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Rife-Vincent (II) window interpolation FFT (Fast Fourier Transform)-based harmonic and inter-harmonic detection method

A harmonic detection and harmonic technology, applied in the field-based, can solve problems such as unsatisfactory spectrum side lobe characteristics, large analysis errors, difficult frequency measurement and harmonic analysis, and limited suppression

Inactive Publication Date: 2013-11-20
WUHAN UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] However, due to the unsatisfactory spectral side lobe characteristics of the above window function, the suppression effect on spectrum leakage is limited, and the analysis error of the frequency, amplitude and phase of the signal in the harmonic analysis is large, and it is difficult to achieve high-precision frequency measurement and harmonics. Analysis; in the interharmonic analysis, more than 20 power frequency cycle data are needed to accurately realize the interharmonic analysis, which is difficult to meet the real-time requirements of interharmonic detection

Method used

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  • Rife-Vincent (II) window interpolation FFT (Fast Fourier Transform)-based harmonic and inter-harmonic detection method
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  • Rife-Vincent (II) window interpolation FFT (Fast Fourier Transform)-based harmonic and inter-harmonic detection method

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Embodiment 1

[0049] Harmonic detection:

[0050] Select a voltage harmonic signal x(t), such as image 3 shown.

[0051] The harmonic detection method of the present invention comprises six steps:

[0052] Step 1. With a fixed sampling frequency f s =10000Hz sampling harmonic signal x(t) to get: x(n), for its Rife-Vincent (II) window (M=11, R=10 150 ) to get the truncated signal x m (n),x m (n)=x(n)w(n)n=0...N-1, the length of the window function N=2000, the signal after sampling is as follows Figure 4 shown;

[0053] Perform Fourier transform calculation on the truncated signal, as shown in equation (9):

[0054] X m ( k ) = N 2 Σ n = 0 N - 1 ( A n / ...

Embodiment 2

[0070] Interharmonic detection:

[0071] Select a voltage signal x(t) containing interharmonics, such as Figure 5 shown.

[0072] The interharmonic detection method of the present invention comprises six steps:

[0073] Step 1. With a fixed sampling frequency f s =10000Hz sampling harmonic signal x(t) to get: x(n), for its Rife-Vincent (II) window (M=3, R=10 50 ) to get the truncated signal x m (n),x m (n)=x(n)w(n)n=0...N-1, the length of the window function N=2000, the signal after sampling is as follows Figure 6 shown;

[0074] Perform Fourier transform calculation on the truncated signal, as shown in formula (15):

[0075] X m ( k ) = N 2 Σ n = 0 N - 1 ( A ...

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Abstract

The invention provides a Rife-Vincent (II) window interpolation FFT (Fast Fourier Transform)-based harmonic and inter-harmonic detection method. The parameters of a Rife-Vincent (II) window are variable and the window function characteristics are adjustable. The parameters of the window functions can be set according to features of different analysis signals to obtain proper window function characteristics so as to realize high-accuracy detection of frequency, harmonic wave and inter-harmonic wave. The method is flexible in application and extremely high accuracy can be achieved in frequency, harmonic and inter-harmonic analysis application of a power system.

Description

technical field [0001] The invention relates to a method for measuring frequency, harmonic and interharmonic parameters, in particular to a method based on [0002] Harmonics and interharmonics detection method for Rife-Vincent (II) window interpolation FFT. Background technique [0003] The large increase of nonlinear loads in the power system, especially the wide application of power electronic devices, has caused a large number of harmonics and interharmonics in the power grid, resulting in serious deterioration of power quality. Accurate analysis of harmonic and inter-harmonic components will be beneficial to the evaluation of power quality, and necessary measures can be taken to control it. Fast Fourier transform has become the most important method for power harmonic analysis, but when FFT is used for power harmonic analysis, it is easy to produce spectrum leakage and fence effect, which leads to inaccurate calculation results of signal parameters (frequency, amplitud...

Claims

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Application Information

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IPC IPC(8): G01R23/163
Inventor 刘开培汪立乐健
Owner WUHAN UNIV
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