变压器励磁涌流引起线路差动保护误动分析

探讨变压器空投过程中,为其供电的110k V线路差动保护动作跳闸原因。通过对变压器涌流波形、110k V线路两侧电流波形,以及线路保护的稳态量差动、零序差动、变化量差动分别加以分析,得出结论:线路两侧光纤电流差动保护用TA暂态特性差异较大,在空投变压器产生的励磁涌流作用下出现暂态饱和,导致线路变化量差动保护误动跳闸。为避免发生此类情况,同一线路两侧应尽可能选用饱和特性一致且变比相近的TA。

Analysis of Line Differential Protection Maloperation Caused by Transformer Inrush Current

The reason of differential protection action and trip out of an 110 kV transmission line during the no-load start process of a transformer whose power is supplied by the 110 kV transmission line is discussed. Based on the analysis of inrush current waveform of the transformer, current waveforms on both side of the line, steady-state component differential, zero sequence differential and variation component differential of line protection, it is concluded that TAs used by optical current differential protections on both side of the line have too much transient characteristic differences which reached transient saturation under the action of the inrush current generated by the no-load start process of the transformer and caused the maloperation of variation component differential protection and the trip out of the line. In order to avoid similar situation, TAs which have same saturation characteristics and similar ratio should be chose on both sides of the line