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. © 2020, High Voltage Engineering Editorial Department of CEPRI. All right reserved.