FFT power harmonic detection method for bidirectional interpolation synchronization sampling sequence

Abstract

The invention discloses an FFT power harmonic detection method for a bidirectional interpolation synchronization sampling sequence, comprising: step 1, a mutual inductor samples a harmonic signal, a discrete signal x(n) is obtained, and the signal x(n) is subjected to filtering processing to acquire a fundamental wave signal x0(n); step 2, fundamental wave signals of ten continuous cyclic waves are taken as sampling data; step 3, the sampling data are subjected to forward Newton interpolation, and moment positions when an amplitude value of the sampling data exceeds a threshold value a for the first time and the twenty first time are acquired, and respectively marked as tstart and tend; step 4, by taking equal diversion points between the moment positions tstart and tend as interpolation points, the sampling data are subjected to reversed Newton interpolation, thus acquiring signal amplitude values of the various interpolation points, namely acquiring the synchronization sampling sequence; step 5, the synchronization sequence is subjected to fast Fourier transform. The FFT power harmonic detection method can be used for quickly and accurately detecting signal harmonic components and continuously detecting the detected signals for a long term, and has good timeliness.

Description

technical field [0001] The invention relates to the technical field of harmonic detection in electric power systems, in particular to an FFT electric harmonic detection method of bidirectional interpolation and synchronous sampling sequences. Background technique [0002] The large increase of nonlinear loads in the power system, especially the wide application of power electronic devices, increases the harmonic components in the power grid and seriously deteriorates the power quality. The occurrence of harmonics in the distribution network may not only cause resonance in the power grid, but also increase the loss of the motor and transformer, aggravate the aging of the power cable, and shorten the life of the power cable. The rapid and accurate detection of harmonic components will be beneficial to the analysis and treatment of power quality. Fast Fourier transform has become the most important method of power grid harmonic analysis because of its mature theory and easy em...

AI Technical Summary

Problems solved by technology

[0004] However, although fast Fourier analysis after windowing can effectively reduce spectrum leakage, due to the large number of side lobes in the frequency domain of the window function, the spectrum leakage cannot be well suppressed, and the side lobes with large amplitude-frequency response The lobes interfere with the detection of weaker frequency components in the original signal

However, the window function with excellent side lobe characteristics has the disadvantages of complex interpolation correction formula and long time-consuming process of spectral line detection, which seriously affects the timeliness.

Images