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Method for estimating power harmonic wave parameter by using power gravity center of symmetric window function

A technology of symmetrical window function and power harmonics, applied in spectrum analysis/Fourier analysis, etc., can solve the problem of increased calculation amount and achieve the effect of reduced calculation amount

Inactive Publication Date: 2012-06-13
CHINA UNIV OF MINING & TECH
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Problems solved by technology

Many scholars use the window interpolation method to effectively improve the accuracy of harmonic estimation [1~5] , but as the order of the interpolation correction curve fitting function increases and the number of harmonics contained increases, the accuracy of harmonic estimation improves and the amount of calculation increases greatly

Method used

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  • Method for estimating power harmonic wave parameter by using power gravity center of symmetric window function
  • Method for estimating power harmonic wave parameter by using power gravity center of symmetric window function
  • Method for estimating power harmonic wave parameter by using power gravity center of symmetric window function

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Embodiment 1

[0024] Embodiment 1: 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 after appropriate signal conditioning The incoming signal sample entry.

[0025] Technical scheme of the present invention takes the following steps to realize:

[0026] Step a. Take the sampling period as Sampling the power signal to be analyzed, that is, voltage or current signal: , according to the measurement accuracy requirements, select the appropriate symmetric window function Truncating the sampled power signal gives: , N is the data truncation length of the window function, and the symmetrical window function is Hanning, Hamming, Black, Leif or Nuttall;

[0027] A multi-frequency power (voltage or current) harmonic signal can be represented as follows...

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Abstract

The invention provides a method for estimating a power harmonic wave parameter by using a power gravity center of a symmetric window function, belonging to an analysis and automatic monitoring method of electric network voltage and current waveform distortion. The method comprises the following steps: using the symmetric window function to cut a sampled power harmonic wave signal, and carrying out fast Fourier transform (FFT for short) on a cut signal; calculating fundamental wave frequency and frequency of each subharmonic according to the power gravity center of the symmetric window function; calculating a phase of each corresponding subharmonic by using the calculated frequency of each subharmonic, and calculating an amplitude of each sub-power harmonic through the Pasival theorem. Compared with other windowing FFT interpolation correction analysis methods, the method of the present invention has an obvious advantage at calculation time consumption, is suitable for being used for an embedded system and a digital signal processor (DSP), and is a very practical algorithm.

Description

technical field [0001] The invention relates to an analysis and automatic monitoring method of grid voltage and current waveform distortion, in particular to a method for estimating power harmonic parameters of a symmetrical window function power center of gravity. 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 spectrum is to ensure the synchronous sampling and truncation of the entire period of the signal. The actual p...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R23/16
Inventor 唐轶陈奎杨洛陈雷渐伟张跃尹远谷露孙瑜欣于正华
Owner CHINA UNIV OF MINING & TECH
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