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DFT harmonic detection method without accumulated error sliding window

A technology of accumulative error and harmonic detection, applied in the direction of spectrum analysis/Fourier analysis, etc., can solve the problems of sub-harmonic detection and large amount of calculation, and achieve the effect of simple implementation and avoiding error accumulation

Inactive Publication Date: 2015-07-01
SICHUAN HOUTIAN TECH
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Problems solved by technology

The harmonic detection method based on the time domain is a real-time detection method, and generally has a fast dynamic response speed, but there is a contradiction between sub-harmonic detection and a large amount of calculation

Method used

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  • DFT harmonic detection method without accumulated error sliding window
  • DFT harmonic detection method without accumulated error sliding window
  • DFT harmonic detection method without accumulated error sliding window

Examples

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Embodiment

[0038] figure 1 It is a block diagram of the detection process of the hth harmonic.

[0039] For ease of description, this embodiment takes the single-phase load current as an example to describe specific methods for extracting the 3rd, 5th, 7th, and 11th order harmonic commands of the single-phase load current x(t).

[0040] In this example, if figure 1 As shown, extracting the h order harmonic instruction includes the following steps:

[0041] (1), create a sine table, divide 0~2π into 200 (assuming that the number of sampling points in a fundamental wave cycle is 200) equal parts, calculate the sine value of the corresponding angle, and establish a sine table of 200 points accordingly;

[0042] (2) Sampling the grid voltage signal and synchronizing the grid voltage phase θ through digital phase-locked loop technology;

[0043] (3), sample the single-phase load current signal x(t), and then perform DFT forward transformation on the single-phase load current signal x(t) th...

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Abstract

The invention discloses a DFT harmonic detection method without an accumulated error sliding window. The DFT harmonic detection method includes: collecting voltage signals of a power grid, and utilizing digital phase-locked loop technology to enable voltage of the power grid to be synchronous; performing DFT forward transformation on collected load current signals x(t) through a sliding window iteration method to respectively acquire x-axis and y-axis components; determining instruction signals of hth harmonic waves, and utilizing DFT reverse transformation to extract each harmonic instruction. By the DFT harmonic detection method, the problem of extraction of realtime harmonic instructions of an active power filter is solved, and each harmonic component can be detected accurately and quickly to guarantee realtime compensation effect of the active power filter.

Description

technical field [0001] The invention belongs to the technical field of digital signal processing, and more specifically relates to a DFT harmonic detection method without cumulative error sliding window. Background technique [0002] With the development of the power system, nonlinear loads have been applied on a large scale, and they inject a large number of harmonics into the power grid, which makes the voltage and current waveform distortion of the power system more and more serious, seriously affecting the power quality and power safety. Therefore, harmonic detection and suppression have great practical and economic significance. [0003] At present, the harmonic detection methods in the power system can be roughly divided into two categories: detection methods based on the frequency domain and detection methods based on the time domain. Detection methods based on frequency domain are based on Fourier transform, including Fast Fourier Transform (FFT), Discrete Fourier T...

Claims

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Application Information

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IPC IPC(8): G01R23/16
Inventor 王敏陆明龙唐德炜陈永祥郑国彬秦勇谢川郑宏
Owner SICHUAN HOUTIAN TECH
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