Analysis of a 110kV Transformer Near-Area Short-Circuit Fault Resulting in Winding Deformation and Management Measures

This paper provides some suggestions for the safe, reliable and economic operation of the transformer by studying and analysing a case in which a 110kV transformer was destabilized due to a short-circuit fault in the proximity of the medium voltage side of the transformer, which resulted in the main transformer destabilisation. Firstly, the real cause of the transformer failure is analysed by detailed analysis of the transformer failure process, test and disassembly verification. In addition, by collecting the detailed structural parameter table of the faulty transformer, and further using the self-developed VIT calibration platform system modelling simulation calculation, the actual ability of the transformer to withstand the short-circuit current is not as good as the theoretical withstand value provided by the manufacturer. Finally, for the operating transformers, passive management measures are proposed in terms of irregular short-circuit resistance calibration, segmented operation of medium and low-voltage busbars, neutral point addition of small reactance grounding, addition of current-limiting reactors, and return to the factory (on-site) for overhaul; for the non-networked transformers, proactive management recommendations are proposed in terms of quality control in advance of the network entry, design of the transformer, raw material selection, and requirements of the manufacturing process.