Harmonic wave analysis method based on non-synchronous sampling

A technology of asynchronous sampling and harmonic analysis, applied in spectrum analysis/Fourier analysis, etc., can solve problems such as limitation, frequency tracking delay, and difficulty in accurately adjusting the sampling period

Active Publication Date: 2009-04-08
江苏中凌高科技股份有限公司
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Problems solved by technology

[0005] (1) The synchronization link is based on frequency tracking, and frequency tracking is always delayed;
[0006] (2) The DSP timer has a minimum resolution, and the accuracy of adjusting the sampling period is limited by the minimum resolution;
[0007] (3) The sampling frequency of the high-end harmonic analyzer is very high (several KHz to dozens of KHz) - the sampling period is very short (microsecond level),
[0008] It is very difficult to adjust the sampling period precisely by DSP;

Method used

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  • Harmonic wave analysis method based on non-synchronous sampling
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Embodiment Construction

[0019] A harmonic analysis method for a three-phase power grid based on asynchronous sampling is introduced in detail below in conjunction with the accompanying drawings. The steps are as follows:

[0020] 1) Store preset weight coefficients one-to-one corresponding to the signal frequency in the memory; the weight coefficient refers to subdividing the signal frequency into K discrete values ​​f within a certain range 1 , f 2 ,...,f k , for each discrete value f k Substitute into the equation FWG=I 2M+1 , and solve the corresponding weight coefficient W offline k (k=1,2,...,K);

[0021] 2) Sampling the harmonics with a constant sampling period, sampling the three-phase voltages Ua, Ub, and Uc with the corresponding voltage transformers Pta, PTb, and PTc, and sampling the three-phase currents Ia, Ib, and Ic with the current mutual inductance Cta, CTb, CTc samples, and the signal obtained after sampling is sent to the multi-channel analog-to-digital converter for analog-to-...

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Abstract

The invention relates to a harmonic analysis method based on asynchronous sampling, belonging to the field of signal harmonic detection technique. The method comprises the steps as follows: 1) a plurality of prearranged weight coefficients corresponding to signal frequencies one-to-one are sequentially memorized in a memory; 2) the harmonics are sampled under a constant sampling period; a sampling signal is output to a digital signal processor after A / D conversion; 3) the digital signal processor processes digital signals which are converted by multi-path A / D converters, and according to the frequencies, the positions of the weight coefficients needed to be invoked in the memory are determined; 4) in the digital signal processor, corresponding weight coefficients invoked in the memory is multiplied by the input digital signals, subsequently, FFT processing is carried out; and 5) the FFT-processed result is displayed or printed. The method overcomes the synchronous difference problem of the harmonic analysis, obtains real-time harmonic analysis signals with high precision, and can be applied to the signals in the fields such as machines, power, information, geology, hydrology and the like so as to carry out the harmonic analysis.

Description

technical field [0001] The present invention relates to a signal harmonic analysis method, which is suitable for harmonic analysis of 'approximately periodic signals' (such as electric power signals) with varying frequency. Background technique [0002] In fields such as machinery, electricity, information, geology, and hydrology, it is often necessary to perform harmonic analysis on signals (or waveforms), and an instrument that can perform harmonic analysis is called a harmonic analyzer (or harmonic analyzer). The main work of the harmonic analysis method includes: sampling the continuous time signal and ADC (multi-channel analog-to-digital converter) to obtain the sampling sequence, performing FFT (fast Fourier transform) on the sampling sequence to obtain the harmonic analysis results (the Amplitude and phase information), display and transmission of harmonic analysis results (communication), etc. [0003] The accuracy of the harmonic analyzer mainly depends on two aspe...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R23/16
Inventor 王柏林
Owner 江苏中凌高科技股份有限公司
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