Voltage sag source identification method based on Hilbert-Huang transformation and wavelet packet energy spectra

A technology of voltage sag source and identification method, applied in the direction of measuring current/voltage, measuring electrical variable, measuring device, etc., can solve the problems of identification, the inability of voltage sag waveform, etc., and achieve the effect of improving identification efficiency

Inactive Publication Date: 2013-12-04
KUNMING UNIV OF SCI & TECH
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Problems solved by technology

[0007] The technical problem to be solved by the present invention is to overcome the problem that the voltage sag waveform cannot be identifi

Method used

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  • Voltage sag source identification method based on Hilbert-Huang transformation and wavelet packet energy spectra
  • Voltage sag source identification method based on Hilbert-Huang transformation and wavelet packet energy spectra
  • Voltage sag source identification method based on Hilbert-Huang transformation and wavelet packet energy spectra

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Embodiment 1

[0053] Embodiment 1: as figure 1 Shown is the power grid simulation model built using Matlab / Simulink / PSB, the transformer in the power grid T 1 , T 2 Use Y n / Y connection, T 3 , T 4 With Y / Y connection, set f s to 1000 Hz. by formula f s / 2 n+1 n is 4, the sampling time is set to 1s, and the start and end times of the voltage sag are 0.1s and 0.5s respectively. K Points were measured short-circuit, transformer T 2 Putting into operation, induction motor M 1 Start voltage signal.

[0054] The three-phase voltage signals are decomposed by EMD to obtain the IMF components of each order, which are decomposed by four-layer wavelet packets respectively, and then calculated according to formulas (1) and (2) to obtain the first n Energy percentage of each frequency band decomposed by layer wavelet packet I i (that is, the energy percentage of the 0~15th frequency band in the fourth layer), so as to give the energy spectrum diagram of the energy percentage of the ...

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Abstract

The invention discloses a voltage sag source identification method based on Hilbert-Huang transformation and wavelet packet energy spectra, and belongs to the field of electric energy quality analysis of electric power system. The method includes the steps: firstly, performing EMD (empirical mode decomposition) for a three-phase voltage signal to obtain IMF (intrinsic mode function) components; secondly, performing n-layer wavelet packet decomposition for the IMF components to obtain energy spectra of frequency bands; thirdly, setting a larger wavelet packet coefficient of low-frequency band energy into zero, and reconstructing wavelet packet coefficients corresponding to other frequency bands to obtain an IMF without low-frequency illusive components; finally, performing Hilbert transformation on the IMF without the illusive components to obtain an HH (Hilbert-Huang) spectrogram, and identifying voltage sag sources according to catastrophe points, amplitudes, harmonic waves and frequencies of the HH spectrogram. Different characteristics of different voltage sag sources can be identified from the HH spectrogram only by taking the amplitudes, the catastrophe points and the harmonic waves as characteristics, the voltage sag sources are differentiated, so that times of non-identification and mistaken identification are effectively decreased, and identification efficiency is improved.

Description

technical field [0001] The invention relates to a voltage sag source identification method based on Hilbert-Huang transformation and wavelet packet energy spectrum, which belongs to the field of power system power quality analysis. Background technique [0002] Voltage sag refers to an event in which the root mean square value of the power frequency voltage at a certain point suddenly drops in a short period of time, and its typical duration is 0.5~30 cycles. The International Electrotechnical Commission (IEC) defines it as falling to 90%~ of the rated value 1%, which is defined by the Institute of Electrical and Electronics Engineers (IEEE) as falling to 90% to 10% of the rated value. The rapid development of economy and technology has made complex electronic equipment widely used in power consumption departments, and many equipment are sensitive to short-term voltage changes. For example: short-term voltage sags will cause tripping of speed control equipment (amplitude dr...

Claims

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Application Information

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IPC IPC(8): G01R19/00
Inventor 邹金慧祁博范玉刚吴建德黄国勇王晓东张光辉邵宗凯
Owner KUNMING UNIV OF SCI & TECH
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