Condition Monitoring and Damage Location of Wind Turbine Blades by Frequency Response Transmissibility Analysis

Incipient defects occurring in long wind turbine (WT) blades are difficult to detect using the existing condition monitoring (CM) techniques. To tackle this issue, a new WT blade CM method is studied in this paper with the aid of the concept of transmissibility of frequency response functions. Different from the existing CM techniques that judge the health condition of a blade by interpreting individual CM signals, the proposed method jointly utilizes the CM signals measured by a number of neighboring sensors. This offers the proposed technique a unique capability of both damage detection and location. The proposed technique has been experimentally verified by using the real CM data collected during the fatigue and static tests of a full-scale WT blade. The experiment has shown that the new technique is effective not only in damage detection but also in damage location when either fiber Bragg grating strain gauges or accelerometers are used for data acquisition.