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Harmonic detection method and detection system based on frequency shift ensemble empirical mode decomposition

A technology of harmonic detection and acquisition module, applied in the direction of spectrum analysis/Fourier analysis, etc., can solve the problem that the high harmonics cannot be completely separated due to the frequency, so as to overcome the fluctuation of the power grid, expand the scope of application, and enhance the applicability Effect

Active Publication Date: 2017-01-11
HEBEI UNIV OF TECH
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  • Application Information

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Problems solved by technology

This method can overcome the problem of intermittent signal interference in the harmonic detection environment, and at the same time improve the scope of application; it effectively solves the problem that high-order harmonics cannot be completely separated due to similar frequencies, and can accurately express the various aspects of the signal on the time-frequency plane. class information

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  • Harmonic detection method and detection system based on frequency shift ensemble empirical mode decomposition
  • Harmonic detection method and detection system based on frequency shift ensemble empirical mode decomposition
  • Harmonic detection method and detection system based on frequency shift ensemble empirical mode decomposition

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Embodiment 1

[0062] use figure 1 In the system, the signal source sends a voltage signal with an amplitude of 1V, a frequency of 50Hz fundamental wave and an amplitude of 0.5V, and a frequency of 150Hz as a superimposed voltage signal as a test signal, which is connected to the host data acquisition module 12 and the slave Data acquisition module 21. Since the signal source sends out a fixed frequency signal, there is no fluctuation effect, so the master and slave in the harmonic detection system are based on the power frequency of 50Hz.

[0063] The specific steps of the harmonic detection method based on frequency shift set empirical mode decomposition are (see Image 6 ):

[0064] Step 1): Collect data for 5 cycles, and perform EEMD decomposition on the data: In the harmonic detection system, both the host and the slave set the sampling frequency to 12800 Hz, and the number of sampling points for 5 cycles based on the power frequency of 50 Hz is 1280 points. The host computer collect...

Embodiment 2

[0067] use figure 1 In the system, the signal source sends a current signal with an amplitude of 1V, a frequency of 250Hz fundamental wave and an amplitude of 0.5V, and a frequency of 350Hz as a superimposed current signal as a test signal, which is connected to the host data acquisition module 12 and the slave Data acquisition module 21. Since the signal source sends out a fixed-frequency signal, there is no fluctuation effect, so the measured power frequency of the phase-locked loop circuit of the slave in the harmonic detection system is not used. Both the master and the slave are based on the power frequency of 50Hz. According to the decomposition condition of EEMD, two signals x 1 and x 2 The frequency ratio between is at least twice the relationship that f 1 ≥2f 2 , while satisfying the signal x 1 frequency f 1 with amplitude a 1 The product of needs to be greater than the signal x 2 frequency f 2 with amplitude a 2 the product of a 1 f 1 ≥a 2 f 2 . Accor...

Embodiment 3

[0079] use figure 1 In the system described above, the three-phase power is fed into the voltage regulator to output a voltage of 60V, and then the three-phase power passes through the three-phase rectifier bridge, and the load end of the rectifier bridge is connected to a resistor box with a resistance value of 20Ω, so that a 3A rectification signal will be generated. In the embodiment, the harmonic decomposition of the A-phase rectified signal is used as the test signal, which is connected to the master data acquisition module 12 and the slave data acquisition module 21 . The host sampling frequency is configured with a data acquisition card, the sampling frequency is 12800Hz, and 1280 points are collected; since this is directly connected to the power signal, the slave machine connects the A-phase voltage of the three-phase electric power signal to the slave machine in order to achieve a more accurate purpose. The phase-locked loop circuit, the output signal of the phase-lo...

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Abstract

The invention discloses a harmonic detection method and detection system based on frequency shift ensemble empirical mode decomposition. According to the method, signals are converted by employing Hilbert transform, conditions of ensemble empirical mode decomposition are satisfied through frequency shift, and the problem of higher harmonic separation is solved. According to the method, the problem of intermittent signal interference in a harmonic detection environment can be overcome, and the application range can be extended; the problem that higher harmonics cannot be completely separated due to similar frequencies is effectively solved, and various kinds of information of the signals on a time frequency plane can be accurately expressed; the system employs an industrial personal computer and a DSP as core devices; the industrial personal computer is regarded as a host, detection of a complex algorithm is realized, the effect thereof is verified, and acquisition of harmonic signals is realized by employing a data acquisition card; and the DSP is regarded as a slave and used for verifying the practicality of the complex algorithm, a phase-locked loop circuit is employed, the power grid frequency fluctuation influence is overcome, the voltage frequency of the power grid can be accurately detected, and the precision of harmonic detection is improved.

Description

technical field [0001] The invention relates to digital signal processing technology, in particular to a harmonic detection method and a harmonic detection system based on frequency shift set empirical mode decomposition. Background technique [0002] After the diversification and complexity of electric loads, fast real-time detection and online monitoring and tracking of transient signals have become new needs. The traditional detection of steady-state harmonics is gradually developing into the detection of unsteady-state harmonics. The detection algorithm also tends to develop in the direction of complexity and intelligence. The traditional function analysis method is relatively simple and cannot adapt to all complex situations. [0003] At present, in the application of harmonic detection, Fourier transform, wavelet transform and empirical mode decomposition are the main signal processing techniques. The traditional Fourier transform-based signal processing technology tr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R23/16
CPCG01R23/16
Inventor 孙曙光庞毅刘建强齐玲张强丁铭真田朋纪学玲王佳兴
Owner HEBEI UNIV OF TECH
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