典型高阻抗变压器励磁涌流条件下电磁及机械特性研究

Research on Electromagnetic and Mechanical Characteristics of Typical High Impedance Transformers under Excitation Inrush Current Conditions

随着电网发展系统容量增大,具有成本低、额外占地面积小、限制系统短路电流能力强等特点的高阻抗变压器应用率不断提高。但是,高阻抗变压器因其空载合闸励磁涌流过大,导致零序涌流增大,从而增加了变压器所连母线上零序过流保护的误动风险,同时,国内外又缺少对高阻抗变压器系统性的研究。首先通过Maxwell有限元软件建立4种高阻抗变压器及同电压等级的普通变压器的二维仿真模型,研究变压器绕组及铁心之间的差异;然后开展了变压器励磁涌流特性的研究,明确了5种变压器之间的特性差异;最后,分析了变压器的磁密及电磁力之间的差异。从多方面入手,对高阻抗变压器进行了较为详细地、综合地研究,包括了当前所有的高阻抗变压器结构,为后续针对高阻抗变压器的研究提供了参考。

With the development of the power grid and the increase in system capacity,the application rate of high impedance transformers with characteristics such as low cost,small additional footprint,and strong ability to limit system short-circuit current is constantly increasing.However,high impedance transformers have a high surge current due to their no-load closing excitation,resulting in an increase in zero sequence surge current,thereby increasing the risk of misoperation of zero sequence overcurrent protection on the busbar connected to the transformer.At the same time,there is a lack of systematic research on high impedance transformers both domestically and internationally.First,two-dimensional simulation models of four types of high impedance transformers and ordinary transformers of the same voltage level are established using Maxwell finite element software,and the differences between transformer windings and iron cores are studied.Then,research is conducted on the excitation inrush current characteristics of transformers,clarifying the characteristic differences between the five types of transformers.Finally,the differences between the magnetic density and electromagnetic force of the transformer are analyzed.Started from multiple aspects,a detailed and comprehensive study is conducted on high impedance transformers,including all current high impedance transformer structures,providing certain reference value for subsequent research on high impedance transformers.