An improved transformer model considering of the losses and hysteresis of the core

In order to analyze the power system transient process or ferromagnetic resonance problems, a precise equivalent nonlinear model of a transformer is important. Based on no-load transformer test, an equivalent circuit model of the transformer and a calculation method of magnetizing branch parameter are proposed, which uses nonlinear resistors and parallel connection between inductance considering nonlinear and hysteresis. The equivalent circuit of a model transformer magnetizing branch circuit model is implemented through no-load test measurement in the paper. The calculated results are found to be in good agreement with the measured data. Simultaneously, this method is also used to establish a circuit model of an origin single-phase three-limb transformer, JMB500. Again, and the computed results agree well with the measured data. Finally, the equivalent circuits of transformer model are obtained at different frequencies and the comparison between the computed data and the measured data also shows good agreement, which proves the validity and accuracy of the modeling method proposed in this paper. © 2016, The editorial office of Transaction of China Electrotechnical Society. All right reserved.