Single Arm Optical Fiber Interferometer Technology for Partial Discharge Acoustic Detection

The fiber optic interferometer, an instrument for partial discharge (PD) acoustic wave detection, is currently receiving much attention. Due to the high sensitivity, the dual-arm fiber optic interferometers have been used in the field of PD detection for a long time. However, the long-distance guided fiber structure of the dual-arm interferometer is prone to coupling environmental noise, and there are difficulties in matching the optical path difference which is used to generate interference. This article elaborates on two types of single-arm interferometric fiber optic technology for PD acoustic sensing. First, it summarizes the work in recent years on extrinsic fiber Fabry-Perot (F-P) interferometer based on microelectro-mechanical system (MEMS). Meanwhile, the distributed feedback fiber laser (DFB-FL) sensing technology is mainly demonstrated to detect PD acoustic wave signals. Noise suppression is the most important problem for DFB-FL PD measurement. This article presents the mechanism of relaxation oscillation and self-pulse oscillation in DFB-FL, and a theoretical model is constructed. The adjustment of laser parameters is presented to suppress the oscillation noise. Then, composite cavity reflection model is equivalent to Rayleigh scattering from fiber to control reflection noise interference. Furthermore, demodulation method with low-frequency drift noise suppression is proposed to promote PD detection sensitivity.