A new innovative radar technology from the Fraunhofer Institute for Applied Solid State Physics IAF creates wind turbine efficiencies and reduces costs in production and operation.
One of the most important parts of wind turbines in the production of energy are the blades, which are typically made from glass fiber and carbon fiber reinforced plastics (GFRP / CFRP). They need to be very flexible, and able to withstand incredible pressure from gusts of wind.
Each blade can be made up of up to 100 sheets of glass fiber webbing, and quality control is essential at this part of production. Any small defects can create additional friction against the wind which reduces the amount of power generated by the wind turbine.
Coordinator of the radar project and group manager of sensor systems at the Fraunhofer IAF., Dr. Axel Hülsmann said, “The difficulty lies in layering the glass fiber sheets flat before they are glued, without creating undulations and folds, and avoiding the formation of lumps of resin or sections of laminate which don’t set when applying the epoxy.” The Fraunhofer IAF material scanner was created in order to help identify these defects during manufacturing.
According to the press release, ‘At the core of the material scanner is a high frequency radar, which operates in the W band between 85 and 100 GHz with only very few watts of transmitting power. Specialized software is then used to process the transmitter and receiver signals and visualize the measurement results.’
Hülsmann notes, “This enables us to generate a cross-sectional view of the blade, in which defects can be identified in the millimeter range, and makes our material scanner significantly more accurate than conventional methods.”
Not to mention alternative methods can be more difficult to carry out, like ultrasound solutions, where water or gel must be used.
Hülsmann said, “Water or gel has to be utilized as a coupling agent, as every air pocket between the sensor and measured part muffles the ultrasound signal to a considerable extent. While this entails certain side effects, it is nonetheless possible when checking for defects during rotor blade production. But applying water or gel to wind turbine blades which are 100 meters in the air is extremely complicated. Because it allows for non-contact remote sensing, radar is the optimal solution in this case.”
If you want to see this technology in action, you can visit Fraunhofer IAF at the Hannover Messe, hall 17, booth B76, from April 24–28, 2017.