基于差动电流正弦曲线拟合波形的变压器保护原理

以变压器的磁化特性曲线为基础,对比分析了变压器差流为涌流和非涌流时的波形特点,进而提出了一种基于差动电流正弦曲线拟合波形的变压器保护原理。为了更能体现励磁涌流的特征和减少拟合波形幅值的计算误差,建议取拟合角度为差动电流峰值时的角度最为合理。给出了拟合波形幅值的计算方法,并讨论了减小计算误差的方法。大量数字仿真结果表明,所提出的原理可以快速、有效地区分励磁涌流和内部故障电流。

Transformer Protection Scheme Based on the Sine Curve Fitting of Differential Current

Based on the characteristics of the transformer magnetizing curve, this paper analyzes the difference between the magnetizing inrush current curve and other currents, and proposes a scheme of transformer protection. In order to distinguish the magnetizing inrush current and reduce fitting error, the angle with the maximal differential current is selected as fitting angle. This paper discusses how to calculate the amplitude of the fitting curve and to obtain the accurate value. The simulation results of the transformer indicate that the protection scheme can distinguish the magnetizing inrush current from the internal fault current rapidly.