Análise e validação experimental de um modelo de transformador de potência para estudos de transitórios eletromagnéticos de alta frequência

Abstract

The present study introduces a methodology for constructing a computational model of power transformers within the scope of high-frequency electromagnetic transients studies. These transient events are investigated as potential causes of internal failures in power transformers, stemming from both the occurrence of internal overvoltages and dielectric failures between winding layers. Representing transformers through models allows for simulating situations relevant to the voltage distribution across the equipment windings. To this end, techniques for analytically determining transformer parameters are presented. The construction of the electrical circuit of the proposed model makes use of structured descriptive language (netlist), which serves as an important tool in automating the simulation process. The automation developed in generating the computational model and conducting the simulation in the electromagnetic transient program enables a quick verification of the impacts when altering any design parameter of the power transformer. For the purpose of comparing theoretical and practical results, a prototype transformer is utilized, which is equipped with measurement points along the windings to collect the waveform of the transient observed at each of the equipment’s discs. The laboratory results enable analyses of the proposed computational model’s performance and suggest corrections to enhance modeling accuracy. In conducting the laboratory tests, a repetitive impulse generator configured to generate the standard impulse (1,2/50μs) is used. This impulse is then employed to feed the computational model, thereby ensuring consistency in the methodology of comparing the results. The modularity of the prototype transformer allows for verifying the model’s accuracy for different winding constructions to encompass the diversification employed in the field currently. A qualitative analysis is presented for some discs present in the prototype transformer assembled under specific configuration in the laboratory environment.