What is pitch misalignment?

What is pitch misalignment in a wind turbine? 

Pitch misalignment occurs when all the blades of a wind turbine are not oriented at an identical pitch angle. Precise alignment of all wind turbine blades enables the turbine to capture the wind’s energy most efficiently.

The pitch misalignment of one or more blades is problematic and can lead to imbalanced rotor loads. This, in turn, causes increased fatigue loads and reduces annual energy production (AEP) by up to 0.7%.

What causes pitch misalignment? 

There are several causes of pitch misalignment. These include:

• Improper installation of one or more of the blades, or incorrect modification of their position during a maintenance outage.
• A skewed or miscalibrated zero-degree reference point, which establishes the blade position baseline.
• Faulty control system configurations that manage the wind turbine blade alignment.

Many of these factors are symptoms of an aging system.

How to correct pitch misalignment? 

Rotor imbalance detection algorithms embedded in the advanced control logic of a modern turbine control system can detect blade-to-blade misalignment and make corrections.

Rotor balance detection is included as part of Emerson’s standard wind turbine control system retrofit. When the system detects an imbalance, a correction is automatically made to the pitch setpoints to properly position the blades.

This solution can improve annual energy production by up to 0.7% and reduce fatigue loads to wind turbine rotors. Visit our wind turbine retrofit and wind turbine pitch control pages to learn more.