530 / 2022-03-28 18:09:51

Analysis of a typical auto-reclosing short-circuit fault for power transformer

power transformer,short-circuit fault,auto-reclosing,winding deformation

The safe and stable operation of the power transformer is an important guarantee for the reliable power supply of the system. However, transformers are facing a serious threat of short-circuit current shocks during operation, especially under short-term, multiple continuous short-circuit current, the mechanical stability of transformer windings may have significantly deteriorated. In this paper, a typical 220 kV transformer reclosing short-circuit event is analyzed in detail. Based on the analysis of fault recordings and protective actions, the transformer windings are diagnosed to be deformed and damaged by the results of dissolved gas analysis in transformer oil, DC resistance, and insulation resistance tests. In order to verify the diagnostic analysis results, the transformer is checked and analyzed by factory disassembly. It is found that the transformer has axial wavy distortion in the medium-voltage winding, serious radial distortion in the regulator-voltage and high-voltage windings. The diagnostic analysis results are verified and the fault development process is analyzed. At last, the preventive measures against such accidents are put forward.