Windowing short-time Fourier transform three-point interpolation dynamic frequency measurement method

Abstract

The invention discloses a windowing short-time Fourier transform three-point interpolation dynamic frequency measurement method, and the method comprises the following main steps: 1, carrying out the discrete sampling of a time domain continuous wave of a power grid, and obtaining an N-point sampling sequence U(n); 2, selecting a window function, employing the short-time Fourier transform, and obtaining a short-time Fourier transform matrix FSTFT(i, j) of the sampling sequence; 3, solving a spectral line k1 corresponding to the maximum value of a p-th column of the matrix, and the adjacent spectral lines k2 and k3; 4, employing a polynomial approximation method to solve a peak spectral line parameter alpha

through the spectral lines k1, k2 and k3; 5, employing a formula f<mp>=( alpha

+k1)*delta f, and solving the peak frequency f<mp> of the signal; 6, calculating a signal frequency change rate f<c-p>, determining columns which need to be added and calculated, and calculating a corresponding peak frequency f<mp>; 7, obtaining a dynamic frequency function f<m>(p) of the change of signal with time according to the peak frequency f<mp>. The method takes the windowing short-time Fourier transform as the basis, employs an interpolation method, also can carry out the analysis of the time domain of the signal while quickly measuring the frequency, is high in precision, and is simple in calculation.

Description

technical field [0001] The invention belongs to the technical field of power system frequency measurement, and relates to a dynamic frequency measurement method of windowed short-time Fourier transform three-point interpolation. Background technique [0002] Frequency is an important operating parameter of the power system and electrical equipment. The rated frequency of my country's power system is 50Hz, and the frequency deviation range specified in the "Technical Management Regulations of the Electric Power Industry" is ±0.2-±0.5Hz. The purpose is to ensure the power system. Stable operation and supply high-quality electric energy to users. Since electric energy cannot be stored, and the load changes at any time, the change of the load will cause the change of the power system frequency, and the dynamic frequency of the system directly affects the power quality and the safety and stability of the power grid operation. Frequency measurement is the basis for power system an...

AI Technical Summary

Problems solved by technology

However, the current frequency measurement method is difficult to meet the analysis requirements of the system for the time-space distribution characteristics of the frequency response, which poses new challenges to the power grid dynamic frequency analysis measurement method

[0003] The method proposed by the present invention overcomes the shortcomings that the traditional frequency measurement method is difficult to satisfy the frequency domain analysis and time domain analysis at the same time

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