Harmonic Detection Method Combining Pole Symmetrical Mode Decomposition and Hilbert Transform

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 transformation. Background technique [0002] In recent years, with the increasing penetration rate of distributed power in the power grid, the power quality problems caused by the connection of a large number of distributed power to the power grid have become increasingly prominent; in addition, more and more nonlinear loads such as power electronic rectifiers and frequency converters are used , making the harmonic pollution more and more serious, and the power quality worsening. Because grid harmonics are affected by factors such as randomness, distribution, and substationarity, it is difficult to achieve real-time and accurate measurement of harmonics. Real-time and accurate harmonic detection is a reliable guarantee for further harmonic control. Therefore, how to quickly and effectively det...

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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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