Modeling and Multi-Physics Field Analysis if Transformer Partial Discharge Detection Using PMUTS-Based Devices

Ultrasonic detection comprises a critical methodology for non-intrusive monitoring and diagnosis of partial discharges (PD) in power transformers. However, the state-of-the-art on ultrasonic signal propagation from internal PD sources generally relies on simplified models and single PD sources. Conventional PZT-based ultrasonic transducers are limited to PD detection because of their large size, high power consumption, impedance mismatch, and low receiving sensitivity. This study demonstrates the modeling and analysis of ultrasonic PD detection using piezoelectric micromachined ultrasonic transducers (PMUTs). Dual PD sources are implemented, and the sound pressure distribution is deeply analyzed. Nine PMUTs chips receive the ultrasonic signals; propagation paths and peak sound pressures are characterized. Five chips exhibited propagation time relative errors within 1.68%, indicating direct wave reception. The remaining four showed errors between 1.85% and 5.51%, consistent with indirect waves. The propagation distance of the indirect wave on the steel plate was also calculated. This study establishes the foundation for PD detection by PMUTs-based devices.