华电技术 ›› 2019, Vol. 41 ›› Issue (5): 22-27.

• 研究与开发 • 上一篇    下一篇

变压器过励磁五次谐波特征及机制的研究

  

  1. 南京国电南自电网自动化有限公司,南京〓211153
  • 出版日期:2019-05-25 发布日期:2019-06-04

Research on characteristics and mechanism of transformer fifth harmonic under overexcitation condition

  1. Nanjing SAC Power Grid Automation Company Limited, Nanjing 211153, China
  • Online:2019-05-25 Published:2019-06-04

摘要:

现代大型变压器正常运行时磁感应强度取值较大,在短时过电压(过励磁)时,变压器励磁电流将激增,很容易造成差动保护误动,在过电压倍数不大的情况下很有必要利用励磁电流的谐波含量对差动保护进行闭锁。利用两条不同斜率的折线对变压器磁化特性曲线进行拟合,在此基础上推导了励磁电流五次谐波与变压器过电压值的关系表达式,并在电磁暂态仿真软件PSCAD/EMTDC中搭建变压器过励磁模型,对比了理论推导与仿真波形,验证了理论公式的正确性,并对过电压条件下变压器保护五次谐波闭锁定值进行了探讨。

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Abstract:

The magnetic density of modern high-capacity transformers is large while running. In the case of shortterm overvoltage (overexcitation), the transformer excitation current will surge, which can easily cause the maloperation of differential protection. It is necessary to use the harmonic content of the excitation current to lock the differential protection when the multiple of overvoltage is small. The relationship between the excitation current fifth harmonic and the voltage of the transformer is deduced based on fitting 2 lines of transformer magnetic characteristic with 2 different slopes. Transformer overexcitation model is built by the simulation software PSCAD/EMTDC. The theoretical derivation and simulated waveform are compared, which verifies the correctness of the theoretical formula. It discusses the fifth harmonics locking values for transformer protection under overvoltage conditions.

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