傅氏算法在数字保护中的应用新解与讨论

讨论了傅氏算法在数字保护中应用的几个问题，提出一种新的傅氏算法的理解途径，即旋转相量法。分析出余弦信号可由2个共轭旋转相量来合成，对比复数傅立叶级数在各频率点的复系数，得出幅频特性上负频率点复系数的物理含义．即正频率和负频率点处的复系数可分别等效为逆时针和顺时针匀速旋转的2个共轭相量在零初始时刻的值。此概念有利于正确使用傅氏算法，亦可推广到其他算法应用中。

The New Idea and Discussion of Fourier Algorithm Application in Digital Protection

Several theoretical discussions are presented in this paper. Through the vector analysis of cosine signal,the result is reached that cosine signal could be synthesized by two conjugation spin vector. The physical means of the negative frequency is proved through comparing the complex coefficient of each frequency in Fourier series between the spin forms of any periodical signal. The positive and negative frequencies on frequency property are correspondent with counter-clockwise and clockwise spin vector,which are two conjugates. Finally,the conclusion is applied on digital protection in expression of fault signal,and is further applied on the calculation of sequence component.