智能电网数字锁相技术和小波变换的微弱信号测量研究

The study about weak signal detection based on digital lock-in technique and wavelet transform

针对目前数字锁相算法对低信噪比微弱信号提取质量不高、计算时间长的弊端,提出用小波变换滤波器代替传统数字锁相系统的输出滤波器,并对小波变换滤波器分解级数、阈值选取策略和小波基选择做了讨论,以脉冲信号为例进行了参数选择。通过模拟仿真对比分析了小波滤波数字锁相系统和巴特沃斯滤波器数字锁相系统的性能,结果表明在各种信噪比下前者的性能均优于后者。

In this study,an improved digital lock-in technique with a wavelet filter is developed instead of traditional output filter in digital lock-in technique to solve the problem that the quality of extracted by traditional digital lock-in system is not so well and the calculate time is long.Oreover,the wavelet De-composition Parameters Selection include the Decomposition Level Selection,The Threshold Strategy Selection and the Wavelet Basis Selection is discussed.Based on pulse signal the wavelet De-composition Parameters is selected.Through the simulation,comparing the performance of digital lock-in technique with a wavelet filter and with Butterworth filter.The conclusions suggest that digital lock-in technique with a wavelet filter is better than with traditional filter.