Ice monitoring of a full-scale wind turbine blade using ultrasonic guided waves under varying temperature conditions

Abstract

The icing of wind turbine blades is a common problem in cold climate area. Ice accretion on wind turbines, particularly turbine blades, can cause a variety of problems. The extreme icing may induce full stop of the turbine system. Thus, ice monitoring is one of the important issues for turbine blade icing solutions. The ice coating on the blade surface can change the primary propagation characteristics of the elastic waves. Therefore, Lamb waves are proposed to monitor the ice-forming processes of a full-scale wind turbine blade. Because the varying temperature is a remarkable and inevitably factor during ice monitoring, a principal component analysis (PCA)-based ice monitoring method is proposed to eliminate the temperature effects and is first demonstrated by a segment of the blade in the laboratory. Subsequently, the proposed method is applied on a full-scale blade in the frozen tunnel. The PZT wafers array is arranged to enhance the guided wave signals, and the tuning and attenuation characteristics are investigated on the clear surface of blade without ice. Finally, the PCA-based method is used to identify the ice formation again on both the tip and the middle segments of the full-scale blade under varying temperature conditions. The results indicate that the proposed ultrasonic guided wave combining PCA-based method is efficient and sensitive for ice monitoring of the full-scale wind turbine blade.