Minimum pitch inconsistent over time

Understanding the "Minimum pitch inconsistent over time" check

What is the purpose of the turbine issue check?

• A given turbine has a mininum pitch values that changes over time, either continuously, intermittently, or with discrete change points.
• Optimum minimum pitch depends on many wind farm specific factors including nominal air density, turbulence, blade surface conditions, and blade modifications. The pitch angle settings in region 2 of the power curve impact the angle of attack and efficiency of the rotor blades.

Can you see this in 10-min data? 

• This issue can be identified in 10-minute data by plotting the minimum pitch over time

What does this look like / How do you identify this issue?

• In this example we can see the deviation of the minimum pitch in March 2022 and then again in May 2022.
• This discrepancy impacted 120 turbines on the site

How can you tell the issue is corrected?

• This issue is corrected when all turbines maintain a consistent minimum pitch and seasonal pitch settings are as expected (and repeatable over time).
• In this case the minimum pitch setting was incorrectly set which caused a loss of 0.5% AEP per turbine.
• Consistent application of the parameter settings correlated to $240,000 / year benefit for the site