变压器局部放电光纤超声检测技术及新复用方法

传统的变压器局部放电声波检测技术主要是使用压电陶瓷传感器进行外置式检测,检测效果较差。光纤超声传感器具有绝缘性能好、抗电磁干扰性能优异、尺寸小等优势,可深入变压器内部感知微弱超声信号,这为变压器局部放电检测提供一种全新的解决方案。目前,国内外诸多研究机构已针对于变压器局部放电检测需求研制出各种光纤超声传感器。这些传感器在实验室研究中表现出优异的检测性能,但尚鲜有工程应用。此外,文献报道的光纤超声传感器主要为单点式结构。光纤超声传感器的多路复用问题一直未能得到很好的解决。为此,对现有光纤超声传感器的研究现状进行总结,从基本原理、结构参数、性能指标等方面进行对比分析,为推动光纤超声传感器应用于现场电力变压器局部放电检测提供理论参考。并针对于光纤超声传感器多路复用问题,提出一种基于光频域扫描干涉仪的分布式光纤超声传感系统,该系统能够对变压器局部放电产生的超声波进行多点同步检测,实现放电源定位。

Optical Fiber Ultrasonic Detection Technology for Partial Discharge in Power Transformer and New Multiplexing Method

A lead zirconate titanate sensor installed in an external way is usually used in detection for traditional acoustic emission;however,the detection results are usually poor.The optical fiber ultrasonic sensor has the advantages of good insulation performance,excellent anti-electromagnetic interference performance,and small size,etc..Thus the optical fiber sensor can be installed in the transformer for detecting weak ultrasonic signals,which is a new solution for transformer partial discharge detection.At present,many optical fiber ultrasonic sensors have been developed for partial discharge detection in transformer.These sensors have shown excellent detection performance in laboratory tests,but there are few engineering applications.In addition,the multiplexing of optical fiber ultrasonic sensors is still a challenge.In this paper,the current research situation of optical fiber ultrasonic sensors was summarized.The basic principles,structural parameters and performance indicators of the optical fiber ultrasonic sensors were analyzed.The research results can provide theoretical framework for the application of optical fiber ultrasonic sensors in the partial discharges detection of power transformers.Moreover,for the multiplexing of optical fiber ultrasonic sensors,a distributed fiber-optic ultrasonic sensing system based on optical frequency-domain scanning interferometer was proposed.The experimental results indicate that the ultrasonic signals generated by a partial discharge defect model can be detected simultaneously,and the defect can be located accurately.