Phase difference measuring method based on improved windowing discrete Fourier transform

Abstract

The invention provides a phase difference measuring method based on improved windowing discrete Fourier transform. The phase difference measuring method includes the first step of collecting two periodic signals to be measured, the second step of analyzing the collected periodic signals to digital signals, the third step of carrying out windowing processing on the digital signals by constructing a 4-step Blackman-Harris window, and carrying out FFT spectral analysis on the signals subjected to windowing processing to obtain signal frequency spectrums, extracting fundamental wave parameters and respectively calculating initial phase angles of the periodic signals to be measured, and the fourth step of correcting phase positions of useful frequency spectrums according to a discrete spectrum correction method so as to calculate the phase differences of the periodic signals to be measured. The phase difference measuring method can effectively solve the problems that a time domain of a DFT algorithm is cut off, the introduced spectrums are revealed, and spectral analysis has bigger errors caused by the picket fence effect, overcomes the defects of spectrum leakage and lower frequency resolution in an interpolation method, improves the frequency resolution, and finally achieves the high-precision measurement of the phase differences.

Description

technical field [0001] The invention belongs to the field of power systems, in particular to a phase difference measurement method based on improved windowed discrete Fourier transform. Background technique [0002] NI's CompactRIO is a reconfigurable embedded control and acquisition system, including a built-in embedded controller, programmable FPGA and small, rugged and hot-swappable industrial I / O modules, helping researchers quickly implement Custom design, prototyping and release of measurement and control systems. In addition, it accepts programming through the NI LabVIEW graphical programming tool. Using the basic I / O functions of LabVIEW FPGA, users can directly access the input and output circuits of each I / O module of the CompactRIO hardware. All I / O modules contain built-in interfaces (such as screw terminal, BNC, or DSUB connectors), signal conditioning, conversion circuitry (such as ADC or DAC), and optional isolation shields. This design makes the low-cost ar...

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Problems solved by technology

[0024] In view of the defects or deficiencies in the prior art, the present invention aims to propose a phase difference measurement method based on the improved windowed discrete Fourier transform, which can effectively solve the spectrum leakage caused by the time domain truncation of the DFT algorithm and the spectrum analysis caused by the fence effect The problem of large errors and the shortcomings of spectrum leakage and low frequency resolution in its improved interpolation method

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