Failed anemometer

Understanding what the WindESCo failed anemometer issue check is for

What is the purpose of the turbine issue check?

• The anemometer on a given turbine appears to have failed and is providing unreliable wind speed and direction measurements.
• If the anemometer has failed, the turbine may be incorrectly cutting-in, cutting-out, or yawing non-optimally.

What does this look like?

• The failed anemometer can be identified in several ways, but a clear one is through the yaw misalignment estimate that was previously consistent, but is now deviating from typical behavior
  • For WindESCo, this has typically been indicative of a failure or impending failure

• A failed anemometer can also sometimes be identified by comparing rated power among peers and identifying discrepancies.
• In this case the anemometer (and therefore NTF) was biased low for 7 turbines

How can you tell the issue is corrected?

• This issue is corrected when the anemometer is replaced.  In that case there would be a consistent yaw misalignment (or none) identified, and the median power would be consistent among turbines.
• For the 7 impacted turbines (second example), the anemometers were corrected and the NTF was recalibrated.
• This corrected the performance at cutout wind speeds associated to a $40,000/yr benefit for the site