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

TY - JOUR

T1 - Vibration-based structural health monitoring of a wind turbine system Part II

T2 - Environmental/operational effects on dynamic properties

AU - Hu, Wei Hua

AU - Thöns, Sebastian

AU - Rohrmann, Rolf Günter

AU - Said, Samir

AU - Rücker, Werner

PY - 2015/4/5

Y1 - 2015/4/5

N2 - 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.

AB - 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.

KW - Damage detection

KW - Environmental/operational effects

KW - Modal properties

KW - Novelty analysis

KW - Principal Component Analysis

KW - Structural health monitoring

KW - Vibration

KW - Wind turbine

U2 - 10.1016/j.engstruct.2014.12.035

DO - 10.1016/j.engstruct.2014.12.035

M3 - Article

AN - SCOPUS:84925182367

VL - 89

SP - 273

EP - 290

JO - Engineering Structures

JF - Engineering Structures

SN - 0141-0296

ER -