Ultrasonic signals will be generated when partial discharge occurs in internal insulation faults in large oil immersed power transformers: because the ultrasonic signal has strong anti-interference ability and has no direct electromagnetic contact with the equipment, it is widely used in transformer fault detection and positioning. In this paper, the finite element method (FEM) is used to simulate the ultrasonic signal in a 35 kV power transformer. The influence of transformer case on ultrasonic signal propagation is considered, and the propagation law of the ultrasonic signal inside the transformer is obtained. Fabry–Pérot (F–P) fibre acoustic sensors with a centre frequency of 28 kHz were fabricated. A partial discharge detection test was carried out in a 35 kV transformer winding model using the F–P sensors. The test results show that the ultrasonic waveform detected by the F–P sensors are in good agreement with the simulation results, and the propagation of the ultrasonic wave inside the transformer is verified. It lays a foundation for detecting and locating PDs in power transformer by F–P acoustic sensors.

中文翻译：

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电力变压器模型中局部放电超声波信号传播的有限元仿真和测试验证

大型油浸式电力变压器内部绝缘故障发生局部放电时会产生超声波信号：由于超声波信号抗干扰能力强，与设备无直接电磁接触，被广泛应用于变压器故障检测和定位. 在本文中，有限元法（FEM）用于模拟35 kV电力变压器中的超声波信号。考虑了变压器外壳对超声波信号传播的影响，得到了超声波信号在变压器内部的传播规律。制造了中心频率为 28 kHz 的 Fabry-Pérot (F-P) 光纤声学传感器。使用 F-P 传感器在 35 kV 变压器绕组模型中进行了局部放电检测测试。测试结果表明，F-P传感器检测到的超声波波形与仿真结果吻合较好，验证了超声波在变压器内部的传播。为利用F-P声传感器检测和定位电力变压器中的局部放电奠定了基础。