Abstract：The affluence of DC bias on the transformer magnetizing current was analyzed using the PSCAD electromagnetic transient simulation software on the basis of analyzing the principle of transformer DC bias. The transformer neutral point current, bus harmonic, the transformer vibration and noise were all measured in both cases of monopole and bipolar DC transmission. After a comprehensive analysis of the simulation and measurement, a conclusion was drawn. When the transformer neutral point current is more than 5% of the rated current in the transformer high-voltage side, serious distortion of the excitation current will be caused. The influence of DC bias is most serious on the transformer low-voltage side, because significant displacement had appeared. The displacement of the high-voltage side and low-voltage side changed little, but the speed and acceleration had increased 8-9 times, therefore, the transformer suffered a great impact. Finally, the method of series connecting capacitor with the transformer neutral point to limit the DC bias was proposed.
[1] 李慧奇,崔翔,候永亮,李琳,卢铁兵.直流偏磁下变压器励磁电流的实验研究及计算[J].华北电力大学学报, 2007, 34(4): 1-6. [2] 李晓萍,文习山,陈慈萱.单相变压器直流偏磁励磁电流仿真分析[J].高电压技术, 2005, 31(9): 8-10. [3] 蒋跃强,李红雷,周行星,黄华。变压器直流偏磁的振动特性研究[J].华东电力, 2009, 37(1): 132-135. [4] 谢志平,姜益民,魏本刚.大型电力变压器直流偏磁试验研究[J].变压器, 2011, 48(11): 23-26. [5] 蒯狄正,刘成民,万达.直流偏磁对变压器影响的研究[J].江苏电机工程, 2004, 23(3): 1-5. [6] 蒋伟,吴广宁,刘愈倬.变压器直流偏磁抑制措施的研究进展[J].四川电力技术, 2011, 34(3): 9-13. [7] TAKASU N, OSHI T, MIYAWAKI F, et al. An experimental analysis of DC excitation of transformers by geomagnetically induced currents [J]. IEEE Transactions on Power Delivery, 1994, 9(2): 1173- 1182. [8] PICHER P, BOLDUC L, DUTIL A, et al. Study of the acceptable DC current limit in core-form power transformers[J]. IEEE Transactions on Power Delivery, 1997, 12(1): 257-265.
2013, Vol. 14 
