基于矩阵束的换流变压器对称性励磁涌流识别方法

A Method for Identifying Symmetrical Magnetizing InrushCurrent of Converter Transformer Based on Matrix Pencil

在特高压直流输电中,换流变压器具有大差保护和小差保护。特高压直流输电的换流站通常为两个换流变压器并联,当其中一个换流变压器空载合闸时,在与其并联的换流变压器上可能出现和应涌流,由于大差保护为两个换流变压器的小差保护差流之和,因此大差保护的差流为励磁涌流与和应涌流的和,为对称性励磁涌流。由于对称性励磁涌流二次谐波含量低,因此不易从波形上识别,但矩阵束可以识别信号各谐波分量的幅值和衰减时间常数,因此矩阵束的这一特性可以区分故障电流、励磁涌流和对称性励磁涌流。分析对称性励磁涌流的形成机理,建立特高压换流站模型。仿真测试结果验证了矩阵束方法的有效性。

In UHV DC transmission,the converter transformer is equipped with large differential protection and small differential protection.The converter station of UHV DC transmission usually has two converter transformers in parallel.When one of the converter transformers is switched on at no load,there may be sympathetic inrush on the converter transformer in parallel.Since the large differential protection is the sum of the differential current of small differential protection of two converter transformers,the differential current of the large differential protection is the sum of magnetizing inrush current and sympathetic inrush,which is the symmetrical magnetizing inrush current.Due to the low second harmonic content,it is not easy to identify symmetrical magnetizing inrush current from the waveform.The matrix pencil can identify the amplitude and decay time constant of each harmonic component of the signal,so it can distinguish fault current,magnetizing inrush current and symmetrical magnetizing inrush current.The formation mechanism of symmetrical magnetizing inrush current is analyzed,and a UHV converter station model is established.The simulation test results verify the effectiveness of the matrix pencil method.