Wind Turbine Yaw Misalignment

What is Wind Turbine Yaw Misalignment?

Yaw control systems are designed to adjust the rotor’s orientation to face the wind directly to efficiently generate electricity from wind force, a crucial capability for wind turbines. Wind turbine yaw misalignment occurs when the orientation of the turbine’s rotor is not aligned with the direction of the incoming wind.

When working as designed, the rotor faces the wind head-on so the blades can capture kinetic energy from the wind. Yaw control systems also ensure each turbine blade is subjected to equal force.

Misalignment can occur for a variety of reasons, including inaccurate wind detection, mechanical issues, or the yaw control system’s ability to respond to changing directions. 

Infrequent or inaccurate turbine inspections can result in overlooking these issues and lead to additional problems. Conducting accurate and timely wind turbine inspections is one important step to preventing misalignment.

Static vs Dynamic Misalignment

Identifying which type of misalignment is affecting a specific turbine is necessary to implement corrective actions. There are two general categories of yaw misalignment to be aware of, which are:

  1. Static yaw misalignment: A static misalignment is a persistent offset in orientation that does not change in response to wind direction or over time. These misalignments are often the result of incorrect installation, design issues, or calibration errors.
  2. Dynamic yaw misalignment: Conversely, dynamic misalignment involves changes in yaw orientation over time, typically in response to changing wind directions. Sensory accuracy, turbulence, and control system delays can create this error.

Wind Turbine Issues Caused by Yaw Misalignment

How can yaw misalignment affect a wind turbine’s overall performance and health? Several problems can arise when misalignment is left unchecked.

Unfortunately, detecting yaw misalignment can often be challenging, depending on the technologies and inspection techniques used throughout wind farm management. Adopting digital twins and autonomous drone inspections goes far in quickly identifying yaw misalignment issues.

Reduced Power Generation

One of the most immediate effects of misalignment is power loss due to not capturing wind loads as designed. Identifying a reduction in power generation can often result in discovering yaw misalignment. 

Yaw misalignment and power curve analysis help technicians understand the severity of the misalignment. Power loss can be proportional to cos^2 * theta, with theta representing the misalignment angle.

Over time, unchecked alignment can worsen, decreasing total power generation. Frequent inspections and maintenance schedules are crucial to maintaining optimal power generation.

Uneven Wind Loads

Misalignment places uneven wind loads on individual blades with each rotation. While this damage isn’t usually severe at first, it can create significant mechanical stress and faster wear and tear over time.

Blades, the nacelle, and rotors can all be damaged with ongoing yaw misalignment. Depending on severity, this damage can decrease the total lifespan of the tower, each component, and higher maintenance costs.

Structural Concerns

Wind turbines are highly complex structures intended to withstand some of Earth’s most extreme wind loads. However, if one component malfunctions, it can quickly affect the turbine’s structural integrity.

Yaw misalignment disrupts the aerodynamic behavior of the entire turbine. If it becomes severe enough, misalignment can cause a variety of harmful behaviors as components are subjected to unwanted conditions. Identifying and addressing misalignment before it becomes severe is critical.

How to Address Yaw Misalignment

Yaw misalignment can occur from several sources and may be static or dynamic. Once identified, how can you address yaw misalignment? While not an all-inclusive list, a few ways to address this issue are:

  • Ensure accuracy of wind direction sensors: Detecting the direction of the wind is crucial to aligning the turbine blades with the wind. Flaws or defects in these sensors can cause yaw misalignment, as other systems are working with faulty data. 
  • Advanced control systems: If wind sensors are functioning as expected, they will depend on control systems to adjust the yaw and rotor accordingly. Flaws in this system can result in both dynamic and static misalignment, making it a prime area to investigate once misalignment is identified.
  • Regular inspection and maintenance: Prevention is the first line of defense for yaw misalignment. Frequent inspections and maintenance may identify yaw misalignment or other issues that will later result in misalignment. Adopting advanced technologies like digital twins and AI-powered analytics can go far in preventing misalignment.