基于外部直流激励的电力变压器剩磁评估与试验验证  

Residual Flux Evaluation and Experimental Validation of Power Transformer Based on External DC Excitation

作　　者：李鹏 董明鑫 李刚 汪可 张书琦 李金忠 LI Peng;DONG Mingxin;LI Gang;WANG Ke;ZHANG Shuqi;LI Jinzhong(China Electric Power Research Institute,Haidian District,Beijing 100192,China;State Grid Corporation of China,Xicheng District,Beijing 100031,China)

机构地区：[1]中国电力科学研究院有限公司,北京市海淀区100192 [2]国家电网有限公司,北京市西城区100031

出　　处：《电网技术》2022年第10期4122-4130,共9页Power System Technology

基　　金：国家电网公司科技项目(GY71-17-050)。

摘　　要：变压器铁心在进行直阻测量、变比测量、检修试验后不可避免地会产生剩磁,剩磁使得铁心饱和,引起励磁涌流、差动保护误动,严重影响变压器的可靠运行。该文从剩磁产生的机理出发,研究提出了用于变压器剩磁评估的外部直流激励法,首先在实验室搭建了3kV单相四柱变压器模型的剩磁试验平台,开展了等幅值与不等幅值电流下的剩磁模拟和评估试验,结果表明等幅值电流法精度更高,等幅值电流法最大相对误差小于4.5%,饱和段平均相对误差为4.13%,线性段、膝点段误差相近,平均相对误差小于1.5%;不等幅值电流法线性段、膝点段、饱和段平均相对误差为5.27%。然后,在大容量实验室开展了500k V单相变压器的剩磁模拟、评估以及空载合闸试验验证,随机合闸时励磁涌流为达1276A,基于剩磁评估值的选相合闸策略,励磁涌流峰值与额定电流之比均小于2%,验证了方法的有效性。该文研究结果为变压器现场剩磁评估和合闸励磁涌流抑制提供有益参考。Remanence,which is inevitably generated in the transformer core after a DC resistance measurement,a transformation ratio measurement,or a maintenance test,makes the core saturated,causing the excitation inrush current and the mis-operation of the differential protection,which seriously affects the reliable operation of the transformer.Based on the mechanism of remanence generation,this paper proposes an external DC excitation method for the transformer remanence assessment.Firstly,a 3kV single-phase four-column transformer model remanence test platform was built in the laboratory.The remanence simulation and evaluation tests under the constant and unequal amplitude currents were carried out.The results show that in the equal-amplitute current method there is a higher accuracy,the maximum relative error of which is less than 4.5%.The average relative error of the saturation section is 4.13%,and those of the linear section and the knee section have similar values of less than 1.5%.While in the unequal amplitude current method,the average relative error of the linear segment,the knee segment and the saturation segment is 5.27%.Then,the remanence simulation,evaluation and no-load closing test verification on the 500kV single-phase transformer were carried out in a larger-capacity laboratory.The magnetizing inrush current reached 1276A during a random closing.By using the phase-selective closing strategy based on the residual magnetization evaluation value,the ratio of the peak value of the magnetizing inrush current to the rated current is reduced to less than 2%,which verifies the effectiveness of the method.The research results in this paper provide a useful reference for the on-site remanence assessment of the transformers and the suppression of inrush current during closing.

关 键 词：剩磁评估 电压积分法 外部直流激励法 空载合闸 励磁涌流 

分 类 号：TM721[电气工程—电力系统及自动化]