Real-time monitoring system for multi-MW scale wind blades using FBG sensors

Measured by distributed fiber Bragg grating (FBG) sensors, an application and strain analysis of real-time structural health monitoring system for muti-MW scale wind blades during the service process has been established and investigated. The experiments of the multi-MW scale wind turbine were performed at the top of the hill, near the sea and the FBG sensors were mounted at various locations on the internal surfaces of the rotating blades. The feasibility and effectiveness of the system were validated by continuously transmitting the optical signals between the FBG demodulator and the sensors. The internal dynamic strain of the blades during the environmental fatigue loadings were monitored, valuated and given crash alert with FBG sensors through the results of preliminary field tests. Through Hilbert-Huang transform (HHT), the strain data were decomposed into a series of intrinsic mode functions (IMF) and residual component by the empirical mode decomposition (EMD) method under different frequencies.