

•

Zoom in to the frequency of the RF noise and capture the analyzer screen

•

Use the earphones to listen to and describe the noise

Repeat all of the above to identify any additional RF noise. Test all three available

turbines and the feeder power lines at Warren AFB, WY (Sasarita, 2013, p. 2-3).

For comparison purposes, perform an additional scan set at a distance at least 250

feet away from the turbine (Sasarita, 2013, p. 2-3).

If time is available and permission is obtained, perform spot check scans in the

vicinity of the Happy Jack Wind Farm located approximately 10 miles west of Cheyenne,

WY (Sasarita, 2013, p. 2-3). Spot check scans to include frequencies of interest resulting

from the scans at Warren AFB (p. 2-3).

Repeat for additional sites as they become available (Sasarita, 2013, p. 2-3).

3.

Findings

“Warren AFB has three wind turbines, two Vestas 660 KW turbines and one

Gamesa Pennsylvania 2 MW turbine” (Sasarita, 2013, p. 2-3).

•

The 2 MW turbine was non-operational at the time so we could not survey

it (Sasarita, 2013, p. 2-3)

•

An Electromagnetic Survey was conducted inside the tower of, adjacent

to, and at a far field distance from, one of the operational 660 KW turbines

at Warren AFB. Measurements were made with both 660 KW turbines

running, with only the closest turbine running, and with both turbines

stopped. (Sasarita, 2013, p. 2-3)

•

An Electromagnetic Survey was also conducted at the Happy Jack Wind

Power Project, approximately nine miles west of Warren AFB. This site

consisted of 14 Suzlon S88 2.1 MW wind turbines. Because the wind farm

site chief was off site for the day, we were unable to directly approach any

of the turbines. We were, however, able to gain permission to conduct the

survey from the Cheyenne Landfill that is near the center of the wind

farm. The survey site was near the Southwest corner of the Eastern half of

the wind farm. The nearest three turbines were all within approximately

600 meters of the survey site. (Sasarita, 2013, pp. 2-3 – 2-4)

Measurements were taken using a Rohde and Schwarz FSH-6 spectrum analyzer

and a tripod-mounted locally produced multi-band loop antenna (Sasarita, 2013, p. 2-3).

Measurements were taken alternatively with the antenna horizontally polarized (omni-

directional) and vertically polarized (bi-directional).

Measurements within the 660 KW turbine tower at Warren AFB with the door

closed and the turbine running did reveal several detectable emanations, but at a level

within the tower that were at or below the noise floor outside the tower.

No significant electromagnetic emanations were detected outside the tower at

either the far field distance (approximately 150 yards) or immediately adjacent to the

tower (less than 10 yards) (Sasarita, 2013, p. 2-4). “There was no measurable difference

between the turbines running and the turbines stopped” (p. 2-4)

No measurable electromagnetic emanations were detected at the wind farm

(Sasarita, 2013, p. 2-4).

4.

Technical Analysis

No significant electromagnetic emanations were detected outside the Vestas 660

KW turbine tower at either the far field distance (approximately 150 yards) or

immediately adjacent to the tower (less than 10 yards) (Sasarita, 2013, p. 2-4). There was

no measurable difference between the turbines running and the turbines stopped (p. 2-4).

The plots in Figures 5 and 6 graphically support the conclusion that no significant

electromagnetic emanations were detected outside the towers (Sasarita, 2013, p. 2-4). In

these plots, the red line is when the turbine was on and the blue is when it was off (p. 2-

4). There is no significant difference between the two.

Measurements within the 660 KW turbine tower at Warren AFB with the door

closed and the turbine running did reveal several detectable emanations; however, they

were at a level within the tower that were at or below the noise floor outside the tower

(i.e., the emanations could only be seen when the noise level was significantly reduced by

going inside the tower and closing the door).

Figure 5. 100 kHz to 2 MHz, Red is Wind Turbine on and Blue Is Wind Turbine Off

(from Sasarita, 2013, p. 2-4)

Figure 6. 2 MHz to 80 MHz, Red Is Wind Turbine on and Blue Is Wind Turbine Off

(from Sasarita, 2013, p. 2-5)

In document FACULTAD LATINOAMERICANA DE CIENCIAS SOCIALES SEDE MÉXICO Maestría en Gobierno y Asuntos Públicos XIII Promoción (página 33-38)