By Jakob Brodersen. Translated by Pernille Budde Haensel, AAU Communication
Photo: Line Jørgensen
Damage to wind turbine blades is one of the biggest challenges of using wind as a source of renewable energy. The load on the blades is enormous so to ensure safe and stable operation, regular maintenance is vital to detect any signs of damage.
Maintenance typically involves manual inspection where the turbine is first switched off, after which a technician climbs up and is lowered on a rope to one blade at a time. Such maintenance is both dangerous and costly. Not only is it labour intensive, it is also costly because the turbine is not producing power during maintenance. However, new technology may result in manual inspections being a thing of the past.
Bilal Ali Qadri, Research Assistant in the Department of Civil Engineering at Aalborg University Esbjerg, has developed a new method for monitoring turbine blades together with his supervisor, Martin Dalgaard Ulriksen, Assistant Professor. Wind turbine blades are monitored through built-in sensors which constantly transmit data on blade movement to a control centre.
In this way, even the slightest change or abnormal movement is quickly detected. If everything runs smoothly, costly manual inspections can be avoided, and when any irregularities are detected, it can be solved before becoming a serious problem.
ACCURACY IN DAMAGE DETECTION
By combining statistical data with real-time data from the turbine blade sensors, Bilal Ali Qadri and Martin Dalgaard Ulriksen have made a mathematical model that shows how wind turbine blades move and vibrate under normal conditions and at different wind speed and temperature conditions.
The mathematical model and real-time data combined are the basis of the new technology that can quickly detect irregularities in blade movements – and accurately predict and locate blade damage.
‘We’ve managed to locate blade damage, which might become a problem in the future, with as little as five centimetres of accuracy –that’s how accurate the mathematical models we work with are. And we do this while the wind turbine is in operation,’ says Bilal Ali Qadri.
In the wind turbine industry, the economic benefits of using the technology called ‘vibration-based damage detection analysis’ are obvious. However, the potential for using the technology in other industries is great. Bilal Ali Qadri explains:
‘The next logical step is to examine whether the technology can be used to monitor irregularities in airplane wings. We assume that we’ll see some comparable patterns and challenges. Another area of interest is bridge structures. We believe vibration-based damage detection could help avoid major accidents and loss of life.
Bilal Ali Qadri's research project at Aalborg University Esbjerg is a collaboration with Brüel & Kjær, Vestas and Ramboll.