Research On Winding Deformation And Short Circuit Strength Of Power Transformer

The transformer is an important device in the power industry,and its operation has an important impact on the stability and reliability of the entire power system.With the rapid development of the national economy and the need for large-scale construction of the power industry,it is particularly important whether power transformers have good reliability in various application scenarios.In practice,the transformer will inevitably be damaged by the short-circuit electromagnetic force,and cumulative deformation will occur under multiple short-circuit conditions,which seriously threatens the stable operation of the transformer.Therefore,studying the winding deformation and short-circuit strength of power transformers under multiple short-circuit conditions has an important role in avoiding major losses caused by serious faults during the operation of the transformer.First,a two-dimensional finite element model of the transformer was established in ANSYS.The internal leakage magnetic field and the electromagnetic force on the windings when the transformer was short-circuited were studied,and the distribution of the leakage magnetic field and electromagnetic force was analyzed.Then,the transformer deformation and short-circuit strength during a three-phase short circuit are analyzed.Based on the mechanical characteristics of elastoplastic materials,an elastoplastic simulation model of the transformer winding is proposed.The elastoplastic model of the transformer winding is simulated using the magnetic-structure coupling calculation method.The electromagnetic force,deformation,stress and strain in the short circuit process are analyzed.The strength of the winding was analyzed based on the winding strength check method.At the same time,the effect of temperature on the plastic deformation during the short circuit was analyzed.Finally,the winding deformation and short-circuit strength of the transformer during multiple short circuits are analyzed.Based on elasto-plastic mechanics,a method for calculating the cumulative plastic deformation and winding deformation of the transformer during multiple short circuits is deduced,and the influence of the cumulative plastic deformation generated on the winding strength during multiple short circuits is analyzed.According to the calculation results,this paper analyzed the characteristics of the cumulative deformation of the winding under different types of short-circuit currents,and proposed a method for verifying the winding short-circuit strength during multiple short circuits based on the cumulative amount of plastic deformation of the winding.This paper analyzed the effect on the cumulative winding deformation and winding strength at different temperatures.