Research on 35kV Transformer Distributed Temperature Sensing System Based on Optical Fiber Sensing

Accurate detection of transformer winding and hot spot temperature directly affects the stability and economy of the transformer. To achieve accurate and real-time monitoring of winding temperature distribution, a distributed temperature sensing system for transformers based on fiber optic sensing has been developed. A 35kV., 200kVA three-phase double winding transformer was installed with temperature sensing fibers. A total of 12 sensing fibers were set up. The fiber is led out through a custom flange on the upper side of the tank wall. During the temperature rise test, ROTDR was used to monitor the temperature distribution, with a sampling resolution of 0.8m along the fiber. A total of 3032 sampling points were obtained and the 3D temperature distribution of the winding was obtained. Comparing the distributed measurement results with the calculated hot-spot temperature rise based on IEC60076-2, the result show that the temperature distribution of the winding and the hot spot temperature can be obtained more accurately through the sensing fiber laid on the winding and the ROTDR technology, so that the accurate estimation of the load capacity of the transformer and the timely detection of overheating faults can be achieved.