基于激光多普勒测振的气体绝缘输电线路机械缺陷非接触检测技术与应用

Application of Non-Contact Vibration Detection For Gas Insulated Transmission Line via Laser Doppler Vibrometer Technique

提出一种基于激光多普勒测振(LDV)的气体绝缘输电线路(GIL)非接触振动测量方法。通过GIL的瞬态电磁-结构多场耦合有限元建模和原型物理试验获取正常和缺陷下的振动频率和幅值特征,并确定测点位置与LDV系统的主要参数。设计包含窄线宽激光器、收发一体光学天线、声光调制器和平衡探测器的1550 nm全光纤光路模块,实现了对包含对象运动信息的光学拍频信号检测。开发了基于数字正交和微分交叉相乘算法的振动信号解调方案,实现了0.5~20 m探测范围、50 Hz~20 kHz机械振动信号的非接触测量。所研制的系统成功应用于GIL原型平台测试和现场GIL巡检,能够有效克服接触式加速度传感器测点固定困难、检测效率和准确度低下的不足,实现了长距离GIL设备的非接触振动测量。

In this paper,a noncontact vibration detection method for gas insulated line(GIL)based on laser Doppler vibrometer(LDV)technology is proposed.First,vibration frequency and amplitude distribution under normal and defect conditions are obtained by transient electromagneticstructural coupled field finite element modeling and physical experiments.Besides measuring points on GIL surface and parameters of LDV system are also confirmed.The 1550 nm fiber optical path component including narrow linewidth laser,optical transceiver,acoustooptic modulator(AOM)and balanced detector is designed,and the optical beat signal which contains object movement information is successfully obtained.Vibration signal demodulation scheme based on digital orthogonal and differential cross multiplication algorithm is developed.The mechanical vibration signals within frequency range 50 Hz‒20 kHz between 0.5‒20 m distance are acquired by proposed system.The developed system has been successfully applied to GIL prototype platform testing and onsite GIL inspections,effectively overcoming the shortcomings of contactbased accelerometers,such as installation difficulties,low detection efficiency,and poor accuracy.This has enabled noncontact vibration measurement for longdistance GIL equipment.