Study On Power Signal Denoising And Weak Signal Detection

Noise is an unavoidable phenomenon in the process of signal detection.Noise will cause the target signal to be submerged in the noise interference,which will distort the signal and reduce the signal-to-noise ratio.Noise will cause adverse effect on signal detection and processing technologies such as signal parameter measurement,feature extraction and disturbance diagnosis.For the power signal,when the signal-to-noise ratio is less than 35 decibels,the signal will be completely annihilated by the noise interference under the background of strong external noise.And the eigenvalues of the signal to be measured will be more difficult to extract.Therefore,in the process of electrical measurement,it is necessary to use appropriate denoising algorithm to suppress the noise interference,so that the noisy signal can be restored to the state of low or no noise to the greatest extent,which aims to increase the signal-to-noise ratio of the output and to achieve the effect of denoising.Otherwise,it is necessary to extract the parameters and eigenvalues of weak signal under strong noise background,which aims to obtain the frequency,amplitude,phase and other information of weak signal.So that the reduction of noise interference and the detection of weak signals are realized.Therefore,this paper focuses on the study of power signal denoising under noise background and weak signal detection under strong noise background.The detail contents are as follows:(1)On the basis of sorting out and comparing the traditional denoising methods of power signal,a new denoising algorithm based on variational mode decomposition is proposed to overcome the shortcomings of the traditional methods.In this way,the potential of variational mode decompositio algorithm in the field of signal denoising is also explored preliminarily.(2)Based on the basic principle of lock-in amplifier and the application of virtual instrument platform software,the design of narrowband low-pass filter for multi-rate digital signal processing is realized,and a multi-rate digital signal processing lock-in amplifier platform based on virtual instrument platform is built to measure the weak sinusoidal signal accurately.(3)Applying the scheme of digital lock-in amplifier based on virtual instrument platform to thje embedded DSP processor,and TMS320F28335 is selected as the core processor.The design scheme of orthogonal vector dual-channel digital lock-in amplifier based on DSP platform is realized,and the feasibility of the design scheme based on DSP platform is verified.