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Harmonic wave detection method based on DFT

A discrete Fourier and harmonic detection technology, applied in spectrum analysis/Fourier analysis, etc., can solve problems that affect the accuracy of harmonic detection, slow dynamic response characteristics, and poor detection of low-order harmonics

Active Publication Date: 2018-01-26
CHENGDU SIWI POWER ELECTRONICS TECH
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Problems solved by technology

The lower the LPF cut-off frequency, the higher the harmonic detection accuracy, but the dynamic response characteristics are too slow; the LPF cut-off frequency is too high, the low-order harmonic detection effect will be worse, and the harmonic detection accuracy will be affected, and this method cannot be realized Detection of Single Harmonics

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  • Harmonic wave detection method based on DFT
  • Harmonic wave detection method based on DFT
  • Harmonic wave detection method based on DFT

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Embodiment Construction

[0033] The specific embodiments of the present invention are described below so that those skilled in the art can understand the present invention, but it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, as long as various changes Within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concept of the present invention are included in the protection list.

[0034] refer to figure 1 , figure 1 Shows the flow chart of the harmonic detection method based on discrete Fourier transform; as figure 1 As shown, the harmonic detection method 100 includes step 101 to step 105 .

[0035] In step 101, the three-phase current on the power grid side of the three-phase four-wire parallel active power filter system is collected under the collection within the set period, and the AD chip is ...

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Abstract

The invention discloses a harmonic wave detection method based on discrete Fourier transform (DFT). The harmonic wave detection method based on DFT is characterized by comprising steps that a three-phase current of a power grid side is acquired in a set period, and discrete processing on the acquired three-phase current is further carried out; fundamental wave active current amplitude of the three-phase current and a calculation model of fundamental wave reactive current amplitude are constructed; DFT positive transformation of the acquired three-phase current of the power grid side is carriedout through a window sliding iteration method to respectively acquire the fundamental wave active current amplitude of the three-phase current and the fundamental wave reactive current amplitude; fundamental wave active current positive sequence components of the three-phase current are calculated through employing coordinate transformation; a detection three-phase harmonic wave current is calculated according to the acquired three-phase current and the fundamental wave active current positive sequence components.

Description

technical field [0001] The invention relates to the technical field of digital signal processing, in particular to a harmonic detection method based on discrete Fourier transform. Background technique [0002] In the design of parallel active power filter system (APF), it is necessary to compensate the grid side current to realize power factor correction. The usual method is to detect the fundamental wave component of the grid side current, and then compare the grid side current with the fundamental wave current Subtracting each other, the harmonic current is obtained as the current command signal to generate the PWM switching signal. Harmonic detection technology is the key to solving problems in actual engineering development. [0003] The current traditional harmonic detection method (ip-iq method) is based on the theory of instantaneous reactive power, sampling the three-phase network side current i a i b i c , get active current component i through park transformati...

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Application Information

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IPC IPC(8): G01R23/16
Inventor 何翔周洁琳王一丁罗润陈朝滨
Owner CHENGDU SIWI POWER ELECTRONICS TECH
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