LAUSR

With the increasing demand for electricity, overheating has gradually become a common problem for power transformers. However, the imperfect traditional monitoring method fails to detect the whole transformer in real time, which affects the safe and economical operation of the transformer. This paper was the first research utilizing a distributed optical fiber sensing system inside a running 35 kV power transformer to realize the persistent temperature monitoring of the full region. The detection accuracy of the designed winding composite sensors was also proven feasible for actual monitoring by temperature-rise tests. The hotspots were persistently traced, fluctuating at 83 %~88 %, 84 %~89 %, and 85 %~90 % of the high voltage winding height for phase A, B, and C of the 35 KV three-phase transformer, respectively. Moreover, there are multiple typical models proposed by scientists to delineate the thermodynamic behaviors of power transformers, and the hottest-spot temperature (HST) could be visualized precisely through them. In the article, the construction of four models (IEC, Swift, Susa, and IEEE models) and their comparison with the HST data from the optical fiber sensor were presented, which provided a scientific basis for seeking superior thermodynamic models. According to the evaluation of the results, the Susa model was eventually selected, which could better describe the dynamic thermal behaviors of power transformers. (RMSE was 3.0776).