微机电力变压器差动保护的研究

根据电力变压器继电保护的要求，设计出微机电力变压器差动保护系统，分析了微机电力变压器差动保护硬件系统的设计原理，给出了该系统的硬件框图．详细地讨论了信号分析工具：傅里叶变换和小渡变换的特点以及它们的使用范围；指出了傅里叶变换在微机电力变压器差动保护中存在的不足．算法采用小波变换，分析了几种小波母函数．针对当前微机电力变压器差动保护存在励磁涌流与内部故障鉴别理论不完善，采用了基于小波变换的判据。提高了微机电力变压器差动保护系统的可靠性和快速性．

Study on differential protection for power transformer based on computer

Aim at the demands of the relay protection for power transformer, this paper designs the system of differential protection for power transformer based on computer, analyzes the principle of hardware design, and presents the block chart . This paper discusses on the characteristic Fourier transform and wavelet transform, gives out the applied range, and points out the shortages of differential protection for power transformer based on computer using Fourier transform. It adopts wavelet transform to analyze the fault signal and some mother function of wavelet. Because theory of distinguishing magnetizing inrush current from internal fault current is not perfect, this paper uses the algorithm based on wavelet transform, so it is high reliable and fast for differential protection for power transformer based on computer.