Optimising energy yield of offshore wind farms: Active Wake Control

Active Wake Control increases the annual energy production of wind farms, while decreasing O&M costs

ECN’s Active Wake Control (AWC) is patented technology (more about our patents here and here) to operate offshore wind farms in such a way as to maximize the overall wind farm power production and reduce turbine loading. 

Why every wind farm operator and developer should look into the possibilities of AWC technology

  • AWC increases the wind farm annual power production (typically 0.5-2.5% depending on farm configuration)

  • AWC reduces fatigue loads on wind turbines (about 1-3%), increasing the lifetime by 4-20% while at the same time reducing failure rates (O&M costs saving)

  • Implementing AWC on a 350MW offshore wind farm could potentially result in around 20 GWh of additional power production and an increase in yearly cash flows of around 2 million euros for the operator (fast return on investment)

  • When used during the design phase of the wind farm, AWC reduces electrical infrastructure costs by reducing the spacing between the wind turbines. 

Benefits of pitch-based and yaw-based AWC

AWC consists of two concepts: pitch-based AWC and yaw-based AWC. The pitch-based AWC concept achieves increased power output by reducing the axial induction factor of the wind turbines at the windward side of the farm. This is achieved by pitching the blades of the upstream wind turbines or, equivalently, by derating them. This results in a net increase of power output of the farm and, at the same time, loads reduction. 

 The yaw-based AWC approach consists of operating upstream wind turbines with yaw misalignment with respect to the wind direction. It results in the wakes behind the yawed wind turbines being diverted away from the downwind wind turbines, as shown in this figure:

 

Yaw-based AWC moves the wake away from downstream wind turbines.

Current evidence supporting  expected benefits from Active Wake Control

  • Software results indicate that pitch-based  Active Wake Control can increase the power capture of a single row of wind turbines by up to 5% under optimal wind conditions.

  • Software results indicate that yaw-based  Active Wake Control can increase the power capture of a single row of wind turbines by up to 20% under optimal wind conditions.

  • Wind tunnel experiments with farm of small-scale wind turbines indicated energy increase by pitch-based Active Wake Control of 4.6%

  • Field measurements of pitch-based AWC indicated 5% power increase (turbines at about 4D spacing)

How can ECN help your business to increase the annual energy production of your windfarm?

Here’s how ECN can assist you:

  • We can perform numerical feasibility studies for wind farms, analyse the potential benefits from pitch-based and yaw-based AWC in terms of AEP increase and fatigue loads

  • We can perform dynamic simulations to determine an optimal strategy for dynamic adaptation of the pitch and yaw angle settings, maximising the benefits for the real-life time-varying wind resource

  • We can calibrate measurement equipment

  • We provide support with the implementation of AWC into the wind turbines and/or wind farm controller based on our 15-year experience in this field

  • We can perform accredited measurement campaigns

  • We can perform data analysis. 

For more information

Watch our animation to get a quick understanding of the principle of Active Wake Control:

The following publications give you more insight on Active Wake Control. For more publication on Active Wake Control, you can visit our publication database (keywords ‘Active Wake Control’ or ‘FarmFlow’).

  • Farmflow validation against full scale wind farms 
    For the accurate calculation of wind turbine wake effects in (large) offshore wind farms, ECN has developed the software tool FarmFlow. FarmFlow calculates the average velocities and turbulence intensities inside a wind farm. FarmFlow has proven to provide the highest accuracy for large offshore wind farms in comparison with other wake models. 

  • Active Wake Control by Pitch Adjustment
    This report gives a description of part of the work done within the framework of the FLOW project on Active Wake Control. Hereto available field measurements at the ECN wind turbine test site EWTW are analysed.

  • Dynamic Adaptation of Active Wake Control
    This report describes the effects of time-variations in the wind speed and direction on the benefits from Active Wake Control, and provides recommendations on how to implement Active Wake Control in the field to achieve a good balance between power production gain and actuator duty increase.

If you want to speak to someone from ECN about the possibilities of Active Wake Control for your business, please contact Glen Donnelly, Manager Business Development Wind Energy via our contact form.