Research on a New PD Detection Sensor in Transformer Oil Tank Seam

The detection of partial discharge (PD) is essential for the monitoring of transformer conditions. Especially PD signals have unique propagation characteristics within the transformer tank seam, this study aims to develop a novel PD detection sensor based on these propagation characteristics. In this article, the influence of three parameters on the propagation characteristics has been investigated, and it demonstrates that the electric field strength is higher in the tank seam compared with the outer space. In addition, to define the sensor design index, the frequency domain and polarization characteristics of typical defect discharge signals in the seam have been simulated and analyzed. Based on the investigation results, a ultra-wideband (UWB) monopole PD sensor has been designed, which can be installed in the oil tank seam. Finally, the actual sensitivity of the sensor has been tested and compared with the traditional Bow-tie antenna, it reveals that the signal strength detected by the seam sensor is 2.3–3.9 times greater than that of the Bow-tie antenna for four typical defects.