Fiber Optic Acoustic Sensor Based on SMS Structure With Thin Polymer Diaphragm for Partial Discharge Detection

L. G. Pavan Kumar Chaganti,Muhammad Yusof Mohd Noor,Mohamed Afendi Mohamed Piah,Asrul Izam Azmi,Mohd Hafizi Ahmad

doi:10.1109/access.2020.3031578

L. G. Pavan Kumar Chaganti, Muhammad Yusof Mohd Noor + Show 3 more

Open Access

https://doi.org/10.1109/access.2020.3031578

Copy DOI

Abstract

This paper proposes a fiber optic acoustic sensor (FOAS) based on a single-mode fiber - multimode fiber - single-mode fiber (SMS) structure attached to a thin polymer film used as a diaphragm. The diaphragm was specially developed to enhance the sensitivity towards the acoustic pressure-wave resulted from the partial discharge (PD) events. The sensitivity and signal-to-noise ratio (SNR) characterizations of the FOAS without and with a thin polymer film were performed. Both time-resolved and phase-resolved partial discharge (PRPD) patterns measurements were carried out in air and oil media. The experiment was conducted with three-electrodes using FOAS in conjunction with the conventional PD measurement as per IEC 60270 standard. The sensor achieved a sensitivity up to -31.21 dBm and -30.8 (0 dBm is defined as 1V/μBar) using broadband and tunable light source, respectively. The discharge characteristics pattern of FOAS was verified with IEC 60270 standard, and the patterns of FOAS resembled IEC 60270 standard. The proposed FOAS was capable for detecting the PD using both broadband and tunable laser lights. The use of the thin polymer film had a significant impact on the acoustic sensitivity. With the simple, low-cost design structure and free from electromagnetic interference, FOAS is found to be suitable as an in-situ sensor for detecting the acoustic signals of partial discharge and can be utilized inside the transformer.

Highlights

The power transformer and switchgear are the key equipment in the power systems and traction systems
To choose which type of light source is preferable for the phase-resolved partial discharge (PRPD) measurement, the experiment performed for 60 minutes using both BBS and TLS are shown in Fig. 13 under the similar condition of voltage
The investigation concludes a significant impact of the thin polymer film in SMS structure for the acoustic pressure of partial discharge (PD) detection

Summary

INTRODUCTION

The power transformer and switchgear are the key equipment in the power systems and traction systems. Li et al demonstrated that a single-mode-multimode (SMS) structure strain sensors were two times more sensitive than an FBG [26] Due to these advantages, several researchers used SMS in low-frequency acoustic sensing for a frequency range below 2 kHz [27]–[29]. Our FOAS achieved SNR around 60 dB at 40 kHz. The research study is carried out using FOAS without and with a thin-film diaphragm to detect the acoustic signal both in air and oil media and lengthy its practice to the power transformer. The interference caused by the acoustic vibration acting on the MMF results in the phase alteration of the light propagating in the fiber, which in turn measured as the intensity at output SMF.

FOAS WITHOUT POLYMER FILM FABRICATION

CONCLUSION