Improved method of hybrid harmonic detection based on fft and dwt
A harmonic detection and harmonic signal technology, applied in the field of signal processing, can solve the problems of inability to distinguish multiple harmonics at high frequencies and low accuracy of low-frequency steady-state signal analysis, and achieve accurate results
Active Publication Date: 2022-03-08
SHANDONG UNIV
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[0004] The present invention aims to solve the technical problem that the accuracy of the low-frequency steady-state signal analysis of the existing harmonic detection method is low, and the high-frequency cannot distinguish multiple harmonics, and provides a method based on FFT and DWT to improve the accuracy of steady-state harmonic detection. Improved Method of Hybrid Harmonic Detection
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[0031] Referring to the accompanying drawings, the present invention will be further described in detail with specific embodiments.
[0032] like figure 1 As shown, the original signal is decomposed into low-frequency steady-state components and high-frequency steady-state components after discrete wavelet transform (DWT). For the low-frequency part reconstructed by discrete wavelet transform, window interpolation FFT processing is performed to obtain each low-frequency steady-state harmonic, which further improves the accuracy of steady-state harmonic detection (window interpolation FFT processing, window function is applied In FFT to suppress spectral leakage, interpolation is used to solve the fence effect problem). Aiming at the high-frequency part reconstructed by discrete wavelet transform, fast Fourier transform is carried out, and the three cases after fast Fourier transform are processed differently. First, let the high-frequency part reconstructed by wavelet transf...
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The invention discloses an improved hybrid harmonic detection method based on FFT and DWT, which solves the technical problems that the accuracy of low-frequency steady-state signal analysis in the existing harmonic detection method is low, and high-frequency cannot distinguish multiple harmonics. Use DWT to decompose the original signal into a high-frequency part and a low-frequency part. After the decomposition is completed, perform window interpolation FFT processing on the reconstructed low-frequency part to improve the spectrum leakage and fence effect problems existing in the original mixed harmonics only using FFT; the reconstructed high-frequency part performs successive judgments on the existence of attenuation signals , if there is no attenuation signal, perform windowed interpolation FFT processing, otherwise, it is necessary to detect the frequency of the attenuated signal, use windowed interpolation FFT to restore all smooth harmonic signals, and subtract them from the reconstructed signal of this layer in turn, and finally get Attenuates the signal. The invention is widely used in the technical field of signal processing.
Description
technical field [0001] The invention relates to the technical field of signal processing, in particular to an improved hybrid harmonic detection method based on FFT and DWT. Background technique [0002] Today's mainstream harmonic detection method is to choose the most widely used harmonic detection method based on FFT and the harmonic detection method based on DWT with good development prospects for research. Analyze its principle from the theory, construct typical harmonic simulation signals, and analyze their respective application scope and limitations in combination with MATLAB. FFT has high detection accuracy for steady-state harmonic signals, but its analysis results do not contain time-domain information, so it is powerless to analyze time-varying harmonic signals; using FFT to sample the power signal for the entire period will inevitably lead to spectrum leakage and the barrier effect; DWT benefits from the idea of multi-resolution analysis and can be used for t...
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IPC IPC(8): G01R23/16
CPCG01R23/16
Inventor 王小利赵晨孙洁王桂硕谭文
Owner SHANDONG UNIV