Quick detecting method for harmonic wave of electric power system

Abstract

The invention discloses a quick detecting method for a harmonic wave of an electric power system, and particularly relates to a method for detecting phase and amplitude of signals with different frequencies in the electric power system. The method comprises the following steps of (1), acquiring sampling points of which the number is at least two times of that of the harmonic waves through using two times of highest multiplied frequency as a sampling rate; (2), constructing a sine signal and a cosine signal which correspond with each harmonic wave frequency; (3), calculating a harmonic wave detecting parameter through fitting the coefficient before each sine item and cosine item; and (4), combining the coefficients in front of the sine item and the cosine item with the same frequency for obtaining the amplitude and the phase of the harmonic wave with each frequency. Compared with the prior art, the quick detecting method is advantageous in that a small volume of data are required; a result can be calculated just through the data with length of one half of that of a fundamental frequency signal; relative to an FFT (fast Fourier transform) method, a problem of frequency leakage can be prevented; and the method is compatible with clutter interference to a certain extent.

Description

Technical field [0001] The invention relates to the field of digital signal processing, and in particular to a method for quickly detecting harmonics in a power system. Background technique [0002] In recent years, people’s requirements for power quality have become higher and higher, but at the same time, the factors that cause power quality problems are also increasing. One of the influencing factors is mainly the harmonics and interharmonics in the power system. The safety, stability, and economic operation of the power system pose a potential threat, and the harm to power equipment is particularly serious. Therefore, the study of power system harmonics is particularly important, and the detection of power system harmonics is the primary task of these studies. [0003] Fast Fourier Transform (FFT) is the most commonly used method of harmonic detection, and this method needs to collect all data within at least one complete cycle of the fundamental frequency to get the correct re...

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Problems solved by technology

[0003] Fast Fourier transform (FFT) is the most commonly used harmonic detection method, and this method needs to collect all data within at least one complete period of the fundamental frequency to obtain correct results, and the FFT algorithm has the problem of energy leakage, resulting in The calculated harmonic amplitude of each frequency is quite different from the actual amplitude. In addition, the calculation process of the FFT algorithm is complicated, and real-time analysis cannot be realized.

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