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Research on Saturation Characteristics and Modeling Method for Transformer Based on J-A Model

In recent years, with the rapid development of high voltage direct current transmission (HVDC) in China, the saturation problem of transformers has gradually become a hot spot. To study the internal characteristics of the transformer when saturated. Firstly, the magnetization branch of transformer is established based on the Jiles-Atherton(J-A) model. Then a three-phase transformer model considering saturation is established in MATLAB, and the model is used to analyze the harmonic changes of excitation current and the winding current under different load conditions by injecting DC into the neutral point. The result shows that the core is half-cycle saturated after the injection of DC, the current distort ion of the primary winding is mainly related to the excitation current, which is manifested by even harmonics that increase rapidly and the phase core with more direct current intrusion is more saturated.