Remote Measurements and Vibration Analysis of Existing Wind Turbines

• Published in: Journal of testing and evaluation 2019-05, Vol.47 (3), p.2193-2206
• Main Authors: Chiang, Chih-Hung, Hsu, Keng-Tsang, Yu, Chih-Peng, Cheng, Chia-Chi, Pan, Jie-Zhen
• Format: Article
• Language: English
• ISSN: 0090-3973; 1945-7553
• DOI: 10.1520/JTE20180025

Extreme weather is a constant threat to the service of a wind turbine, as it may cause damage to the rotor blades or even lead to the collapse of a supporting tower. A change in the dominant frequency may indicate a deviation from the design of the stiffness of the turbine-tower system. Dynamic measurements of the lateral displacement of four 2-MW wind turbines of the same model have been obtained using a ground-based microwave interferometer. Vibration analysis, including frequency domain decomposition and reassigned spectrograms, is undertaken to evaluate the frequency contents of a turbine-tower system. Dominant frequency, along with other peak frequencies, is readily identified when the rotor is stopped or operated at low to medium speed. Dynamic characteristics found in the vibration analysis are closely examined to identify indicators of structural deficiency in the supporting tower of a wind turbine. The results are promising as they combine noncontact dynamic measurements and vibration analysis for the condition assessment of wind turbine tower systems. Preliminary numerical results also indicate possible further enhancement of the proposed vibration analysis, using the relation curve that highlights the discrepancy percentage of normalized deflections with respect to the change in stiffness of the supporting tower of a wind turbine.