An Improved Radial Buckling Analysis Method and Test Investigation for Power Transformer under Short Circuit Impact

The inner winding of the power transformer is subjected to uniform compressive stress in the radial direction during the short circuit, which makes circular radial stability a crucial component of reliability. At present, the radial stability evaluation system lacks the sufficient state characteristic judgment quantity considering the manufacturing devia-tions and assembly gaps, which makes the design and cal-culation of the transformer have significant variation devia-tion and seriously endangers the operation safety of the equipment. This paper proposes an improved radial buck-ling analysis method (IRBAM) to investigate the circular radial stability of inner winding. The IRBAM is implement-ed by defining two characteristic parameters, equivalent flexibility and manufacturing deviation (MD). Besides, the buckling judgment method of the relative change ratio of impedance (RCRI) is proposed as a condition for ending the test. The destructive short-circuit tested transformer, with the rated power of 50MVA and the high-voltage (HV) rated voltage of 110 kV, is designed. Then, 72 cumulative short-circuit tests are performed until impedance exceeds the permissible value based on the judgment. It is verified that IRBAM can effectively match the failure mode of the transformer windings by comparing the experimental phe-nomena and calculation results.