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Harmonic analysis algorithm combining fast Fourier transform (FFT) and nonlinear least square

A least square method and least square technology, applied in the field of harmonic analysis of power grid signals, to achieve the effect of improving calculation efficiency and frequency resolution

Inactive Publication Date: 2012-08-15
CHONGQING UNIV
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Problems solved by technology

[0004] At the same time, because the harmonic model based on FFT is a nonlinear model, the traditional least square method can only solve linear problems, that is, only the amplitude parameters can be obtained.

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  • Harmonic analysis algorithm combining fast Fourier transform (FFT) and nonlinear least square
  • Harmonic analysis algorithm combining fast Fourier transform (FFT) and nonlinear least square
  • Harmonic analysis algorithm combining fast Fourier transform (FFT) and nonlinear least square

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example

[0058] Embodiments of the present invention are further described below.

[0059] Calculation example 1: Take the harmonic grid signal model as:

[0060] y ( t ) = sin ( 2 π f 0 t + π 12 ) + 0.005 sin ( 4 π f 0 t + 5 π 6 ) + 0.01 sin ( 6 π f 0 t + 77 * π 180 )

[0061] Amo...

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Abstract

The invention discloses a harmonic analysis algorithm combining fast Fourier transform (FFT) and nonlinear least square. The harmonic analysis algorithm is applied in the field of harmonic analysis of power grids, and can realize accurate calculation of frequency, amplitude and phase of power grid signals. The technical scheme (1) provides a method for calculating initial parameters of harmonic by using FFT and establishing a harmonic model, and (2) provides a nonlinear least square method for solving the parameters of the harmonic model. The algorithm has the advantages that influence of data length in no-parameter harmonic analysis on resolution is avoided, and the frequency resolution is improved; the structure and the initial parameters of the model are provided by the FFT, the parameter modeling problem of the least square is solved, and the initial values of the parameters are provided; by proper initial value selection, the initial value sensitivity of the iterative algorithm is reduced, and the iteration step is greatly reduced, so that the calculation efficiency is improved; and the parameter calculation precision of the nonlinear least square algorithm is further higher than that of a Hanning window interpolation method.

Description

technical field [0001] The invention relates to a high-precision harmonic analysis method for stationary periodic signals, including a fast Fourier transform (Fast Fourier Transform, FFT) method for preliminary estimation of harmonic parameters and a nonlinear minimum method for calculating harmonic parameters quadratic algorithm. The invention belongs to the field of harmonic analysis of grid signals. Background technique [0002] With the wide application of nonlinear equipment such as power electronics in power systems, harmonics and interharmonics are increasing, which seriously affects the safe operation of power systems. The analysis of harmonics and interharmonics is of great significance to power systems. The current harmonic analysis is mainly realized by sampling and digital processing of the power grid signal. Considering the asynchronous sampling caused by the frequency fluctuation of the power grid, direct spectrum analysis will seriously affect the calculation...

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Application Information

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IPC IPC(8): G01R23/16
Inventor 张淮清付志红侯兴哲李春燕张谦
Owner CHONGQING UNIV
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