变压器剩磁的制备及对绕组变形测量的影响  

Transformer Remanence Preparation and Influence on Winding Deformation Measurement

作　　者：陈承 罗勇芬[1] 孙玟玟 王国利 王婷婷 程新博 CHEN Cheng;LUO Yongfen;SUN Wenwen;WANG Guoli;WANG Tingting;CHENG Xinbo(School of Electrical Engineering,Xi'an Jiaotong University,Xi'an 710049,China;Electric Power Research Institute,CSG,Guangzhou 510663,China)

机构地区：[1]西安交通大学电气工程学院,陕西西安710049 [2]南方电网科学研究院,广东广州510663

出　　处：《变压器》2024年第9期26-35,共10页Transformer

摘　　要：为了研究变压器剩磁的影响,本文作者了提出了一种剩磁的高效制备方法。对变压器绕组反并联二极管,直流激励该绕组后分闸使励磁电流经二极管续流,基于法拉第电磁感应定律推演的离散公式迭代计算得到退磁轨迹和剩磁值。利用该法对饱和磁感应强度2.05T的铁心获得了精确的1.72T剩磁。进而,试验研究了剩磁对变压器三类绕组变形测量的影响。测量短路阻抗时,剩磁虽影响到励磁支路,然而励磁电流的分流仍很小,因而短路阻抗几乎不受影响。在频率响应分析时(FRA),绕组表现为实心绕组,剩磁通过变化的、依赖于频率的磁导率来影响绕组的频率响应:主要影响在2kHz以下的超低频段并引起响应曲线右移,虽然FRA通常建议避开该频段,但由该频段响应的变化可发现剩磁,并能在变压器合闸运行前给出消磁建议;剩磁对更高频段存在略微影响,不足以干扰对绕组状态的判断。An efficient remanence preparation method is presented in this paper. A transformer winding with an anti-paralleled diode is excited by a DC source to stability, then the source is switched off and the magnetizing current is continuous through the diode.The demagnetization trace and residual magnetic value are obtained by iterative calculation based on the discrete formula deduced from Faraday's law of electromagnetic induction. Using this method, the accurate residual magnetism of 1.72T was obtained from the saturated magnetic induction strength 2.05T of the iron core.Furthermore, the influence of core remanence on the measurement of three types of transformer winding deformation is experimentally studied. When measuring the short-circuit impedance, the residual magnetism affects the magnetizing branch whose current shunt is still very small, so the short-circuit impedance is hardly affected. When Frequency Response Analysis(FRA) is used, the winding is considered as a solid core coil, and due to the variable frequency-dependent permeability, the residual magnetism affects the winding frequency response in such way: the mainly influence is on the ultra-low frequency band below 2kHz and right shifts the response curve. The residual magnetism can be found according to this change, and demagnetization could be suggested before transformer is switched on;the influence of remanence is too small to interfere the judgment of winding status.

关 键 词：剩磁 绕组变形 频率响应分析 

分 类 号：TM401.1[电气工程—电器]