Abstract
In order to further improve the calculation accuracy of the windowed fast fourier transform (FFT) interpolation algorithm, this study proposes a four-order Hanning self-multiplication window, and based on this new window function, four kinds of windowed FFT interpolation algorithms for harmonic analysis have been derived, include single-spectrum-line interpolation, double-spectrum-line interpolation, triple-spectrum-line interpolation and four-spectrum-line interpolation. Using these four harmonic analysis algorithms, the amplitude, phase and frequency of the fundamental and harmonic in the measured voltage and current signal can be obtained, and then the fundamental and harmonic energy can be calculated accurately by using the energy metering equation. The simulation results show that the window function has better main lobe and side lobe performance, which can effectively suppress the influence of spectrum leakage and fence effect, so based on this window function, the four harmonic analysis and energy metering algorithms can inhibit the effect of fundamental frequency fluctuation, and with the number of spectrum lines increasing, the computing accuracy of the algorithm is improved.
Highlights
More and more non-linear dynamic power loads are being put into use in power supply systems, like electrified railways, electric arc furnaces etc., which produce a lot of power harmonics, resulting in the supply of current and voltage waveform distortion
The double-spectrum-line interpolation (DSLI), triple-spectrum-line interpolation (TSLI) and four-spectrum-line interpolation (FSLI) algorithms based on this new four-order Hanning selfmultiplication window (FHSMW) can be proposed to harmonic analysis and energy metering
The Hanning window, Blackman window, Blackman–Harris window and the new FHSMW are applied to the four-spectrum-line interpolation algorithm to calculate the energy metering
Summary
More and more non-linear dynamic power loads are being put into use in power supply systems, like electrified railways, electric arc furnaces etc., which produce a lot of power harmonics, resulting in the supply of current and voltage waveform distortion. In order to further improve the computational accuracy of the windowed FFT interpolation algorithm, this paper tries to design a novel five-item cosine combination window function with a narrow main-lobe width, a lower side-lobe peak level and a faster side-lobe roll-off rate based on the widely used Hanning window function. Based on the new window function, the four kinds of harmonic analysis and energy metering algorithms of SSLI, DSLI, TSLI and FSLI are derived separately, which can greatly improve the computing accuracy of the fundamental and harmonic energy metering.
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