Research on Transformer Oil Condition Diagnosis Technology Based on Multi-Frequency Ultrasonic Detection

Oil-paper insulation is an important form of insulation in transformers. Under external stresses such as discharge and overheating, transformer oil may gradually deteriorate, leading to changes in its physical and chemical properties. In this paper, a multi-frequency diagnosis system for transformer oil insulation status is designed based on multi-frequency ultrasonic detection technology, with the frequency range of ultrasonic waves between 200-1000 kHz. The diagnosis of transformer oil status is achieved by comparing the attenuation spectra of multi-frequency ultrasonic signals received by the receiving sensor and transmitted by the transmitting sensor. To analyze the characteristics of the attenuation spectra of multi-frequency ultrasonic signals of transformer oil with different degrees of aging, a comprehensive experimental platform is established. This platform combines the pulse current method and the dissolved gas analysis method to study the ultrasonic attenuation spectra characteristics of transformer oil in the initiation, development, and pre-breakdown stages of discharge. It provides experimental basis for subsequent theoretical analysis and diagnosis of transformer oil insulation status.