无源光网络(PON)光层监测技术

讨论了基于OTDR的PON网络测试,分析其局限和改进技术。针对OTDR-based技术的缺陷,研究了非OTDR监测技术,重点是布里渊频率移位和基于光编码的反射测试等,讨论了相关技术的特点和应用前景。

基于分布式光纤传感的变压器绕组变形定位技术

将分布式光纤传感技术应用于变压器突发短路试验有助于绕组变形的准确定位。研制了1台10k V油浸式变压器模型并进行了30%~70%短路负载电流下的突发短路试验,基于布里渊散射的光时域反射技术获得了低压b相绕组的发热规律和形变规律。结果表明,30%~60%短路负载电流下绕组产生一定热效应,布里渊频率从2.585MHz正向移动到12.166MHz,温升从1.62K增加到8.34K,该电流范围内绕组几乎无变形;70%短路负载电流时,布里渊频率出现负向移动,并沿绕组长度方向周期性变化,应变最大值为-540με。最后,变压器拆解验证了分析的准确性。研究结论为变压器绕组变形的监测提供了新思路。

基于BOTDA的OPGW应变性能研究

为研究长期运行光纤复合架空地线(OPGW)的应变性能,使用高精度的分布式光纤传感监测设备布里渊光时域分析仪(BOTDA)对新缆和不同覆冰环境下的旧缆进行应变监测,对比分析了OPGW光缆内光纤的布里渊频率在长期外界环境作用下的变化。试验结果表明,运行时间和覆冰等级是影响OPGW光缆内光纤应变性能的主要因素。

SELECTION OF BRILLOUIN SHIFT DISCRIMINATOR FOR BRILLOUIN LIDAR

For the measurement of vertical profiles of sound speed in the sea using laser excited Brillouin scattering, a high resolution measurement of Brillouin frequency shift is required. In this work, a molecular absorption cell was selected as the frequency shift discriminator and several kinds of absorption gases were tried. It was found that the strong line (#1095) of 127 I 2 at 18783.3297 cm -1 and two absorption lines of 129 I 2 located at the two sides of the #1095 line of 127 I 2 could be used as frequency shift discriminator to detect the changes of the Brillouin frequency shift. This selection is the best one within the range from 532.0131 nm to 532.5154 nm. But it is not perfect and there is a lot of work to do before its practical application.