Detection of Winding Strain Faults in Power Transformers Based on Weak Fiber Grating Arrays

This paper proposes a transformer winding strain monitoring method based on weak reflection fiber Bragg grating array (WFBG) and optical frequency domain reflection (OFDR) demodulation technology, aiming to solve the deficiencies of traditional detection methods in dynamic response, spatial resolution and anti-interference ability. Distributed strain measurement is achieved by laying weak grid array sensors on the surface of the transformer winding and combining with the OFDR system. The tensile sensitivities of the prepared WFBGS were 0.617με/pm respectively, and the corresponding fitting metric was greater than 99.6%. The rebound sensitivities were 0.633με/pm respectively, and the corresponding fitting metrics were all greater than 98.7%. The difference degree of strain sensitivity during the stretching and spring back processes is 2.5%, which meets the requirement of built-in strain sensing detection in the transformer windings. Meanwhile, winding strain fault detection was carried out based on the true transformer. The experimental results show that the weak fiber Bragg grating array can effectively identify different types of winding strain faults. This method provides a high-precision and anti-interference solution for the online monitoring of the mechanical state of transformer windings, and has significant engineering value for preventing faults in power equipment.