電力變壓器直流偏磁問題的研究

1、河 北 工 業(yè) 大 學(xué)畢業(yè)設(shè)計說明書 作 者： 耿錚 學(xué) 號： 110644 學(xué) 院： 電氣工程學(xué)院 系(專業(yè))： 電氣工程及其自動化 題 目： 電力變壓器直流偏磁問題的研究 指導(dǎo)者： 劉宏勛 副教授 評閱者： 李永建 副教授 2015

2、年 6 月 10 日河北工業(yè)大學(xué) 2015 屆本科畢業(yè)設(shè)計說明書II畢 業(yè) 設(shè) 計 （ 論 文 ） 外 文 摘 要Title The Study of Issue about Power Transformer under DC Bias AbstractDC flowing into transformer windings through neutral points is an abnorma

3、l work situation of the transformer. It affects power supply quality and the correct operation of the relaying protection system. Therefore, the study of the study on DC bias of a power transformer is of great importance

4、.Firstly, the present status of research on this issue is generally introduced. And the reason of appearance of DC in the AC grid is elaborated. Next, the mechanism of DC bias in a single phase transformer is analyzed.Se

5、condly, a simulation model of single phase transformer is established utilizing MATLAB/SIMULINK. Under over excitation and DC bias situation, the waveform and harmonics values of exciting current are compared. Meanwhile,

6、 the variation trend of iron core hysteresis curve is obtained. Also, the model of three-phase three-leg transformer and three-phase main transformer are established to compare their ability to bear DC bias.The results o

7、f simulation show that when DC bias in a transformer happens, the iron core of the transformer will be saturated semi-periodically. The peak value and secondary harmonic component in the exciting current will increase si

8、gnificantly. Meanwhile, iron hysteresis curve will move towards right and top; Three-phase three-leg transformer has a better ability to bear DC bias than three-phase main transformer.Keywords：power transformer, DC bias,