Research On Winding Performance Evaluation Method Of Distribution Transformer Based On Short Circuit Test

As one of the most important equipment in the power grid,the operation of distribution transformer is directly related to the security and stability of the entire power system.The most important part of the transformer is the winding of the transformer.In the operation process,the transformer may have a short circuit.Under the short circuit impact,the winding may deform or even fail due to the thermal and dynamic stability effect of external short circuit.Transformer winding deformation sometimes occurs immediately after the damage accident,more likely to continue to run for a period of time,and the running time is determined by the deformation of the situation and the performance of the winding itself.The performance of transformer winding determines the service life of the transformer.The performance of transformer winding determines the service life of the transformer.After the short-circuit test of the transformer,it is of great significance to evaluate the performance of transformer winding,improve the quality of transformer products,reduce the occurrence of transformer winding faults,and maintain the safe and stable operation of the power grid accurately,reliably and effectively.The main research contents of this paper are as follows:First,the basic principle of transfer function method is analyzed,and the influence of various forces on transformer after short-circuiting is analyzed.Then,the low-frequency,middle-frequency and high-frequency equivalent parameter model of transformer is established,and the parameters of the model are analyzed and calculated to obtain the low-frequency,middle-frequency and high-frequency equivalent model parameter data of transformer.The equivalent circuit of transformer winding is simulated by NI Multisim software.The transformer is tested by short-circuit impedance method,sweep frequency method and oscillation wave method.By changing the equivalent parameters of transformer winding,the law between the indexes of the three methods and the changes of equivalent parameters of transformer winding is obtained.According to the indexes proposed by the three methods,the performance of transformer windings is evaluated comprehensively by the combination of analytic hierarchy process(AHP)and fuzzy comprehensive evaluation model(FCA),and a transformer quality evaluation system is established.The evaluation results show that this method can effectively get the performance indicators of transformer windings,and then evaluate the performance of transformer windings.