To address the issue of transformer protection misoperation caused by large excitation inrush currents during no-load closing

this paper first uses mathematical tools to analyze the transient current and magnetic flux changes during transformer no-load closing.A model is built on the simulation platform to analyze the influence of different initial closing phase angles and residual magnetism on the excitation inrush current of three-phase transformers.The characteristics of transformer excitation inrush current are summarized

and the principle of magnetic energy transfer and absorption is proposed accordingly.Based on this principle

an electrical model of an excitation inrush current suppression technique using series current-limiting resistors in the transformer closing circuit is designed

and the electrical principle and software control strategy of this technique are explained.Finally

the simulation tool is used to analyze and verify that the technique of using series current limiting resistors in the transformer closing circuit has a significant suppression effect on inrush currents under different conditions.