- Volume 21 Issue 6
DOI QR Code
Vibration-based structural health monitoring for offshore wind turbines - Experimental validation of stochastic subspace algorithms
- Received : 2015.12.03
- Accepted : 2015.12.09
- Published : 2015.12.25
The efficiency of wind turbines (WT) is primarily reflected in their ability to generate electricity at any time. Downtimes of WTs due to "conventional" inspections are cost-intensive and undesirable for investors. For this reason, there is a need for structural health monitoring (SHM) systems, to enable service and maintenance on demand and to increase the inspection intervals. In general, monitoring increases the cost effectiveness of WTs. This publication concentrates on the application of two vibration-based SHM algorithms for stability and structural change monitoring of offshore WTs. Only data driven, output-only algorithms based on stochastic subspace identification (SSI) in time domain are considered. The centerpiece of this paper deals with the rough mathematical description of the dynamic behavior of offshore WTs and with the basic presentation of stochastic subspace-based algorithms and their application to these structures. Due to the early stage of the industrial application of SHM on offshore WT on the one side and the required confidentiality to the plant manufacturer and operator on the other side, up to now it is not possible to analyze different isolated structural damages resp. changes in a systematic manner, directly by means of in-situ measurement and to make these "acknowledgements" publicly available. For this reason, the sensitivity of the methods for monitoring purposes are demonstrated through their application on long time measurements from a 1:10 large scale test rig of an offshore WT under different conditions: undamaged, different levels of loosened bolt connections between tower parts, different levels of fouling, scouring and structure inclination. The limitation and further requirements for the approaches and their applicability on real foundations are discussed along the paper.
offshore wind turbine;structural health monitoring;stochastic subspace identification
- Balageas, D., Fritzen, C.P. and Guemes, A. (2006), Structural Health Monitoring, Hermes Science Publishing.
- Basseville, M., Abdelghani, M. and Benveniste, A. (2000), "Subspace-based fault detection algorithms for vibration monitoring", Automatica, 36, 101-109. https://doi.org/10.1016/S0005-1098(99)00093-X
- Doebling, S.W., Farrar, C.R., Prime, M.B. and Shevitz, D.W. (1996), Damage Identification and Health Monitoring of Structural and Mechanical Systems from Changes in Their Vibration Characteristics: A Literature Review, Report LA-13070-MS, Los Alamos, USA.
- Fritzen, C.P., Klinkov, M. and Kraemer, P. (2013a), "Vibration-based damage diagnosis and monitoring of external load", New Trend. Struct. Health Monit., 542, Springer.
- Fritzen, C.P., Kraemer, P. and Buthe, I. (2013b), "Vibration-based damage detection under changing environmental and operational conditions", Adv. Sci. Technol., 83, 95-104.
- Fritzen, C.P. and Kraemer, P. (2009), "Self-diagnosis of smart structures based on dynamical properties", Mech. Syst. Signal Pr., 23, 1830-1845. https://doi.org/10.1016/j.ymssp.2009.01.006
- Fritzen, C.P., Kraemer, P. and Klinkov, M. (2010), "Schwingungsbasierte Schadensdiagnose fur Offshore-Windenergieanlagen", Proceedings of the Schwingungsanalyse & Identifikation, Leonberg, Germany.
- Iliopoulos, A., Shirzadeh, R., Weijtjens, W., Guillaume, P., Van Hemelrijck, D. and Devriendt, C. (2016), "A modal decomposition and expansion approach for prediction of dynamic responses on a monopile offshore wind turbine using a limited number of vibration sensors", to be published in Mech. Syst. Signal Pr., 68-69, 84-104. https://doi.org/10.1016/j.ymssp.2015.07.016
- Kraemer, P. (2011), Damage diagnosis approaches for structural health and condition monitoring of offshore wind energy plants, PhD Thesis, University of Siegen.
- Kraemer, P. and Fritzen, C.P. (2008), "Sensor fault detection and signal reconstruction using mutual information and Kalman filters", Proceedings of the International Conference on Noise and Vibration Engineering, Leuven, Belgium.
- Kraemer, P. and Fritzen, C.P. (2010), "Aspects of operational modal analysis for structures of offshore wind energy plants", Struct. Dynam. Renew. Energy, 145-152.
- Link, M. and Weiland, M. (2014), "Structural health monitoring of the monopile foundation structure of an offshore wind turbine", Proceedings of the EURODYN 2014, Porto, Portugal.
- Peeters, B. and De Roeck, G. (1999), "Reference-based stochastic subspace identification for output-only modal analysis", Mech. Syst. Signal Pr., 12(6), 855-878.
- Van Overschee P. and De Moor, B. (1996), Subspace Identification for Linear Systems, Theory, Implementation, Applications, Kluwer Academic Publishers.
- Weijtjens, W., Verbelen, T., De Sitter, G. and Devriendt, C. (2015), "Foundation structural health monitoring of an offshore wind turbine - a full-scale case study", Struct. Health Monit., 1-14.
- Fatigue Crack Detection for Lifetime Extension of Monopile-based Offshore Wind Turbines vol.137, 2017, https://doi.org/10.1016/j.egypro.2017.10.341
Supported by : German Federal Ministry for Economic Affairs and Energy