Highly Sensitive Micro-Optical Fiber Probe for Power Transformer Partial Discharge Detection

Partial discharge (PD) detection is crucial for ensuring the safe operation of power transformers. Optical fiber sensors (OFS), with advantages of electromagnetic interference (EMI) resistance, inherent safety, and suitability for embedded installation, demonstrate significant promise for PD detection. The micro-optical fiber probe (MOFP) with compact size (diameter 10 mm, height 4.9 mm) is proposed, which ensures sensitivity while offering the convenience and versatility required for embedded installation. The implementation of the heterodyne interferometric demodulation topology is employed to enhance stability, while the optimization of system parameter combinations leads to an improvement in the detection signal-tonoise ratio (SNR) by 24.7 dB. In the lab, the developed OFS achieves a 62% and 223.3% improvement in the SNR for detecting ultrasonic signals propagating in solid and in oil, respectively, compared to the typical PZT (R15α). In the field, the OFS was effectively installed inside the power transformer and detected PD ultrasonic signals, addressing the issues of EMI with HFCT and the installation difficulty and low sensitivity of PZT. The results substantiate that the developed OFS provides a novel, reliable and effective approach for PD detection in power transformers.