Method for obtaining continuous frequency spectrum interpolation power harmonic parameter of Nuttall window function

A technology of power harmonics and Nuttall windows, applied in the field of power measurement and automation

Inactive Publication Date: 2011-11-23
CHINA UNIV OF MINING & TECH
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Problems solved by technology

Many scholars have effectively improved the accuracy of harmonic estimation by using the window interpolation method [1~6], but with the increase of the order of the interpolation correction curve fitting function and the increase of the number of harmonics , the accuracy of harmonic estimation is improved and the amount of calculation is greatly increased

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  • Method for obtaining continuous frequency spectrum interpolation power harmonic parameter of Nuttall window function
  • Method for obtaining continuous frequency spectrum interpolation power harmonic parameter of Nuttall window function
  • Method for obtaining continuous frequency spectrum interpolation power harmonic parameter of Nuttall window function

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Embodiment Construction

[0032] In order to achieve the above object, the implementation of the present invention can directly use a voltage divider or obtain the busbar voltage signal of the power grid from the secondary side of the voltage transformer PT, obtain the current signal from the current transformer CT, and send the signal sampling after appropriate signal conditioning Entrance.

[0033] Step a. Sampling the voltage or current of the power signal to be analyzed, and press figure 1 The process calculates its Chirp-Z Transform or CZT value , take a natural positive integer, and then calculate the fundamental wave parameters, amplitude, frequency and phase of the power signal by formula 1, formula 2 and formula 3;

[0034] Estimate the fundamental amplitude: Formula 1

[0035] Estimate the fundamental frequency value: f 1 =(θ+k’Ф) / 2 Formula 2

[0036] Estimate the fundamental phase value: Formula 3

[0037] In the above 3 formulas: Mis the number of sa...

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Abstract

The invention discloses a method for obtaining continuous frequency spectrum interpolation power harmonic parameter of Nuttall window function, and is suitable for harmonic analysis and monitoring of voltage and current of power grid. The method comprises the following steps: performing chirp Z transform (CZT) to extract a fundamental wave signal parameter (amplitude, frequency and phase) at high precision from a power signal containing harmonic; subtracting the fundamental wave signal from the analyzed power signal and adding a cutoff power signal of Nuttall window function, and calculating the frequency spectrum of the residual signal by FFT (fast Fourier transform); calculating the frequency value of each harmonic accurately according to the frequency of the fundamental wave; and finally, interpolating the Nuttall window function in the frequency domain according to the frequency of each harmonic, and accurately calculating the parameter of each power harmonic. The method disclosed by the invention has basically equivalent estimation precision as the method for analyzing power harmonic through FFT double-spectral-line interpolation fitting with Nuttall window, while the calculation quantity is about half of the latter one.

Description

technical field [0001] The invention relates to an analysis and automatic monitoring algorithm of grid voltage and current waveform distortion, which can be used for analysis instruments and automatic monitoring devices of various grid voltage and current waveform distortions. The utility model belongs to the technical field of electric power measurement and automation. Background technique [0002] With the development of power electronics technology and devices, nonlinear loads are more and more widely used in power systems, and harmonic pollution in power systems is becoming more and more serious. Harmonics have become the main problem affecting power quality. The high-precision estimation of harmonic component parameters will be beneficial to the evaluation of power quality and the corresponding necessary control measures. [0003] Fast Fourier Transform (FFT) is the fastest tool for harmonic analysis. However, the premise of FFT to accurately analyze the frequency spe...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R23/16
Inventor 唐轶方永丽齐敦金韩智强尹远周斌杨洛张跃渐伟陈雷
Owner CHINA UNIV OF MINING & TECH
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