Dynamic Detection and Analysis of Foundation Defects of Annular Wind Turbine Based on Solid Elastic Wave Theory

• Published in: Journal of testing and evaluation 2024-11, Vol.52 (6), p.1-17
• Main Authors: Wei, Huan-Wei, Li, Lian-Chun, Song, Peng, Zhu, Jian, Chen, Chao-Wei, Shang, Wen-Tao, Zheng, Xiao
• Format: Article
• Language: English
• ISSN: 0090-3973; 1945-7553
• DOI: 10.1520/JTE20230775

Cracking and separation may occur between the wind turbine foundation ring and the foundation concrete under long-term cyclic wind loads. These severe cracks affect the normal operation of wind turbines. It is necessary to detect the cracks in the foundations before reinforcement treatment. Vibration velocity data are obtained by conducting nondestructive vibration testing on the wind turbine foundation. The theory of solid elastic waves is adopted to analyze the time-domain image, frequency-domain image, time-frequency image, and wavelet energy spectrum. The differences in vibration signals between normal and problematic wind turbines are discussed using this analysis. It is found that the vibration velocity of the normal wind turbine uniformly decays. However, the problematic wind turbine experienced a loss in vibration velocity, with the vibration frequency amplitude being twice that of the normal wind turbine. This indicated that the cracks hindered the attenuation of frequency amplitude. The analysis of time-frequency images showed that the vibration response was delayed, and the wavelet energy was reduced by 5 % for the problematic wind turbine. The cracks were filled with epoxy resin material, and the velocity of the foundation was detected after the reinforcement. The excitation return signal was observed, indicating the reliability of the foundation damage-detection vibration. It was suggested that the concrete foundation cracks absorbed the vibration-generated energy, thus determining the location of cracks. The proposed nondestructive testing method for assessing wind turbine foundations in this study was of great significance for monitoring the operation safety of wind turbines.