The inspection of rotor blades and lightning protection systems on wind turbines using drones has rapidly gained in importance. The process not only saves costs, it can also significantly reduce the downtime of wind turbines.
The multi-stage drone system developed by the inspection body Deutsche Windtechnik for the inspection of rotor blades and lightning protection systems has been successfully validated. TÜV NORD has come to this conclusion as part of a conformity assessment that it has implemented for the first time.
Deutsche Windtechnik: first independent validation for an inspection body’s drone systema/strong> TÜV NORD certifies that the inspection body of Deutsche Windtechnik AG can record the technical condition of the rotor blades and the functionality of the lightning protection system of the rotor blades with the drone and assess their risks with regard to traffic and structural safety.This means that the drone system with the name “CU-RE” is also suitable for periodic inspections (WKP). “The validation by TÜV NORD confirms that the drone technology used by the Deutsche Windtechnik Inspection Body is suitable for carrying out a range of important inspections such as periodic and condition-oriented inspections,” says Matthias Brandt, CEO of Deutsche Windtechnik.
Inspection criteria according to TÜV standard TN-P-V01-001
“The inspection procedure was validated against our new TÜV Nord standard. This standard defines criteria and inspection points that allow drone inspection procedures to be evaluated,” explains Michael Lange, Head of the Conformity Assessment Body for Wind Energy according to ISO 17029 at TÜV NORD. For the validation of the Deutsche Windtechnik inspection body, the reliability of the processes was then assessed by means of documentation checks.
Continuously higher level of detail: Inspection using drones as part of the “CU-RE” three-stage model
If an upstream order-specific risk analysis was in favor of drone technology, the fully validated three-stage model called “CU-RE” (for “Close-Up and Review”) is used in the next step, according to Deutsche Windtechnik.
The model is based on the inspection specifications of the EASA (European Union Aviation Safety Agency) from the aviation industry. The first stage of the CU-RE system involves a general visual inspection using an automated drone flight, during which 100 percent of the outer surface of a rotor blade is scanned in order to identify any visible damage, defects or irregularities.
If necessary, the first stage can be supplemented at the second stage by manually guided drone technology deployed at specific points. If a more intensive inspection is also required, the third stage comes into play with the options of further specialized drone technology or rope access technology.
“Our experts decide whether a further inspection stage is necessary in order to be able to clearly identify any detected irregularities,” says Aeneas Noordanus, Sales Manager for Inspection Services at Deutsche Windtechnik, describing the process of successive in-depth inspections while constantly increasing the level of inspection detail.