非本征F-P局部放电光纤传感器设计及灵敏度分析

Extrinsic F-P fiber optic sensor design for partial discharge detection and sensitivity analysis

为解决超声波法检测电力设备局部放电灵敏度低问题,提出一种采用石英膜片的全电介质结构的光纤法-珀超声传感器设计方法。为获得适于局放检测频响特性的法-珀传感器,根据弹性力学原理分析法-珀传感器固有频率随膜片尺寸参数变化规律,利用ANSYS有限元仿真方法设计3种不同结构尺寸的法-珀传感器。在绝缘油箱中采用信号发生器驱动压电陶瓷传感器发射50kHz^250kHz超声波,获得F-P传感器的幅频特性曲线。F-P1~F-P3对板-板电极局放声信号检测实验表明,设计传感器一阶固有频率在150kHz处可有效检测局放,且相同固有频率下F-P传感器灵敏度随膜片厚度减小而显著提高。相同结构参数下腔长为130μm和100μm的F-P传感器检测灵敏度前者是后者的2.47倍,实验结果表明增加F-P腔长可提高传感器局放检测灵敏度。

To solve the problem of low sensitivity when using ultrasonic wave method to detect partial discharge(PD)in power equipment,a dielectric fiber Fabry-Perot(F-P)acoustic sensor with quartz membrane was designed.For suitable frequency response characteristics of F-P sensor,the natural frequency of F-P sensor changed with diaphragm size was analyzed based on the theory of elasticity,and 3F-P sensors with different sizes were designed using ANSYS finite element analysis method.The ultrasound waves from 50 kHz to 250 kHz were generated from piezoelectric transducer(PZT)driven by signal generator in insulating oil tank.The ul-trasound waves were detected by 3F-P sensors to get the amplitude-frequency characteristic curves.The experiment of plate-plate PD detection by F-P1~F-P3 shows that the F-P sensors with the first natural frequency of 150 kHz could detect PD signals effectively,and the sensitivity can be significantly enhanced with the decreasing diaphragm thickness under the same natural frequency.The F-P sensor sensitivity with the cavity length of 130μm is 2.47 times of that of the F-P sensor with 100μm cavity length.The results show that the PD detection sensitivity of F-P sensor can be enhanced by increasing the F-P cavity length.