Vibration-based structural health monitoring of a wind turbine system Part II: Environmental/operational effects on dynamic properties

Research output: Contribution to journalArticle


The second part of these companion papers mainly researches environmental/operational influences on structural dynamic properties under normal operational conditions during two years, in order to extract a statistical based damage-sensitive indicator for health monitoring of a wind turbine system. The correlation analyses between experimental identified frequencies, damping values as well as mode shapes and environmental/operational factors such as rotation speed of blades, wind speed, pitch angle, temperature and nacelle direction are presented. It is observed that the frequency estimates are influenced by the nacelle position, the activation of rotor, the rotation speed of blades and the wind speed as well as the temperature. Regarding to the damping estimates, they are mainly associated with variation of the aerodynamic damping due to the increasing wind speed. Besides, the resonance phenomenon is also observed in higher modes. The harmonic frequencies due to blades passing by tower are found and the corresponding damping value decreases. Moreover, the mode shapes in some modes are strongly affected by the position of the nacelle. Subsequently, two types of simulated damage including the reduction of stiffness in both the rotor blade and the tubular tower are successfully detected by applying the Principal Component Analysis (PCA) based methods to these temperature-sensitive frequency estimates. Comparison of change of the extracted health features indicates that they are more sensitive with the tower damage.


External organisations
  • Federal Institute for Material Research and Testing (BAM) Germany
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Reliability and Maintenance


  • Damage detection, Environmental/operational effects, Modal properties, Novelty analysis, Principal Component Analysis, Structural health monitoring, Vibration, Wind turbine
Original languageEnglish
Pages (from-to)273-290
Number of pages18
JournalEngineering Structures
Publication statusPublished - 2015 Apr 5
Publication categoryResearch
Externally publishedYes