随着蒙东地区±500kV伊穆直流输电工程的投运，直流输电单极-大地回线运行方式引起蒙东地区变压器直流偏磁导致变压器振动、噪声增加，对电网安全运行造成极大威胁。针对这一威胁，研究直流偏磁产生机理和对电网影响，确定蒙东地区直流偏磁分布并研究抑制措施。　　　研究得出，直流偏磁对电网的影响主要体现在变压器上，直流偏磁对变压器的影响主要是铁芯饱和致使漏磁增加，漏磁导致油箱壁和金属结构件发热量增大，引起变压器油箱内过热，严重危害变压器的绝缘，同时，铁芯饱和会使铁芯磁致伸缩加剧，导致变压器的噪音增大、振动加剧。　　　经对直流偏磁产生机理的分析，检测直流偏磁必须采用带电检测变压器中性点直流电流的方法，因为伊穆直流单极-大地回线运行方式是一种特殊运行方式，人工检测难以捕捉时机，为此开发出变压器直流偏磁在线监测系统，实时监测变压器直流电流、振动及噪声，并具备数据管理、分析和报警功能。通过对直流偏磁的监测，发现各变电站受到直流偏磁的影响程度与直流接地极的入地电流、相对位置、地质条件有关，而与运行方式无关。据此总结了蒙东地区直流偏磁电流的分布规律，通过对比数据得出结论——对地表电势高的变电站采取直流抑制措施。　　　进一步深入研究，结合蒙东地区的实际情况，对比现有的四种直流偏磁抑制方法优劣，选取电位补偿法设计直流抑制装置，通过数字仿真验证方案可行，开展抑制装置制作工作，最终实现抑制蒙东地区变压器直流偏磁，确保电网安全稳定运行的目标。

　　　With DC ±500kV Yimu put into operation in eastern Mongolia, Caused by HVDC monopolar-ground loops operation mode of transformer, transformer DC magnetic bias causes vibration, noise increasing, causing great threat to the safe operation of the grid . This article is to address this threat , trying to find out the cause, determine the distribution and detecting correct measure to successfully suppressed. 　　　Research indicates that The influence of DC magnetic bias of the grid is main to the transformer,DC magnetic bias of transformer causes iron-core saturation,Magnetic flux leakage increasing，causing heat increasing of tank wall and metal components to overheat, serious harm to the insulating of transformer and other damage,eg iron - core magnetostrictive exacerbate,vibration and noise increasing.　　　By analyzing the mechanism of DC magnetic bias, The detecting of the DC magnetic bias must by measuring the DC current of the Transformer neutral,becasue Yimu HVDC monopolar-ground loops operation mode is a special mode,so we develop a transformer DC bias line monitoring system, throughing this system ,we can more comprehensive real-time monitoring of DC current, vibration and noise, and can store and manage real-time, analyzing test data, and an alarm. By the monitoring ,We found that the substation DC bias by the degree of influence with the DC grounding pole into the ground current, relative position, geological conditions, and has nothing to do with the operation mode. Which summarizes the eastern Mongolia DC bias current distribution, the proposed high electric potential on the surface substation DC suppression measures taken .　　　In contrast to the four existing DC bias suppression method based on the combination of eastern Mongolia actual production conditions, select the potential compensation method designed DC suppression device. Digital simulation, prototype test run is to describe the results of this work and practical. Finally realized the goal of suppression transformer DC magnetic bias of eastern Mongolia, ensuring the completely stable operation of the grid.