DFB-FL/Interferometer Composite Partial Discharge Ultrasonic Detection System

The ultrasonic detection method for optical fiber partial discharge has good adaptability and application prospects in the partial discharge testing of power systems due to its advantages such as high detection sensitivity, small size, and strong anti-electromagnetic interference capability. To address the limitations of the single distributed feedback type fiber laser sensor (DFB-FL), such as limited measurement range, strong feedback noise in long-distance applications, and phase noise during transmission, while improving the measurement sensitivity of the interferometer structure, a sensing structure combining DFB-FL and interferometer was designed. By using a polymer with high viscosity, low Young’s modulus, and large Poisson’s ratio as the coupling medium for DFB-FL, the strain from the measured object is as much as possible converted into the axial strain acting on DFB-FL, thereby increasing the sensing sensitivity of DFB-FL and improving the composite sensing structure. A simulation test platform for detecting partial discharge in 220kv XLPE cable air gaps was built, and this testing system was applied to measure the simulated partial discharge signals in the cable air gaps, verifying that the testing system has strong sensitivity.