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Power system mesomeric state harmonic wave and/or inter-harmonic wave measuring method

A technology for steady-state and harmonic components of power systems, applied in spectrum analysis/Fourier analysis, etc., can solve problems such as difficult to distinguish signal components, decreased frequency resolution, and unavoidable measurement errors

Inactive Publication Date: 2009-02-18
WUHAN UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the case of fundamental wave component frequency fluctuations, it is difficult for the FFT algorithm to avoid measurement errors caused by frequency leakage and fence effects caused by asynchronous sampling
The Prony waveform fitting method is very sensitive to noise, and the amount of calculation is large and the effect is not ideal in practical applications.
When wavelet transform is applied to harmonic and interharmonic measurements, the frequency resolution decreases due to the wide measurement frequency band of harmonic and / or interharmonic components with higher frequencies, and it is difficult to distinguish two signal components with similar frequencies
The harmonic and / or interharmonic measurement method based on support vector machine has a large amount of calculation and low measurement accuracy, and the effect is not ideal in practical application

Method used

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  • Power system mesomeric state harmonic wave and/or inter-harmonic wave measuring method

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Embodiment Construction

[0049] The implementation process of the power system steady-state harmonic and / or interharmonic measurement method combined with the least square method and the complex band-pass filter is divided into two steps:

[0050] (1) First, the frequency resolution in the least squares model is set to 1 Hz, and the least squares method is used to preliminarily measure the possible steady-state harmonics and / or the number of interharmonic components and the approximate frequency f of each component c ;

[0051] (2) Then, for each signal component, with its f c is the center frequency, [f c -1Hz, f c +1Hz] is the passband (that is, the modulation parameter ω in formula 4 n take f c , the scale factor a is taken as 0.112526) to construct a CBPF, using the above-mentioned complex bandpass filtering algorithm to accurately identify the existence of the signal component and measure its frequency and amplitude.

[0052] The following simulation examples can illustrate the implementat...

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Abstract

The invention relates to a novel high precision frequency and amplitude measuring method for steady-state harmonic and / or inter-harmonic component in power system. The method of measuring the power system steady-state harmonic and / or inter-harmonic component comprises two steps: firstly, the number and the approximate frequency of the steady-state harmonic and / or inter-harmonic component which can possibly exist in the voltage waveform and current waveform of the power system are primarily measured through the least square method by using the resolution at 1Hz; and then multiband pass filtering is performed on each signal component to accurately judge the number of the steady-state harmonic and / or inter-harmonic component and to measure the frequency and amplitude of each component. The measuring method can swiftly and accurately measure the frequency and amplitude parameter of the steady-state harmonic and / or inter-harmonic component in the voltage waveform and the current waveform of the power system while not be affected by the frequency fluctuation of the power system(namely, nonsynchronous sampling ), and can improve the efficiency of measuring the steady-state harmonic and / or inter-harmonic and reduce the amount of calculation.

Description

technical field [0001] The invention belongs to the field of steady-state harmonic and / or interharmonic measurement of power systems. technical background [0002] With the rapid development of modern industrial technology and information industry, the requirements for power quality of various electrical equipment are increasing day by day. On the other hand, with the extensive use of electrical equipment with nonlinear characteristics, including power electronic switch type, ferromagnetic saturation type, arc type, etc., the problem of harmonic pollution in power systems has become increasingly serious. Harmonics and interharmonics (that is, signal components with non-integer multiples of the fundamental frequency) cause various hazards or effects on the power system, such as additional loss and heat generation of rotating motors, shortening service life; resonant overvoltage, causing electrical components and equipment failure and loss; electric energy measurement error; ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R23/16
Inventor 林涛曹健徐遐龄
Owner WUHAN UNIV
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