AT LOFTY HEIGHTS: 3D SCAN OF A WIND TURBINE BLADE

The maintenance of wind turbines, and whole wind farms, is a challenge. Normally wind turbines are designed to operate for 20 years. During these 20 years they are subjected to all kinds of weather conditions and heavy loads, but thanks to modern acquisition technology and advanced numerical models, such conditions can be addressed and even turned into increased annual energy production.

To optimize the production throughout their lifetime, their operating conditions must be understood in detail and then regularly maintained on this basis. The goal is to keep wear and tear under control and prevent the generation of unexpected vibrations and/or weak points that could compromise the integrity of the turbine structure and components, all while maximizing the power production.

The Spanish company Nabla Wind Power is part of the Nabla Wind Hub group, an independent service provider that offers unique and multitechnology solutions for wind farms life extension, performance improvement and maintenance optimization.

Digitalization under harsh conditions

In 2020 Nabla Wind Power was asked to extend the rotor blades of a wind turbine to increase the performance of the existing installation by 10%. To do this, the last meters of one rotor blade had to be digitalized so that the blade extension could be subsequently designed. In a first attempt, terrestrial laser scanners were used for the digitalization. But Nabla needed a considerably lower uncertainty in the measurements and therefore started to look for an alternative solution and finally asked Creaform Services to support them.

Scan preparation: Industrial climber sticking the targets on the blade

The best portable 3D scanner suited for this task was the HandySCAN 3D | BLACK. Thanks to its dynamic referencing feature, it can digitalize precisely in harsh conditions. Vibrations do not affect the results and the uncertainty of the measurements is far less than a millimeter. As the task had to be realized directly on the wind turbine, a Creaform Application Engineer trained two industrial climbers from the company Asaken and taught them how to use the HandySCAN 3D. Then the climbers went up to the top of the wind turbine at 130 meters, had to get out of the hub and rappel down to 65 meters above the ground.

The first thing to do was to stick targets on one of the rotor blades on the last 7 meters. These targets are used as reference points by the HandySCAN 3D. Then they started the scan. While one of the industrial climbers was wearing the laptop, the other was handling the scanner. Meanwhile, the Creaform Application Engineer was overviewing the scan from the ground via Teamviewer. At this height, wind conditions are always an issue and several times, it became so windy that the works had to be stopped due to the strong winds. Also, some technical issues of the wind turbine itself disturbed the scan process: for example, the rotor blocked and couldn’t be brought into a vertical position. But finally, the scan was performed successfully.

The acquisition software used was VXmodel, a module of VXelements. The generated .stl file was then transferred into CATIA for reverse engineering.

Scan in VXelements with mesh visualization

CAD of the reversed engineered rotor blade in CATIA

Nabla’s Head of Operation, Eder Murga, was really pleased with results: “The handling of the provided service was professional, both from Creaform and Asaken. Despite the harsh conditions and many interruptions due to strong winds, everyone involved faced the change in conditions with great flexibility and, in the end, we managed to get the perfect results. A hand-held, self-referencing measuring system such as the HandySCAN 3D is the only way to carry out such a measurement in a harsh environment.”