Three-phase harmonic electric energy metering method and device based on combined window multi-spectral line FFT

Abstract

The invention discloses a three-phase harmonic electric energy metering method and device based on a combined window multi-spectral line FFT. The method comprises the following steps of S1, collectingvoltage and current signals in a power grid, converting into a digital signal and outputting; and S2, using a combination window to carry out windowing FFT processing on the signal output in the stepS1 and carrying out harmonic analysis based on a multi-line spectrum interpolation, calculating and acquiring the parameters of a fundamental wave and each subharmonic, and calculating the fundamental wave and harmonic electric energy according to the calculated parameters of the fundamental wave and each subharmonic. In the invention, based on combined window multi-spectral FFT, three-phase harmonic electric energy detection and metering are realized, FFT spectrum leakage and a fence effect can be reduced, and the precision of harmonic dynamic detection and metering and a spectral resolutionare increased.

Description

technical field [0001] The invention relates to the technical field of three-phase harmonic electric energy detection and measurement, in particular to a three-phase harmonic electric energy measurement method and device based on combined window multispectral FFT. Background technique [0002] In the current smart grid environment, due to the extensive application of a large number of power electronic equipment and other impact and nonlinear loads, a large number of harmonic distortion interferences are generated in the power grid, which poses a challenge to the accuracy of current electric energy measurement. Therefore, accurate harmonic detection and electric energy Metrology research is of great significance to the current electric power industry. [0003] At present, the following methods are mainly used for the detection and measurement of harmonics in the power grid system: [0004] 1. The method based on the theory of instantaneous reactive power, this type of method...

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Problems solved by technology

[0004] 1. The method based on the theory of instantaneous reactive power, this type of method can effectively detect the grid harmonics when the grid voltage is unbalanced, and the delay is good, but its accuracy is easily affected by high-order filters, and the amount of calculation is relatively large ,higher cost

[0005] 2. The method of harmonic detection based on wavelet transform, this type of method can realize the measurement of sub-frequency bands and the extraction of time-domain signal features, but the real-time performance is poor and the amount of calculation is large

[0006] 3. Harmonic detection method based on neural network. This type of method mainly includes three parts: constructing neural network, determining autonomous learning algorithm and selecting samples based on neural network harmonic detection. It has strong adaptability and learning ability, but this Most of the class methods are currently in the research stage, the implementation is relatively complicated, and it is not easy to apply in practice

However, since the current windowed interpolation FFT harmonic analysis method is usually based on the bispectral interpolation method, it only interpolates the maximum spectral line and the sub-maximum spectral line near the frequency to be obtained, but in fact the peak spectral line near the peak spectral line The three or more spectral lines in the spectrum all occupy relatively large weights, and the accuracy and spectral resolution of harmonic analysis using only bispectral interpolation are still not high.

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