AUTHOR=Wang Junchao , Tong Zhixiang , Zhang Kun , Liu Yaqi , Deng Xiangli , Tu Hang 

TITLE=Research on transformer early fault diagnosis based on fiber - optic leakage magnetic field measurement

JOURNAL=Frontiers in Energy Research

VOLUME=Volume 13 - 2025

YEAR=2025

URL=https://www.frontiersin.org/journals/energy-research/articles/10.3389/fenrg.2025.1650577

DOI=10.3389/fenrg.2025.1650577

ISSN=2296-598X

ABSTRACT=When a severe fault occurs within a transformer, the fault current escalates rapidly, making it challenging for differential protection systems to promptly isolate the faulty transformer. This delay can lead to catastrophic accidents, such as explosive combustion. To address this issue, this study proposes a novel differential protection device based on leakage magnetic field characteristics. The device accurately detects transformer winding deformation, arc-type faults, and inter-turn faults during the early stages of transformer faults, thereby preventing severe accidents. By analyzing several early transformer fault cases, this study proposes leveraging the symmetry characteristics of the leakage magnetic field to identify early faults. A fiber-optic sensor, utilizing the Faraday magneto-optical effect, is developed to measure leakage magnetic field characteristics. Based on this, a differential protection scheme incorporating steady-state and transient leakage magnetic field quantities is proposed to identify winding deformation and inter-turn faults. A prototype of the protection device has been developed, successfully passing static and dynamic simulation tests, and is slated for deployment in field operations.