小波变换数字算法及其在高压输电线保护中的应用

Digital Algorithm of Wavelet Transform and Its Application on Protection for Extra High Voltage Transmission Lines

从电力系统继电保护应用的角度 ,结合香农采样定理 ,深入探讨了连续信号和离散信号的小波变换的关系 ,给出了离散信号的积分小波变换和离散小波变换的数字计算方法 .从理论上研究了信号小波变换的误差与尺度函数和小波函数的关系 .结果表明 :小波变换的误差来源一是信号在尺度空间的投影与抽样空间的投影转换 ,二是小波以及尺度函数的选择 .小波的时频定位特性越好 ,即时间频率窗的面积越小 ,计算误差越小 .阐述了小波分析在电力系统高压输电线路的行波保护以及单端暂态量保护中的应用 .

The digital algorithms of integral and discrete wavelet transform are presented for purpose of electric power system protection, based on the analysis of wavelet transform for sampled digital signals under the Shannon sampling theorem. The relationships between the error of wavelet transform and the characteristics of wavelet and scaling function are additionally studied and the results show that the error of wavelet transform calculation mainly depends on calculation of the projection of signal in scaling space and on the selection of wavelet.The better time frequency character of wavelet selected, the more precise in wavelet transform. The introduction of the wavelet application on traveling wave protection and transient based non unit protection for extra high voltage (EHV) transmission lines is also presented in detail.