Complex harmonic detection and analysis method of four-spectral-line interpolation FFT based on five-item Rife-Vincent(I) window

Abstract

A complex harmonic detection and analysis method of four-spectral-line interpolation FFT based on a five-item Rife-Vincent(I) window is disclosed. The method comprises the following steps of carryingout discrete sampling on a signal containing multiple complex harmonics to obtain a discrete sequence signal; adding the five-item Rife-Vincent(I) window to the sampled discrete sequence signal to obtain the discrete sequence signal with the window; carrying out a discrete Fourier transform on the obtained discrete sequence signal with the window to obtain a discrete harmonic signal spectrum value; according to the obtained harmonic signal spectrum value, finding four spectral lines near each harmonic frequency point; and according to the four spectral lines near the harmonic frequency point,establishing a spectrum relation of the four spectral lines, acquiring an offset between an actual spectral line value and a theoretical spectral line value, deriving a correction formula of a harmonic parameter, and then calculating the harmonic parameter after four-spectral-line interpolation correction. Compared with an existing power grid harmonic detection method, the method of the inventionhas better performance, and harmonic precision in the method of the invention is greatly increased.

Description

technical field [0001] The invention belongs to the technical field of detecting multiple complex harmonics of a power grid, and in particular relates to a complex harmonic detection and analysis method based on a four-spectrum line interpolation FFT of a five-term Rife-Vincent (I) window. Background technique [0002] Nowadays, with the rapid development of the power grid, various new equipments have been applied to the power grid one after another, especially the wide application of power electronic devices and the large increase of nonlinear loads, which make the voltage and current characteristics of the power system more and more complicated, and the harmonic pollution of electric energy is becoming more and more serious. Serious, it will endanger the security of the system. Therefore, accurate measurement of the harmonic content in the power grid can provide an effective scientific basis for the control of harmonics and maintain the safety of the system. At present, t...

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Problems solved by technology

[0004] The patent literature (CN 105353215) proposes a harmonic detection method based on the Nuttall window four-line interpolation FFT. Since the sidelobe attenuation rate of the Nuttall window is small, it cannot well suppress the spectral leakage caused by the harmonic measurement. Interference, so the measurement accuracy of multiple complex harmonics in the power grid needs to be improved

Moreover, the patent only measures odd harmonics, not even harmonics. At the same time, the amplitude parameters of harmonic signals are relatively large, which cannot reflect the measurement accuracy of the algorithm for weak amplitude parameters.

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