APF harmonic detection method based on spectrum leakage correction algorithm

Abstract

The invention discloses an APF harmonic detection method based on a spectrum leakage correction algorithm. Based on the traditional discrete Fourier transform, the method uses the signal truncation length as an independent variable, extends the classical one-dimensional amplitude spectrum into two dimensions, provides a new way for signal spectrum characterization, and adopts a spectrum leakage correction algorithm based on the minimum error to achieve accurate estimation of the frequency, amplitude and phase. Compared with the prior art, the method of the invention obtains N closest to the integral cycle truncation through the two-dimensional spectrum, on this basis, obtains approximate accurate estimates of the signal frequency, amplitude and phase based on the minimum error theory by taking the spectral value constructed by sinc as a real spectrum, and has the advantages of small error and easy implementation.

Description

technical field [0001] The invention relates to the technical field of harmonic detection, in particular to an APF harmonic detection method based on a spectrum leakage correction algorithm. Background technique [0002] APF detects the fundamental reactive current, negative sequence current and harmonic current required by the load, and controls the inverter output to track the detected current, so as to achieve comprehensive compensation for load reactive power. The detection method of the compensation command current determines the detection accuracy of the harmonic current, which in turn affects the current compensation effect. Therefore, harmonic detection technology has always been the key research content in the field of harmonic compensation, and the research on compensation command current detection method mainly revolves around two aspects of detection speed and accuracy. [0003] At present, the detection methods of compensating command current are mainly detecti...

AI Technical Summary

Problems solved by technology

[0007] The root cause of spectrum leakage caused by Fourier transform for spectrum analysis is that the input signal cannot accurately and completely represent the analyzed signal, and an error occurs in the output. Although this error can be solved by adding a suitable window function or extending the time as described above The window can be improved, however, the role of the window function is very limited, it can only improve but not eliminate the spectral leakage

Although various interpolation algorithms based on DFT improve the accuracy of frequency estimation, these methods are at the cost of increased calculation or complex algorithms

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