Analysis of Transformer Tank Deformation and Rupture, Part 1: Proposal of Analysis Method

In order to realize the evaluation of the oil tank deformation and rupture of oil-filled transformer under the internal short-circuit arc fault, in this paper the difference of the short-circuit current faced by the converter transformers on both sides is analyzed by comparing the short-circuit current faced by the equipment on the sending end side and the receiving end side of the DC transmission under different power supply conditions. It is demonstrated that the converter transformers faces more stringent short-circuit current conditions on the sending end, and higher risk of oil tank deformation and rupture. Moreover, considering the strong correlation between the severity of the consequences caused by internal arc faults of oil-filled equipment and the short-circuit current faced, by summarizing the fault cases of oil-filled equipment, including converter transformers, AC transformers, generator step-up transformers, shunt reactors, and based on the analysis of the evaluation method in CIGRE A2.33 technical report, combined with factors such as short-circuit current, arc short circuit duration, and oil volume, a reasonable analysis and evaluation method for the oil tank deformation and rupture of oil-filled equipment and the recommended evaluation criterion are proposed. When the recommended evaluation coefficient K>1.15, it is considered that tank of oil-filled equipment does not have the ability to withstand the internal large arc impact, which provides a technical means for fault analysis and engineering application evaluation.