Dynamic Wind Farm Flow Control

WHY

By extracting kinetic energy from the wind flow, a wind turbine reduces the wind speed in a wake that forms downstream of the wind turbine rotor. In a wind farm, in which turbines are placed relatively close to each other, this wake effect can reduce the power production of downstream turbines.

Nowadays, in wind farms, wind turbines operate on an individual level in which each wind turbine optimises its power production. Existing algorithms for wind farm flow control, primarily through wake steering, are based on steady-state engineering models that neglect the dynamics of the wind farm. This results in sub-optimal power output at wind farm level. Flow or wake control, coordinated by a wind farm controller, will result in a higher energy yield of the wind farm.

WHAT

Innovation project ‘Dynamic Wind Farm Flow Control’ aims to take the crucial next step in the effort to minimise wake effects for modern wind farms like Hollandse Kust Noord in time-varying atmospheric conditions. The project will further develop and implement closed-loop active wake steering (based on yaw control) in combination with the novel HELIX active wake mixing technology. The main goal is to mature these technologies and demonstrate these at the offshore wind farm Hollandse Kust Noord. We will demonstrate that by including the dynamic flow control a larger potential power output can be gained.

The HELIX technology will be explored in more depth using desktop and computational studies. We will make use of high-fidelity computational fluid dynamics studies and detailed loads analysis. These modelling results will be compared with results from wind tunnel experiments. The HELIX technology is subsequently tested experimentally at an onshore research wind turbine. When successful, the HELIX technology will be implemented at one of the SG 11.0-200 DD wind turbines at Hollandse Kust Noord wind farm. In parallel, the closed-loop active wake steering technology will be demonstrated at the wind farm. As a result, both technologies will be matured from TRL3 to TRL7.

The final phase of the project focuses on the potential impact when these control technologies are rolled out across the full wind farm and how these control technologies can impact the design and power production of future wind farms.

EXPECTED RESULTS

In this project, we will unleash the true potential of the novel HELIX active wake mixing concept by detailed experiments and field trials, while the closed-loop wind farm control technology is further matured. The technology maturation and validations are of crucial importance for the wide adoption of the concept by wind farm developers and operators. It has the potential to further drive down the LCOE of wind and improve the controllability of the flow.

We expect the project to result in three major improvements.

• When applied to a full wind farm, the annual wind farm power output is expected to increase in the order of 2 - 3%.
• With wind farm power output control, more stable and more predictable power output is expected with decreased dependence on apparent wind speed and wind direction.
• The wind farm power density (GWh/km2) of utilized offshore space to increase by a factor of two as a decreased distances between turbines can be applied.