Harmonic detection method combining extreme symmetry mode decomposition and Hilbert transform

A pole-symmetry mode and harmonic detection technology, which is applied in measuring devices, spectrum analysis, measuring electrical variables, etc., can solve problems such as strong noise dependence, achieve good real-time performance, high detection accuracy, and strong self-adaptive decomposition ability Effect

Active Publication Date: 2018-11-06
SHANGHAI UNIVERSITY OF ELECTRIC POWER
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Problems solved by technology

[0004] The present invention aims at the problems existing in common harmonic detection methods, and proposes a harmonic detection method combining pole symmetric mode decomposition and Hilbert transform, which overcomes the overfitting and underfitting of the envelope of the EMD method It can also effectively avoid the modal aliasing phenomenon in the harmonic detection of the EMD method without adding noise, and avoid the disadvantage that the detection results of the EEMD method are highly dependent on the selected noise

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  • Harmonic detection method combining extreme symmetry mode decomposition and Hilbert transform
  • Harmonic detection method combining extreme symmetry mode decomposition and Hilbert transform
  • Harmonic detection method combining extreme symmetry mode decomposition and Hilbert transform

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Embodiment Construction

[0028] like figure 1 The flow chart of the harmonic detection method combining pole-symmetric mode decomposition and Hilbert transform is shown, including the following steps:

[0029] 1. Denoise and discretize the acquired voltage or current signal, remove the high-frequency noise of the signal, and obtain a preprocessed signal.

[0030] 2. Use the pole-symmetric modal decomposition ESMD method to modal decomposition of the acquired signal, and obtain each intrinsic modal function.

[0031] like figure 2 The flow chart of the signal decomposition method of the pole-symmetric modal decomposition method is shown, and this step specifically includes the following sub-steps:

[0032] 2.1. Define the preprocessed voltage or current signal as where N is a positive integer. Find all local extreme points E in X i (i=1, 2, ..., n), n is the number of local extreme points.

[0033] 2.2. Connect adjacent extreme points with line segments in turn, and find the midpoint F of the l...

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Abstract

The invention relates to a harmonic detection method combining extreme symmetry mode decomposition and Hilbert transform, which is aimed at the problem that the existing power system harmonic signal detection methods are not high in precision, and the problem that well-studied empirical mode decomposition has modal aliasing in harmonic detection, can provide a specific harmonic detection step based on a combination of the extreme symmetry mode decomposition ESMD and Hilbert transform (HT) according to the extreme symmetry mode decomposition theory and algorithm. Firstly, a signal is subjectedto extreme symmetry mode decomposition to obtain a series of intrinsic mode functions of different feature scales. Then, Hilbert transform is performed on the IMF component to obtain the instantaneousamplitude and instantaneous frequency information of each harmonic. The invention has strong self-adaptive decomposition ability in harmonic detection, high detection precision and good real-time performance, and can effectively avoid the modal aliasing phenomenon of the EMD method in harmonic detection without adding noise.

Description

technical field [0001] The invention relates to a harmonic detection technology, in particular to a harmonic detection method combining pole-symmetric mode decomposition and Hilbert transform. Background technique [0002] In recent years, with the continuous increase of the penetration rate of distributed power in the power grid, the power quality problems caused by the access of a large number of distributed power to the power grid have become increasingly prominent; in addition, more and more power electronic rectifiers, frequency converters and other nonlinear loads are used. , making the harmonic pollution more and more serious and the power quality worse. Because the power grid harmonics are affected by factors such as randomness, distribution and sub-stationarity, it is difficult to achieve real-time accurate measurement of harmonics. Real-time and accurate harmonic detection is a reliable guarantee for further harmonic control. Therefore, how to quickly and effecti...

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Application Information

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IPC IPC(8): G01R23/163
CPCG01R23/163
Inventor 张宇华赵晓柯王育飞薛花
Owner SHANGHAI UNIVERSITY OF ELECTRIC POWER
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