Frequency Adaptive Simulation of Transformer Inrush Current Based on the Augmented Dynamic Phasor Method

The overshoot problem can be avoided by adopting small time step in electromagnetic simulations, and the inrush current of a large capacity transformer usually decays very slowly which will certainly results in low simulation efficiency. In this paper, an augmented dynamic phasor multitimescale electromagnetic transient model was established for large-capacity transformer with nonlinear excitation branch, and a dynamic phasor flux prediction method was utilized. The current can be accurately predicted and simulated, which solves the overshoot problem of piecewise linearization under large time steps, and large time steps can be adopted without sacrificing more current harmonic components. When the inrush current occurred, a small-time step was adopted to predict the flux linkage, then magnetizing inrush current was obtained by current-flux curve fitting function. When the flux linkage spectrum was detected concentrated near the fundamental frequency, the flux linkage waveform will maintain its sinusoidal characteristics then a large time step can be adopted without sacrifice of simulation accuracy. In this way, the accurate inrush current was simulated utilizing current-flux curve fitting function, and the overshoot problem was solved using large step size to accelerate the simulation speed. Finally, the simulation results verified the correctness of the proposed transformer model and dynamic phasor prediction method. © 2022 Chinese Machine Press. All rights reserved.