The EWIC project will demonstrate how the value of end of warranty inspections can be enhanced – with the overall objective to reduce LCoE and extend the operational lifetime of the blades.
Currently, there are no official statistics of structural damages on the blades and especially not for newer turbines where the failure rate is significant higher than for small turbines. However, the area is of high importance to the wind turbine owners and a well-known fact. Still most of inspections are performed on the outside of the blade, which only shows the “top of the iceberg”. Inspecting inside the blade, in the areas that are critical, will show the small part underneath the “iceberg”, and if NDT are used, a higher picture of the damages will be shown. Often, the results of inadequate inspection are formation of structural damages, that in worst case leads to blade failure or total turbine failure. Visualization by Kirt x Thomsen
Vattenfall, E.ON, HOFOR together with The Blade Group Network – consisting of more than 30 wind turbine owners – have strongly encouraged that new concepts for the inspection of turbine blades at the end of warranty need to be developed. Their wish is to profoundly incorporate results of the latest research activities and extensive field experience in this work.
The wind turbine owners have teamed up with OffshoreEnergy.dk, Bladena, Total Wind BLAEST, Kirt-Thomsen and FORCE Technology to achieve this objective – optimize the quality of the blade inspection method and develop a common understanding/standard for how this work should be done in the future.
Anders Søe-Jensen, CEO at Bladena and former CEO of GE Offshore and Vestas Offshore, says:
“As a standard, blades have for many years been inspected from the outside without any internal inspections. We know today, that even if the blade surface looks intact there may be serious issues to be found on the inside of the blades and even inside the panel structures. Therefore, the implementation of new inspection methods is to extend the lifetime by reducing maintenance costs and minimizing the future down-time.”
Hence, the EWIC project partners have agreed to thoroughly investigate options for inspections of the blades from the inside and inside the material.
The project will define the details of how inside visual inspections should be carried out. The deployment of small size cameras and NDT in critical areas will be explored.
Visual inspection and NDT techniques will be combined with knowledge about theoretical failure modes, failure modes found in the laboratory tests and with data from blades damaged in the field. This will allow the definition of an optimal strategy for the use of NDT methods such as thermography and ultrasound in selected areas.
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