Digital twins

When wind turbine blades need a doctor

Inspecting wind turbine blades for damage is a complex and time-consuming task. By combining three well-established technologies, researchers at DTU have developed a solution that can detect damage requiring repair while the turbine is still in operation. This can lead to savings of up to 50 percent.

Associate Professor Xiao Chen is the originator of a system developed at DTU Wind that can inspect a wind turbine’s blades for critical damage – while it is in operation. Photo: Bax Lindhardt.

Facts

  • Drones equipped with thermal cameras inspect wind turbine blades during normal operation and testing.
  • An AI algorithm analyses both thermal and standard RGB images and registers potential damage while monitoring its development.
  • The system provides experts with a well-founded decision-making basis in—almost—real time.
  • The system has been used to inspect more than 50 wind turbines in Germany, Sweden, Denmark, France, and Portugal. It has detected anomalies in blades that were invisible to the human eye and might otherwise have gone unnoticed. The DTU team is currently further advancing the technology for blade certification testing and for blade manufacturing quality control—processes that would also normally require production to be stopped.
     

Three-in-one technologies

  • Thermography: Imaging of temperature differences within a structure. 
  • Computer vision: AI algorithms that detect, classify, and measure patterns in image data.
  • Drones: Standard commercial drones
     

Simple solution with major impact

AQUADA can identify damage requiring repair in real time. When a crack in the blade material moves under load, it causes a temperature increase, leaving a trace. The thermal camera captures images of friction heat and translates it into variations in red colour in images of the blades.

The AI model developed by Xiao Chen and his team analyses images and identifies potentially critical damage. This provides a stronger basis for decision-making when a specialist must determine whether damage should be repaired immediately or postponed.

“We can also say what does not need attention, which helps avoid unnecessary shutdowns,” he explains.

The method saves both time and money, while enabling more green electricity to be generated from existing wind turbines, since the turbines no longer need to be stopped for inspection, as is the case today. Offshore wind turbine inspections currently require technicians to travel by vessel and carry out manual inspections, and such routine inspections are typically conducted once a year—or, as in France, every six months—for each individual turbine. The costs quickly add up.

“With this solution, we avoid costly shutdowns and manual inspections. This means faster and safer monitoring, increased energy production, and inspection costs reduced by up to 50 per cent,” says Xiao Chen.

Off-the-shelf hardware plus unique data

The solution combines drones, thermography—which captures images by measuring thermal radiation—and computer vision, a field within artificial intelligence. The drones replace manual inspections, the thermal camera visualizes where potential damage occurs, and computer vision identifies patterns, pinpoints the damage, and quantifies its progression.

AQUADA is easy to use: the drone and camera are standard, commercially available equipment that users can purchase and operate themselves using a guide. The user then sends the recordings to AQUADA, which processes the data and flags potential critical damage both on and beneath the blade surface. A specialist subsequently decides whether the damage requires immediate repair or can be deferred.

From detection to prognosis

“AQUADA cannot yet predict when damage should be repaired. Training the technology to do that is the next step,” says Xiao Chen.

“This requires a different resolution and significantly more data,” he explains. And here arises a paradox: fortunately, critical damage is very rare. That is good news for wind turbines, but challenging for an AI model that relies on examples for training.

The location and shape of a crack affect the structure in different ways. Therefore, much more data is needed to predict how a crack will develop.

“If an image can indicate that a crack should be repaired in three months rather than immediately, it enables planning and optimization. This further reduces operation and maintenance costs and keeps production running,” Xiao Chen concludes.

The AQUADA technology has already been adopted by industry, which has also been involved throughout the development process.

The images captured by the thermal camera mounted on a drone are transmitted directly to a programme capable of detecting damage that may require repair. The damage appears as red blotches on the blades.

Fakta

  • AQUADA: a method developed at the Technical University of Denmark (DTU) and subsequently enhanced into advanced solutions
  • AQUADA-PLUS: an enhanced version of the AQUADA method to enable monitoring of multiple damage types simultaneously
  • AQUADA-GO: a development and demonstration project based on the AQUADA method focusing on the application of wind turbines in operation in collaboration with RWE, Statkraft, TotalEnergies, Quali Drone, Energy Cluster Denmark, and EUDP
  • AQUADA170m+: a development and demonstration project based on the AQUADA method focusing on the application of a market-ready solution for the largest blades at commercial test centres, supported by EUDP and developed with Blaest A/S
  • Future plans include AQUADA-MAC, integrating the technology directly into blade manufacturing for quality control
     

Read more on AQUADA's website.

Contact

Xiao Chen

Xiao Chen Head of Section Department of Wind and Energy Systems Mobile: +45 93513567