基于Sagnac干涉仪的多点局部放电检测系统

Multi-point partial discharge detection system based on Sagnac interferometer

提出了一种基于光纤Sagnac干涉仪用于多点局部放电超声检测的光纤传感系统。该超声检测系统由光源、单模光纤延迟线、光纤耦合器、相位调制器、偏振控制器和对比度为1的光纤Sagnac干涉仪组成。首先介绍了传感系统的超声检测的原理,然后搭建了模拟局部放电超声实验平台,利用Nd∶YAG激光器照射钢板激发出的表面波和高频声源,针对局部放电超声在钢板和变压绝缘油中的传播情况进行了实验。实验结果证明了使用该系统用于局部放电超声检测的有效性,在100 kHz~200 kHz频率范围内,信噪比可达40 dB以上,同时实验验证了该Sagnac传感器对局部放电超声的多点检测能力。该光纤超声检测系统结构简单,频率响应高,成本低廉在局部放电等领域有着巨大潜力。

In this paper,a fiber optic sensing system based on fiber optic Sagnac interferometer is proposed for ultrasonic detection of multi-point partial discharge.The detection system consists of a light source,a single-mode fiber delay line,a fiber coupler,a phase modulator,a polarization controller and a fiber Sagnac interferometer with a contrast ratio of 1.Firstly,the principle of ultrasonic detection of the sensor system is introduced,and then an ultrasonic experimental platform for simulating partial discharge is built.Experiments on the propagation of partial discharge ultrasound in steel plates and transformer insulating oil using surface waves excited by irradiation of steel plates with a Nd∶YAG laser and a high-frequency acoustic source.The experimental results prove the effectiveness of using this system for partial discharge ultrasonic detection,with a signal-to-noise ratio of more than 40dB in the frequency range of 100 kHz-200 kHz.At the same time,the experiments validate the multi-point detection ability of the Sagnac sensor for partial discharge ultrasonic.The optical fiber ultrasonic detection system has a simple structure,high frequency response and low cost,and has great potential in the fields of partial discharge.