Method for accurately calculating and analyzing harmonic and electric energy quality

Abstract

The invention discloses a method for accurately calculating and analyzing harmonic and electric energy quality. The method comprises the following steps: selecting a detected signal sampling sequence; carrying out discrete Fourier transformation (DFT) on the sampling sequence; selecting a 3-order rapid attenuation window Nuttall; after windowing a signal, carrying out the discrete Fourier transformation; calculating to solve a phase phik; and finally, obtaining amplitude Ak, frequency fk and the phase phik of a detected signal to finish the analysis of the harmonic and the electric energy quality. According to the method, long-range leakage is eliminated by windowing, and an error, caused by the long-range leakage, is eliminated by using an interpolation algorithm; the frequency spectrum leakage caused by nonsynchronous sampling in the prior art is avoided by the method. A test comparing result shows that the frequency, amplitude and phase measurement errors of the algorithm are very small; compared with an actual measurement error, the errors can be completely ignored. With the adoption of the method, the equipment can be used as a harmonic measurement standard device capable of being used as a quality standard laboratory of a provincial-level technical supervision bureau or an electric power research institute and above.

Description

technical field [0001] The invention belongs to the field of electricity, in particular to a method for accurately calculating and analyzing harmonics and power quality. Background technique [0002] In recent years, with the rapid growth of my country's electricity demand, the development of the power industry has gradually grown, and the pace of power grid construction has continued to accelerate, the impact of harmonics on power quality has attracted more and more attention. All nonlinear loads can generate harmonic currents. The types of equipment that generate harmonics are: switch mode power supply (SMPS), electronic fluorescent lamp ballast, variable speed drive, uninterruptible power supply (UPS), magnetic core equipment and Certain household appliances such as televisions, etc. Power grid harmonics come from three aspects: first, harmonics generated by low-quality power generation; second, harmonics generated by power transmission and distribution systems; third, h...

AI Technical Summary

Problems solved by technology

The disadvantages of this algorithm are: the calculation accuracy depends on the fundamental frequency, and the calculation of the fundamental frequency needs to go through a filtering link, which affects the calculation accuracy of the fundamental frequency; because each sampling point needs to be recalculated, the calculation amount is large

As long as the selected window function and interpolation algorithm are suitable, the accuracy of the algorithm is very high. Its disadvantage is that it needs a long sampling sequence and uses the attenuation characteristics of the side lobes of the window function to eliminate long-range leakage, and its real-time performance is poor.

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