Wind energy is an increasingly important contributor of power within the renewable energy sector. In recent years there have been an increasing number of reports of defective blades contributing towards turbine failure. At present, regular costly inspections are conducted on turbine blades to ensure structural integrity and prevent degradation due to fatigue or impact. Within larger blade designs, there exists a complex composite structure of glass fibre reinforced plastic (GFRP) together with other materials.
Under normal operation conditions, annual maintenance costs for wind turbines are about 4%-5% of the capital investment. Approximately 30%-40% of these costs are inspection related. Nonetheless, annual maintenance costs can exceed in certain cases 10% of the overall value of the wind turbine if unpredicted damage is sustained by the turbine (e.g. unpredicted failure of the wind turbine blade). It should be noted that these costs do not take into account the costs incurred due to loss of production during downtime. As a result, O&M costs are attracting greater attention, as manufacturers attempt to lower these costs significantly by developing new turbine designs that require fewer regular service visits and less turbine downtime.
The WINTUR Demonstration Project looks to demonstrate the structural health monitoring (SHM) system that has already been developed successfully in the WinTur R4S project, in order to show that such a system is viable for blade monitoring and can help the wind sector to achieve the kind of energy delivery to business and communities that is desired by reducing operational and maintenance costs. The goal is to achieve this by increasing efficiency by way of realising the full life-cycle term of blade components and providing maintenance as and when it is required.
Key technical objectives of this demo project are:
1. Installation of novel light weight and flexible transducers on the blade able to detect the onset of damage that was the occurrence of fibre breakage due to staged development of a hole-defect
2. Combination of different NDT techniques based on guided wave ultrasonics such as Long Range Ultrasonic LRU and acoustic emission
3. A sequence of signal processing techniques (FFTs, averaging, amplification) to overcome problems of ultrasound attenuation
4. Utilisation of Energy Harvesting as a system to harness the surrounding environmental energy for the purposes of powering the sensors
5. Use of short-range wireless protocol techniques to transfer data from the pulser/receiver unit to the central control in the nacelle