一种基于数学形态学提取电流波形特征的变压器保护新原理

基于数学形态学方法提取电流波形的局部特征，提出了一种判别变压器励磁涌流和故障电流的新原理。文中利用自定义的峰谷检测器提取出电流波形的峰谷点，在此基础上求取峰谷点之间的形态梯度，进而将其3等分并计算各段形态梯度波形下的面积，根据3段面积的大小规律能够定性地识别出励磁涌流和故障电流。新原理计算量小，易于工程实现。经HYBRISIM的仿真验证，新原理能够有效地区分励磁涌流和故障电流，受CT饱和影响小，在性能上优于二次谐波制动判据和波形比较判据。

A NEW ALGORITHM BASED ON THE MATHEMATICAL MORPHOLOGY FOR POWER TRANSFORMER PROTECTION

A new algorithm of distinguishing the inrush and fault current of power transformer based on the character of current waveform extracted by mathematical morphology is put forward in this paper. The defmition of morphological detector is proposed, which is used to locate the peak and the bottom of current waveform, and then the morphological gradient between them is calculated. By dividing the morphological gradient into three parts with the same size, the area of each part is calculated and the qualitative discrimination based on the relative size of each area can be made. The proposed algorithm needs a few calculations and can be realized easily. Simulation results of HYBRISIM(Hybrid Simulator) show that this algorithm is able to distinguish the inrush and fault current and immune to CT's saturation. Compacted with the second harmonic restraint principle and the waveform comparison principle, the proposed algorithm has better performance.