大电机定子线棒光纤光栅准分布式测温技术

Quasi-distributed Temperature Measurements of Stator Bars Inside a Large Generators Based on Fiber Bragg Gratings

为了使大型发电机具备内部温度场实时监测能力,将联有多个光纤布拉格光栅(fiber Bragg gratings,FBG)的光纤植入定子线棒中,将光纤光栅置于被关心的温度点,实现了定子线棒温度的准分布式多点测量。植入实验表明,裸FBG很容易在植入过程中损坏,且温度特性易受绝缘材料影响;不锈钢毛细管封装FBG可以抵抗定子线棒加工过程中的高温高压及外力的损害,是一种可行的植入方案。在选择植入位置时,实心铜股线和换位绝缘是能够植入FBG的位置。植入FBG后线棒的温度实验表明,嵌入线棒内部的FBG波长随温度变化的线性度为0.999 66,FBG波长时间响应曲线与对应点热电偶温度时间响应曲线有很好的一致性,具有几乎相同的响应时间。基于光纤光栅的准分布式测温技术实现定子线棒温度的实时测量是可行的。

This paper describes a multiplexed temperature measurement approach to monitor the inner temperature of stator bars in large power generators in real time via use of fiber Bragg gratings （FBG）. By embedding the optical fiber with multiple FBG into stator bars, the quasi-distributed measurement is realized. FBG are embedded at some positions closely related to temperature. Empirical results show that bare FBG are damaged easily, and their temperature features are affected easily by insulation materials. The FBG packaged by stainless steel capillaries can avoid damage from high temperature and pressure and force during being embedded into stator bars. The solid strand and position switching insulation are capable to be embedded FBG. The results of temperature experiments demonstrate that the FBG embedded into stator bars keep good characters. The coefficient between wavelength and temperature is 0.999 66. The wavelength-time response curves of the FBG coincide with temperature-time response curves of the thermocouples at the same position, and FBG sensors have the same response time to corresponding thermocouples. So the conclusion can be drawn that quasi-distributed temperature sensors based on FBG can monitor temperature inside the large power generators in real time.