Structural health monitoring of wind turbine blades is challenging due to its large dimensions, as well as the complex and heterogeneous material system. In this article, we will introduce a radically new structural health monitoring approach that uses permanently installed radar sensors in the microwave and millimetre-wave frequency range for remote and in-service inspection of wind turbine blades. The radar sensor is placed at the tower of the wind turbine and irradiates the electromagnetic waves in the direction of the rotating blades. Experimental results for damage detection of complex structures will be presented in a laboratory environment for the case of a 10-mm-thick glass-fibre-reinforced plastic plate, as well as a real blade-tip sample.
CiangCCLeeJRBangHJ.Structural health monitoring for a wind turbine system: a review of damage detection methods. Meas Sci Technol2008; 19(12): 122001.
6.
MahafzaBR.Radar systems analysis and design using MATLAB. 3rd ed.London: CRC Press, 2013.
7.
LiCPengZHuangTYet al. A review on recent progress of portable short-range noncontact microwave radar systems. IEEE T Microw Theory2017; 65: 1692–1706, http://ieeexplore.ieee.org/document/7836309/
8.
SzczepanikRPrzysowaRSpychaaJet al. Application of blade-tip sensors to blade-vibration monitoring in gas turbines. In: RasulM (ed.) Thermal power plants. Rijeka: InTech, 2012, pp. 145–176.
9.
GuanSRiceJALiCet al. Structural displacement measurements using DC coupled radar with active transponder: DC radar with active transponder. Struct Control Hlth2016, http://doi.wiley.com/10.1002/stc.1909
10.
MollJBechtelKHilsBet al. Mechanical vibration sensing for structural health monitoring using a millimeter-wave doppler radar sensor. In: Proceedings of the 7th European workshop on structural health monitoring (EWSHM), Nantes, 8–11 July 2014, pp. 1802–1808.
11.
MollJMälzerMScholzNet al. Radar-based detection of birds near wind energy plants: first experiences from a field study. In Proceedings of the 10th German microwave conference, 14–16 March 2016, Bochum, pp. 239–242. IEEE.
12.
Munoz-FerrerasJMPengZTangYet al. Short-range doppler-radar signatures from industrial wind turbines: theory, simulations, and measurements. IEEE T Instrum Meas2016; 65(9): 2108–2119, http://ieeexplore.ieee.org/document/7487021/
ScholzMRediskeSNuberAet al. Radar-based non-destructive testing of wind turbine blades: first experiments from a laboratory study. In: Proceedings of the 8th European workshop on structural health monitoring, Bilbao, 5–8 July 2016, pp. 1–10.
17.
MollJKrozerV. Radar-based mechanical vibration sensing for structural health monitoring applications: a comparison of radar transceiver measurements at 24 Ghz and 100 Ghz. In: Proceedings of the 8th European workshop on structural health monitoring, 5–8 July 2016, Bilbao, pp. 1–6.
18.
SoumekhM.Synthetic aperture radar signal processing with MATLAB algorithms. New York: Wiley, 1999.
19.
MitraMGopalakrishnanS.Guided wave based structural health monitoring: a review. Smart Mater Struct2016; 25(5): 053001.
20.
MollJMälzerMKrozerVet al. Activity monitoring of bats in a laboratory flight tunnel using a 24 GHz FMCW radar system. In: Proceedings of the 11th European conference on antennas and propagation, Paris, 19–24 March 2017, pp. 2541–2545. IEEE.
21.
MollJMälzerMSimonJet al. Field demonstration of radar-based SHM of wind turbine blades at a 2 MW wind turbine: installation, data acquisition and signal analysis. In: Proceedings of the 11th international workshop on structural health monitoring, Stanford, CA, 12–14 September 2017, pp. 1–8.
22.
ArnoldPMollJKrozerV.Design of a sparse antenna array for radar-based structural health monitoring of wind turbine blades. IET Radar Sonar Nav. Epub ahead of print 17 April 2017. DOI: 10.1049/iet-rsn.2016.0355.
