Design Of The WTG Blades' Stress Testing System

Wind power generation is a technology that can convert the wind energy into electrical energy by use of electromechanical energy conversion device. Once the wind blows the blades, then the blades drive the generator, and the generator in the end generate the electrical energy. During this progress, the blades are the most important that absorbing the mechanical energy directly. When the wind wheel rotates, the blades will be under stress by centrifugal force and aerodynamic force. Blades can be curved by the aerodynamic force, and centrifugal force is a pulling force of the blade. Once the wind speed is higher than the rated wind speed, aerodynamic force will exceed the capacity of blades and damage them. Therefore, when the wind wheel rotates, the stress of the blades must be tested in order to protect the normal operation of generating units.Above all, the FBG sensor is chosen to measure the blades'stress, in order to solve the problems:the temperature of the WTGS'operating circumstance is too below to work for the sensor, the sensor is easy to be disturbed by electromagnetic interference and so on. Besides, the fundamentals of FBG sensor is studied, and the demodulation techniques of the FBG sensor is researched and the F-P filter demodulation techniques based on the DSP is chosen in the end.Secondly, the optical equipments of the demodulation system are chosen. Besides, the hardware design mainly includes:power circuit of the DSP, AD circuit, DA circuit, RS232 SCI circuit, photoelectric detector circuit and so on. And the software design mainly includes:LabVIEW display program, communication program and the DSP sawtooth program and so on.Finally, in order to test and verify the sensor features, an iron support stand of stress measured equipment is designed. Besides, the stress to be measured is provided by the weights. The sensor wave is gathered by the signal collect circuit and displayed, saved in the LabVIEW. Meanwhile, the gathered sensor wave is commuted as stress in the DSP, further more, the stress is commuted as mass. The measurement result shows:this demodulation system can precisely measure the stress offered by the weights, and proves this design is correct.