【作者】 朱芸；

【导师】 乐秀璠；

【作者基本信息】 河海大学 ， 电力系统及其自动化， 2004， 硕士

【摘要】 我国经济近些年来发展迅速，对电力的需求日益增长，电力系统规模不断扩大，大容量变压器在电力系统中的作用日显突出，对其继电保护提出了新的要求。差动保护一直作为电力变压器的主保护，但由于励磁涌流仍然是导致变压器差动保护误动作的主要原因，因此正确鉴别励磁涌流和内部故障电流是保证变压器差动保护可靠运行的关键之所在。 变压器励磁涌流具有明显的奇异性，小波变换具有多尺度分析和良好时频域局部化特性，适合提取信号边缘和峰值突变的特征，能够很好的检测信号奇异性。本文选择适合电力系统信号分析的B样条函数作为母小波，对励磁涌流和内部故障电流进行小波分析，并设计微机型变压器保护基本配置，在以往间断角原理鉴别励磁涌流的基础上，突破传统精确测量励磁涌流间断角的方法，直接对信号小波变换后的波形进行分析，建立一个新的鉴别励磁涌流判据，该判据对硬件要求不高，可以在现有一般硬件平台上实现；并编写以B样条函数为母小波的小波变换判据算法程序。 本文提出的新判据以及相应算法程序在现有的动模实验数据上经过测试，证明该判据可以正确的鉴别出励磁涌流和内部故障电流，在TA发生饱和、间断角出现缺失情况下，不需添加以往恢复间断角的模块，同样可以正确鉴别出励磁涌流和内部故障电流，具有一定的实用价值。更多还原

【Abstract】 With the development of economy in our country recently, there has been more and more requirement of power. The size of power system is enlarged continually, so the function of large transformer in power system is more important, and there is some new requirement for the transformer protection. Differential protection is the master protection for the important power system elements all through, but magnetizing inrush current is still the primary reason that causes transformer protection miss-operating, so distinguishing between magnetizing inrush current and inner fault current correctly is the key that ensuretransformer differential protection operating credibility.Magnetizing inrush current has obvious singularity, and wavelet transform hasmulti-scale and good time-frequency local characteristic, that it is particularly well adapted to extract the characteristic of signal’s edge and peak value, and can check up the singularity well. This thesis chooses B spline wavelet that adapts to the analysis of power system signal, and uses the wavelet transformer to analyze the magnetizing inrush current and inner fault current. A transformer microcomputer protection was designed in this thesis, and in the base of intermission angle principle, a new criterion was established, which pierces through the traditional method with accurate measurement of intermission angle, but analyses the wave by wavelet transform. This criterion is lower in hardware, so it will be realized in the existing hardware. This thesis edited wavelet transform program with B spline wavelet.After the new criterion and its arithmetic program in this thesis have been tested with now experimental data, it has been proved that this criterion can distinguish between magnetizing inrush current and inner fault current. When intermission angle may be vanishing in TA saturation, the new criterion can also distinguish correctly without module that makes the vanishing intermission angle. In conclusion, this criterion has applied value.更多还原