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Harmonic wave detection method based on Fourier transformation

A technology of Fourier transform and harmonic detection, applied in the field of signal processing, can solve the problem of unsatisfactory real-time performance of the quasi-synchronous sampling method, and achieve the effect of real-time improvement and accurate measurement

Active Publication Date: 2013-01-09
BEIHAI SHENLAN SCI & TECH DEV
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Problems solved by technology

[0014] Aiming at the unsatisfactory real-time performance of the quasi-synchronous sampling method, a solution to improve real-time performance while ensuring high measurement accuracy is proposed

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  • Harmonic wave detection method based on Fourier transformation
  • Harmonic wave detection method based on Fourier transformation
  • Harmonic wave detection method based on Fourier transformation

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Embodiment Construction

[0032] The present invention proposes a new method based on Fourier transform harmonic detection, which will be described in detail below in conjunction with examples, but not as a limitation of the present invention. In this example, the highest harmonic is the 63rd, and the main parameters are selected as follows:

[0033] 1. The sampling frequency is: Fs=50*128*40;

[0034] 2. Power grid fundamental frequency: fluctuates between 47Hz and 53Hz;

[0035] 3. Sampling time of each set of data: 0.044375s;

[0036] 4. Filter index: Wp=60Hz, Ws=135Hz, Rp=0.5db, Rs=50db;

[0037] 5. Filter sampling frequency: 50*128*2Hz;

[0038] 6. FFT operation data length: 2*N=128.

[0039] The processing flow diagram of this example is as follows figure 1 As shown, the signal is sent to DSP for processing after A / D conversion (analog-to-digital conversion), and the fundamental wave period is obtained after filtering, and 128 points are evenly extracted in one signal period, and finally FFT...

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Abstract

The invention discloses a harmonic wave detection method based on Fourier transformation, comprising the following steps: (1) carrying out oversampling and analog-to-digital conversion on a measured signal, and ensuring that data of two signal periods can be sampled from each group of data according to the maximum periodic value estimated by the measured signal; (2) filtering harmonic wave components outside fundamental waves by a digital low pass filter; (3) calculating a fundamental wave period by a periodic method; (4) extracting 2*N numbered data points within one period, wherein, N-1 is the highest harmonic order number; and (5) calculating the parameter of each harmonic wave component by utilizing a synchronous sample FFT. The method of the invention belongs to the signal processingtechnical field, and also can be used for spectrum analysis of other signals. Very high harmonic wave detection accuracy can be obtained by the method; the instantaneity can be doubled compared with three to five signal periods of a quasi-synchronizing method; and the time of two signal periods are only needed, and the fundamental wave frequency also can be accurately measured.

Description

Technical field: [0001] The invention relates to a method for harmonic detection and fundamental frequency measurement in power systems, specifically a method for detecting harmonic parameters based on synchronous sampling FFT (fast Fourier transform), which belongs to the technical field of signal processing and can also be used for other Spectrum analysis of the signal. Background technique: [0002] The main methods of harmonic detection in power system are: harmonic detection based on analog band-pass or band-stop filter, harmonic detection based on instantaneous reactive power, harmonic detection based on Fourier transform, harmonic detection based on neural network, Harmonic detection based on wavelet transform. [0003] Harmonic detection based on analog bandpass or bandstop filters is an early analog harmonic measurement method. The analysis method based on the theory of instantaneous reactive power has great advantages in solving the real-time measurement of the t...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R23/167
Inventor 姚普粮劳永浩韦甘铭龙光成林朝光
Owner BEIHAI SHENLAN SCI & TECH DEV
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