Analysis of Typical Acoustic Signal Characteristics of Partial Discharge in 66kV Real-type Transformer

Partial discharge (PD) defects can progressively deteriorate during operation and may even trigger high-energy discharge failures, posing serious threats to the safe operation of transformers. In this study, a partial discharge experimental platform is established using a 66 kV real-type transformer. A floating defect is introduced, and the step-up voltage method is adopted for the experiment. Embedded FBG acoustic sensors are used to record the acoustic signals generated during the PD process. The typical characteristics of the acoustic signals indicate that the FBG (Fiber Bragg Grating) acoustic sensor can effectively monitor the internal PD acoustic signals within the transformer. As the applied voltage increases, both the signal amplitude and the discharge frequency rise, reaching a maximum of 178.21 mV and 6000 times/min near the breakdown stage. In the time domain, sharper spikes appear in the signal, and in the frequency domain, the signal shifts toward the lower frequency band. Phase resolved partial discharge (PRPD) and phase resolved partial discharge severity (PRPS) patterns reveal that as the discharge severity intensifies, the discharge phase width broadens and the duration lengthens.