基于小波变换的交流采样信号消噪技术

Denoising of AC Sampling Based on Wavelet Transform

针对电力系统交流采样数字信号分析的需要 ,研究了小波变换技术在信号噪声抑制方面的应用。交流信号通常含有噪声 ,一般分为白噪声或有色噪声 ,A/D卡采样也会混入宽频带的噪声 ,即所谓采集噪声 ,利用小波变换的低通特性可以达到较好的消噪效果。通过模拟计算表明 ,经小波消噪后的波形变得光滑 ,信号的信噪比可提高约 5 0dB ,而且波形的过零点和峰值与原始波形基本一致 ,偏离范围在 0 .0 1°之内 。

For dealing with the periodic AC sampling, a new algorithm is presented, with which the noise in digital signal can be eliminated by wavelet transform. Usually, AC signal has white noise or colored noise, and ADC sampling signal is interfused with broad band noise, the sampling noise. The low-pass character of wavelet transform can be used to eliminate these noises. The simulative calculation result indicates that the waveform becomes smoother, the SNR increases about 50 dB, the zero points and peak points are just as the original, with the difference less than 0.01 degree. It simplifies the wave parameter calculation.