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Method for calculating amplitude and phase of alternating current signal based on iterative Fourier transform

An iterative Fourier, alternating current technique, applied in the direction of the phase angle between voltage and current, measuring current/voltage, measuring electrical variables, etc.

Inactive Publication Date: 2012-12-12
TIANJIN ZHONGKE HUARUI ELECTRICAL TECH DEV CO LTD
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Problems solved by technology

When applying dynamic reactive power compensation technology, it is necessary to detect the fundamental wave amplitude and phase of the bus current, while the traditional method based on Fourier transform to obtain the fundamental wave amplitude and phase requires a large number of calculations at each sampling point to obtain accurate results

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  • Method for calculating amplitude and phase of alternating current signal based on iterative Fourier transform
  • Method for calculating amplitude and phase of alternating current signal based on iterative Fourier transform
  • Method for calculating amplitude and phase of alternating current signal based on iterative Fourier transform

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Embodiment

[0064] There is a load system connected to a 6.5kV bus in a steel factory. Because the load system contains power electronic equipment, the current of the load system is distorted. Through actual measurement, the following is obtained: figure 2 The A-phase current curve shown, at this time the sampling frequency f s =10000Hz, sampling period T s =0.0001s. If it is necessary to obtain the amplitude and phase of the fundamental current (that is, n=1) from the detection current, the frequency of the A-phase current signal to be extracted in this embodiment is f 1 =50Hz, the angular frequency is w 1 =2πf 1 =314.15rad / s, the number of sampling points in one cycle N = f s f n = 10000 50 = 200 .

[0065] When N≥k>0, calculate the sine function sin(w 1 kT s ) and the cosine function ...

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Abstract

The invention discloses a method for calculating the amplitude and phase of alternating current based on iterative Fourier transform, and belongs to the technical field of power supply. The method comprises the following steps of: determining sampling frequency, and initializing parameters; determining the frequency of the alternating current to be extracted; calculating a sine function and a cosine function; sampling an alternating current value; judging a sampling number, and calculating the cosine amplitude and sine amplitude of sub-harmonics of the alternating current; and obtaining the amplitude and phase of sub-harmonic current of the alternating current. Accurate fundamental current amplitude and phase can be obtained by performing addition and subtraction once on data obtained by the sampling of each time; and compared with the conventional Fourier-transform-based method, the method has the advantages that calculation processes are greatly reduced, and requirements for the high speed and accuracy of signal detection in a power system can be met.

Description

technical field [0001] The invention belongs to the technical field of electric power supply and relates to the design of a dynamic reactive compensation device in a power supply system, in particular to a method for calculating the amplitude and phase of an alternating current signal based on iterative Fourier transform. Background technique [0002] Impulse loads such as rolling mills and electric arc furnaces in the iron and steel metallurgical industry cause flicker to the grid current, so it is necessary to use dynamic reactive power compensation technology for real-time control to stabilize the bus current. When applying dynamic reactive power compensation technology, it is necessary to detect the fundamental wave amplitude and phase of the bus current, while the traditional method based on Fourier transform to obtain the fundamental wave amplitude and phase requires a large number of calculations at each sampling point to obtain precise results. Contents of the inve...

Claims

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Application Information

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IPC IPC(8): G01R19/00G01R23/16G01R25/00
Inventor 张华军陈方元褚学征尉强
Owner TIANJIN ZHONGKE HUARUI ELECTRICAL TECH DEV CO LTD
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