基于波形上下对称系数识别励磁涌流的新原理

提出一种新的识别变压器励磁涌流和故障电流的新原理。该原理首先计算一周波差流波形的上下对称系数，然后根据上下对称系数鉴别涌流和故障。故障电流波形具有上下对称的特征．上下对称系数近乎零值．即便含有较大衰减直流分量的情况下其值也不超过0．10；而单向涌流波形上下不对称．上下对称系数较大，一般大于0．15，在某些特定合闸角及剩磁的条件下其值较小．但仍大于0．10。本方法原理清晰，计算简单，且算法本身可以有效地抑制高次谐波，并具有抗CT饱和的能力。

Novel Theory of Identifying Inrush Current Based on Waveform Longitudinal Symmetry

A novel theory based on wave form longitudinal symmetry is proposed to identify inrush current and fault current.Fault current waveform has character of symmetry so its longitudinal symmetry value is nearly zero and not more than 0.10,but inrush current waveform is longitudinal asymmetrical so its longitudinal symmetry value is large and more than 0.15 in most conditions.The results of simulation demonstrated this theory is valid and can resist CT saturation and high harmonics.