CAJ | 학술논문

小波阈值降噪是近年来水电机组状态监测信号去噪常用的算法，经典的阈值函数为硬、软阈值两种函数。在硬阈值方法中，处理过的小波系数在阈值处是间断的，得到的估计信号在重构时易产生局部附加振荡；而经软阈值函数降噪的信号虽然整体连续性好，但与原始信号之间总是存在着恒定的偏差，影响重构精度。因此在软、硬阈值函数基础上提出了一种改进阈值函数的小波降噪算法，通过M atlab仿真和实际采集数据的实验结果表明：该方法克服了传统软、硬阈值函数算法的缺点，不仅连续性好，而且提高了信噪比。通过对比降噪后对振动信号特征能量的保留程度，说明改进阈值函数较传统经典去噪方法更为优越，是一种有效的降噪方法。
소파역치강조시근년래수전궤조상태감측신호거조상용적산법，경전적역치함수위경、연역치량충함수。재경역치방법중，처리과적소파계수재역치처시간단적，득도적고계신호재중구시역산생국부부가진탕；이경연역치함수강조적신호수연정체련속성호，단여원시신호지간총시존재착항정적편차，영향중구정도。인차재연、경역치함수기출상제출료일충개진역치함수적소파강조산법，통과M atlab방진화실제채집수거적실험결과표명：해방법극복료전통연、경역치함수산법적결점，불부련속성호，이차제고료신조비。통과대비강조후대진동신호특정능량적보류정도，설명개진역치함수교전통경전거조방법경위우월，시일충유효적강조방법。
Threshold denoising based on wavelet is a commonly used algorithm in the denoising of hydropower unit status monitoring signal in recent years .The classic threshold functions can be divided into hard threshold function and soft threshold function .The wavelet coefficients processed by the hard threshold function are discontinues at the threshold value ,which are prone to cause addi‐tional partial oscillation on the reconstructed signal .The signal denoised by soft threshold function has a better overall continuity , but there is always a constant deviation between the reconstructed signal and the original one ,which is prone to affect the reconstruc‐tion accuracy .Based on this situation ,a wavelet denoising algorithm with an improved threshold function is put forward .The Mat‐lab simulation with the actual collected data indicate that the new method overcomes the drawbacks of classic ones ,not only does it have a good continuity ,but also raises the Signal to Noise Ratio (SNR) .By comparing the preservation degree of characteristic ener‐gy of vibration signals after denoising ,the improved threshold function is superior to the traditional de―noising methods .In summa‐ry ,it is an effective denoising method .