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A harmonic detection method

A harmonic detection and harmonic technology, applied in the field of harmonic detection, can solve problems such as unknown

Inactive Publication Date: 2016-04-06
BEIJING UNIVERSITY OF CIVIL ENGINEERING AND ARCHITECTURE
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  • Abstract
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  • Application Information

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Problems solved by technology

However, since this method is a calculation after the number of sampling points reaches N points, the total time for sampling N points (determined according to the calculation sequence length and sampling frequency) is t 1 The harmonic components within ms cannot be known, with t 1 ms time delay
Therefore, this harmonic detection method also has certain limitations.

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Embodiment approach

[0060] According to one embodiment of the present invention, the pq detection includes:

[0061] The three-phase current i a i b i c The current component i in the αβ coordinate system is obtained by αβ transformation α i β ;

[0062] The instantaneous active power p and reactive power q are obtained by pq transformation, and then the high-order waveform is filtered out by a low-pass filter to obtain the fundamental active power and reactive power in,

[0063] pq transforms to: p q = C p q i α i β , C p q ...

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Abstract

The invention discloses a harmonic detection method comprising the following steps: harmonic waves are detected on the basis of the transient reactive power theory; current sampling is carried out on n points of the harmonic waves to obtain an arithmetic mean value Ihm of the currents; after specific time, current sampling is again carried out on the n points of the harmonic waves to obtain the arithmetic mean value Ihm' of the currents; the difference between the Ihm and the Ihm' is calculated to obtain an absolute value K, wherein when K is in a convergence threshold value, the harmonic wave detection method is converted, and harmonic waves are detected on the basis of a fast Fourier transform method to detect the harmonic waves; and when the k is outside the convergence threshold value, the harmonic waves are further detected on the basis of the transient reactive power theory. The harmonic detection method of the invention solves the problem that higher harmonic waves cannot be detected in harmonic detection on the basis of the transient reactive power theory and accordingly proportions of harmonic components of specific times cannot be known. Besides, the problems of time delay, that is, poor performance in real-time performance, in detection of harmonic waves on the basis of the fast Fourier transform method can be solved.

Description

technical field [0001] The invention relates to a harmonic detection method. Background technique [0002] The safe and effective operation of the power grid can improve industrial production efficiency and people's living standards. Usually, the supply goal of electric energy is to provide users with a sinusoidal voltage signal of standard frequency. However, in recent years, along with the substantial increase of nonlinear loads in industrial production, nonlinear power electronic devices have been widely used. Therefore, there is a huge deviation between the actual waveform of voltage and current and the standard sine waveform, resulting in huge waveform distortion. We are used to calling this type of waveform distortion harmonics. These waveform distortions have seriously affected the industry. Power quality in production and daily life. [0003] In recent years, with the substantial increase of nonlinear loads in industrial production, a large number of applications ...

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Application Information

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IPC IPC(8): G01R23/16
CPCG01R23/16
Inventor 张雷廖春成王磊李经强郭亮张淑静刘晨曦高日
Owner BEIJING UNIVERSITY OF CIVIL ENGINEERING AND ARCHITECTURE