Modeling of Three-limb Core-type Power Transformer No-load Closing Excitation Inrush Current

摘要

In this paper, the principle of excitation inrush current is explained with the help of transformer magnetization curve and formula. A statistical simulation model of three-phase no-load transformer closing is built in the ATP-EMTP simulation software. The effects of the magnetic and circuit breaker pre-breakdown characteristics on the inrush current were analyzed by statistical simulation. This study proposes an analytical-numeric method in the time range to accurately determine the inrush current of the three-phase three-link transformer, taking into account the nonlinear behavior of the iron nucleus. The proposed method is aimed at obtaining equations for the start current, as well as the flow of the magnetic core by applying an iterative approach based on simulation.