电能质量约束下变压器承受直流偏磁能力的分析  

Analysis on the Withstanding Ability of Power Transformers to DC Bias Under Power Quality Constraints

作　　者：李长云[1] 李庆民[1] 李贞[1] 姚金霞[2] 刘民[2] 

机构地区：[1]山东大学电气工程学院,济南250061 [2]山东电力研究院,济南250002

出　　处：《高电压技术》2010年第12期3112-3118,共7页High Voltage Engineering

基　　金：教育部新世纪优秀人才支持计划(NCET-08-0335);国家电网公司科技基金(5250909)~~

摘　　要：直流偏磁现象将影响变压器的正常运行,变压器承受直流偏磁的能力是电力系统稳定运行的前提。为此,基于铁芯的折线式等效模型,利用电磁关系方程导出了变压器输出电压与偏磁电流间的数值关系。进而根据系统的电能质量约束条件,基于电压调整率和电压总谐波畸变率,建立了确定变压器所能承受的最大偏磁电流的有效判据,并给出了仿真验证。仿真结果表明,变压器铁芯的饱和系数以及负荷的功率因数大小,都将影响变压器承受直流偏磁的能力,评估时需综合考虑。该研究为电力变压器的设计、运行以及发展直流偏磁的抑制方法提供了参考依据。The DC bias phenomenon will cause impacts on normal operation of power transformers,and the withstanding ability of power transformer to DC bias is the prerequisite to the stability of power system.Based on a piecewise linear model of the iron core,the mathematical expressions between the transformer output voltage and the DC bias were deduced by virtue of the fundamental electromagnetic equations.Further,by incorporating the power quality constraints of power systems,effective criterions were established based on both the voltage regulation rate and the total harmonic distortion rate to determine the maximum possible DC bias current that the transformers could withstand,and simulations were also given to verify the analyzed results.Analysis also indicates that,both the saturation factor and the load power factor may execute sensible effects on transformers＇capability to withstand DC bias,which should be considered comprehensively for assessment.The research presents useful reference for the design and operation of power transformers,as well as for further developing methodology to suppress DC bias.

关 键 词：电力变压器 直流偏磁 直流偏磁电流 电压调整率 谐波畸变率 饱和系数 

分 类 号：TM401[电气工程—电器]