Vibration Monitoring of Wind Turbine Blade using Fiber Bragg Grating

Abstract

Rapid growth in generating power from wind turbines led to application of long laminated composite blades. However, as the length of blades increases, the risk of failure due to excessive vibration increases. Therefore, a reliable wind power generator requires an efficient and accurate, yet economical structural health monitoring system to detect vibration and apply a reliable control to prevent from unpredicted failure. This paper presents an optimal, low cost and continuous vibration monitoring system for laminated composite blades using Fiber Bragg Grating (FBG). Utilizing a layerwise displacement theory, the Finite Element (FEM) model has been developed for the wind turbine blade. The optomechanical relations between strains and FBG wavelength shift have been presented to study the dynamic of a wind turbine blade. The reflected spectrum caused by modal displacement, interrogated by WDM method has been studied for vibration control. Numerical examples have been presented to compare the FEM and FBG results which show a very good agreement for the first 3 vibration modes.