Frequency domain interpolation electric power harmonic wave analysis method based on discrete Fourier transform

Abstract

The invention discloses a frequency domain interpolation electric power harmonic wave analysis method based on discrete Fourier transform. The method comprises the following steps: (1) conducting time domain continuous signal discretization; (2) selecting an appropriate cosine-class window to weight a discrete sampling sequence according to measuring requirements; (3) performing fast Fourier transform on the sequence; (4) finding the two longest spectral lines close to harmonic waves in the form of spectrum peak searching, and calculating a spectrum value ratio between the two lines; (5) obtaining a frequency deviation according to a Newton interpolation method; and (6) further solving the amplitude, frequency and initial phase of sub-harmonic waves on the basis of the obtained frequency deviation. A fast interpolation based on table look-up is independent of a window function. The method is universally applied, and can be combined with any window function to conduct harmonic wave analysis. Meanwhile, no complex operation exits, the computational complexity is low, and the method is easy to realize in an embedded system.

Description

technical field [0001] The invention relates to a frequency-domain interpolation power harmonic analysis method based on discrete Fourier transform, which belongs to the field of power system harmonic measurement. Background technique [0002] With the development of intelligent power grid, more and more distributed power sources are connected to the grid, which makes the harmonic pollution more and more serious, and makes the harmonic problem more complicated. Accurate harmonic measurement is the prerequisite for the implementation of management and control of harmonics in the power grid. Therefore, harmonic measurement technology has received extensive attention. [0003] At present, researchers have proposed many methods for harmonic parameter estimation. Among these methods, the DFT-based spectrum analysis method is currently the most widely used method for estimating harmonic parameters in power systems. The physical meaning of the DFT method is clear, and FFT improve...

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Problems solved by technology

However, among these windowed interpolation methods, only the interpolation method based on the Rife-Vincent (I) window has an analytical solution between the frequency deviation and the spectral value ratio, and other forms of windowed interpolation methods can only be solved by solving the higher-order equation , iteration and other methods to obtain the approximate solution of the frequency deviation, solve high-order equations or iterative operations, which greatly increases the amount of calculation in the process of harmonic analysis and affects the practical application of related methods

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