DFB-FL Applied in the Liquid-Solid Composite Dielectric for Ultra-High Sensitive Partial Discharge Acoustic Emission Detection
Jixian Qiao, Weichao Zhang, Qichao Chen, Xuan Wang, Hong Zhao
Abstract
The traditional fiber optic acoustic emission (AE) sensor, used to detect the partial discharge (PD) in the liquid-solid composite dielectric such as oil-immersed transformers, is not satisfactory in engineering applications due to the limitation of sensitivity and sensor size. This work proposes that the distributed feedback fiber laser (DFB-FL), benefiting from its tiny size and ultra-high sensitivity, is a better choice for PD AE detection. We build the PD AE detection system using erbium-ytterbium co-doped (Er-Yb-co-doped) DFB-FL, with suitable photoelectric components to design the demodulation system and intensity noise of DFB-FL as an index. Noise analysis shows that the average noise amplitude of the system is reduced by 91.67% after digital filtering technology and pump laser power regulation technology. We also use an 80 kVA oil-immersed transformer winding structure to construct a liquid-solid composite dielectric PD AE detection platform. Moreover, experiment results in different pump power show that the DFB-FL PD AE detection system can effectively detect the PD AE signal in the environment with sizeable acoustic impedance. The peak-to-peak value of its response is 31.36 times larger than the background noise and 637% higher than piezoelectric transducer sensors (PZT).