With two big waveform characteristics of the transformer excitation inrush current revealed, this paper makes full use of the waveform characteristics,and then proposes a method of distinguishing the transformer excitation inrush current and internal fault current. This method is based on the assumption that the inrush current waveform presents the spire concave arc characteristics and fault current presents the sine waveform characteristics, and in half a cycle samples values can find the extreme value point,frequency, forming the corresponding virtual sine wave. Judging the similarity between the closing current and the tectonic waveform in half-wave cycle can distinguish between the excitation inrush current and fault current. The simulation results show that this method can effectively and quickly remove the internal faults of the transformer, and is not influenced by the aperiodic current components.%在揭示变压器励磁涌流两大波形特征的基础上,充分利用波形特征,提出一种利用波形特征区分变压器励磁涌流和内部故障电流的方法,该方法基于涌流波形呈现出尖顶波的凹弧特征,而故障电流基本保持正弦波形特征,在半波周期内找到采样值的极值点及频率,构造出与之对应的虚拟正弦波形,通过判断合闸电流与构造波形在半波周期内的相似程度来区分励磁涌流和故障电流.仿真结果表明,该方法能够有效、快速切除变压器内部故障,并且不受电流非周期分量的影响.
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