Fraunhofer Institute for Wind Energy SystemsAt a glance
- Lightning damage is one of the most common types of damage to wind turbines. However, it is often only discovered late and can usually only be assessed by opening the rotor blade. This leads to high costs for operators.
- In the ModulBlitz research project, the project partners are working on a holistically automated process extending from the detection of lightning striking the structure to the assessment of the damage and its impact on the rotor blade’s remaining service-life.
- Fraunhofer IWES is responsible for the process for generating artificial, realistic lightning damage on rotor blades as well as the integration of the further-developed detection process into existing measuring technology.
The challenge
Lightning damage to rotor blades is the second-most-common type of damage to wind turbines. Although rotor blades are equipped with lightning conductors, the systems are not always capable of dissipating the energy optimally. If damage is not detected rapidly, the result can be high yield losses because of costly consequential damage or complete failure of the rotor blade. However, even if the rotor blades are inspected regularly, the extent of damage is often only identifiable following mechanical processing such as removal of the coating to reveal the internal structure. Superficially minor damage can cause severe damage to the critical internal areas of a rotor blade and shorten its remaining service life decisively.
The solution
This is where the ModulBlitz research project comes in. The focus is on the detection, localization, and assessment of lightning damage to rotor blades as well as its impact on the structure and the resulting fatigue behavior. The primary goal of the project is to develop a holistically automated process extending from the detection of lightning striking the structure to the assessment of the damage in the context of the blade’s remaining service life. This process should be integrated into existing structural health monitoring (SHM) systems.
The scientists will do so by first developing a process for controlled generation of lightning damage on a demonstrator. Using three 15-meter-long blade tips, two of which will be damaged in the high-voltage testing, the test procedure developed in the preceding project MultiMonitorRB is to be adapted for the test setup and strategy.
In addition, structural monitoring and testing methods for the damaged rotor blade tips will be further developed to allow conclusions to be drawn about the time and place the lightning damage occurred. Material characterization testing and new models should contribute to being able to qualify the extent of the damage and its impact on the remaining service life of the structure under investigation in more detail. Furthermore, SHM systems will be installed in the wind farm.
Fraunhofer IWES is responsible for the process for the generation of artificial, realistic lightning damage to the blades and the production of rotor blade tips among other tasks. In addition, Fraunhofer IWES will develop a concept for the integration of the further developed measuring and monitoring processes into existing measuring technology.
The added value
The insights gained in the ModulBlitz research project will contribute to the automatic and thus considerably quicker detection of possible damage caused to rotor blades by lightning strikes. The further development of detection methods will make it possible to assess the actual extent of damage without opening the rotor blade. This will help to avoid downtimes and establish a basis for early, cost-effective, and efficient repairs. Given the immense costs associated with lightning strikes to rotor blades, this translates to significant financial relief for operators. As such, ModulBlitz will increase the availability and economic efficiency of wind turbines and support climate-neutral power generation.
