Detection method of harmonics/inter-harmonics

A detection method and harmonic technology, applied in the direction of measuring devices, measuring electrical variables, instruments, etc., can solve the problems of large amount of calculation, precision is sensitive to AR model order and noise, noise sensitivity, etc., to achieve simple algorithm and high calculation volume Small, easy-to-achieve effects

Active Publication Date: 2017-05-17
PANZHIHUA UNIV
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Problems solved by technology

The autoregressive-moving average model spectrum estimation method can significantly improve the frequency resolution, but its accuracy is sensitive to the order of the AR model and noise; the Prony method can directly extract the characteristic quantity of the signal for analysis, but it is computationally intensive and sensitive to noise

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  • Detection method of harmonics/inter-harmonics
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  • Detection method of harmonics/inter-harmonics

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Embodiment Construction

[0023] Such as figure 1 The detection method of the shown harmonic / interharmonic of the present invention includes:

[0024] A. Channelization design: divide the harmonics / interharmonics and noise in the input signal into K channels of different frequency bands through a filter bank composed of filters with different center frequencies. In this embodiment, an FIR filter (finite-length unit impulse response filter) is adopted. The unit impulse response of the D-order low-pass filter is: h 0 [n]={h[0]...h[D-1]}, other filters can be generated by the frequency shift of this low-pass filter. The center frequency of the filter of the k-th channel in the K-channel channelization structure is: ω k =2πk / K, the unit impulse response of the bandpass filter is: The passband boundary frequency of the filter is ω p = π / K; the stop band boundary frequency is ω s =2π / K. frequency at The harmonics and interharmonics of will fall into the kth channel.

[0025] Due to the uncertainty o...

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Abstract

The invention relates to detection methods of harmonics / inter-harmonics. The detection methods of harmonics / inter-harmonics comprise the following ones: A. distributing signals to different channels 50% of which overlap, and extracting in M times convolution of a filter corresponding to the harmonics / inter-harmonics from the channels; B. performing windowed Fourier transform on the output frequency spectrum after the M times extraction of the harmonics / inter-harmonics; C. calculating power spectrum; D. searching the power spectrum; if the maximum of the power spectrum is more than noise power, then this signal is a harmonic / inter-harmonic, or otherwise the signal is noise; E. adjacent channels with high amplitude is the real ones where lie harmonics / inter-harmonics; F. performing approximate calculations on the points adjacent to the maximum of the power spectrum, and outputting the amplitude, the initial phase and the frequency of corrected channels. The detection methods of harmonics / inter-harmonics can carry out parallel processing on harmonics / inter-harmonics in different channels, and obviously increase real-time performance of the detection and estimation accuracy of parameters. In addition, the methods have the advantages of being easy in algorithm, small in computing load and easy to realize.

Description

technical field [0001] The invention relates to a method for detecting harmonics / interharmonics. Background technique [0002] With the wide application of electric power and electronic devices, the problem of harmonic and interharmonic distortion becomes more and more serious. The sources of harmonics mainly include two types: traditional nonlinear devices (such as transformers, electric arc furnaces, etc.) and modern power electronic nonlinear devices (such as thyristors, fluorescent lamps, etc.). The sources of interharmonic mainly include two categories: cycloconverter and period-changing load. A certain amount of harmonics / interharmonics will cause great harm to the power grid and users, mainly including: generating additional energy loss, affecting insulation conditions, shortening equipment life, and interfering with relay protection devices, measuring instruments and precision equipment , resulting in misoperation and measurement errors. [0003] Fast and accurate...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R23/165
CPCG01R23/165
Inventor 杜正聪朱家龙祝俊
Owner PANZHIHUA UNIV
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