Harmonious wave detecting method in power system

A power system and harmonic detection technology, applied in spectrum analysis/Fourier analysis, etc., can solve problems such as low accuracy and poor robustness, and achieve the effect of improving resolution

Inactive Publication Date: 2017-05-31
HUAZHONG UNIV OF SCI & TECH
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Problems solved by technology

[0004] Although the wavelet packet transform solves the time domain, frequency domain analysis and resolution problems in the high frequency band, the wavelet filter used in the wavelet packet transform almost always has aliasing phenomenon in the

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  • Harmonious wave detecting method in power system
  • Harmonious wave detecting method in power system
  • Harmonious wave detecting method in power system

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Embodiment Construction

[0023] In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.

[0024] The flow of the power system harmonic detection method provided by the embodiment is as follows: figure 1 shown, including the following steps:

[0025] S01. Obtain the input sequence x[n] by sampling the signal source;

[0026] S02, utilize the five-layer db40 wavelet packet algorithm to carry out wavelet packet decomposition to the input sequence x[n], and determine the fundamental fr...

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Abstract

The invention discloses a harmonious wave detecting method in a power system. On the basis of five-layered db 40 wavelet packet transformation, hilbert transform is applied to perform frequency shift operation; every harmonic component is transferred to a side frequency band with relatively high precision, so as to perform wavelet packet decomposition and signal reconstruction, thus the high-precision detection of every harmonic wave is realized. The method includes steps of S01, moving every frequency classification of a former signal to 25-75 Hz frequency sections by hilbert transform; S02, respectively performing wavelet packet decomposition and reconstruction on every component after moving frequency; S03, respectively moving frequency of every restructured component and restoring to original frequency section; S04, acquiring the harmonious wave detecting result according to the recorded waveform data. The method provided by the invention eliminates the adverse influence of wavelet filter aliasing of the middle frequency section on the detecting precision, and has high-resolution time frequency analysis ability, and can effectively position the transient state disturbance; the detecting precision is high and the instantaneity is good; the method is applicable to various occasions of harmonious wave detection.

Description

technical field [0001] The invention belongs to the field of power system signal processing, and more specifically relates to a method for detecting harmonics in a power system. Background technique [0002] As the power grid system becomes more and more complex, the increasingly open distributed power grid-connected strategy and the use of diverse non-linear devices have brought a series of problems to the stability of the power grid. Harmonics are one of the typical power quality problems. The existence of harmonics may not only cause the devices connected to the power grid to fail to work normally, but also seriously affect the quality of electric energy, causing huge economic losses to power companies and society. The accurate detection of harmonics can not only reduce the error of electric energy measurement, but also provide accurate reference data for harmonic control, so as to study targeted control programs to deal with the problem of harmonic pollution in power sy...

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Application Information

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IPC IPC(8): G01R23/16
CPCG01R23/16
Inventor 肖厦颖李开成王凌云
Owner HUAZHONG UNIV OF SCI & TECH
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