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Transient power quality disturbance detection method based on WMM and HATF

A technology of transient power quality and detection methods, applied in the direction of measuring electric variables, measuring electricity, measuring devices, etc., can solve the randomness uncertainty of transient disturbance signals, affect power system power quality, transient power quality problems, etc. problem, achieve good detection effect, good real-time performance, and simple algorithm

Pending Publication Date: 2020-12-25
CHINA THREE GORGES UNIV
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Problems solved by technology

[0002] In the existing technology, renewable energy and electric vehicles are connected to the grid through nonlinear power electronic devices, which seriously affects the power quality of the power system, and the problem of transient power quality is particularly serious.
The premise of controlling and improving the transient power quality is to effectively detect the transient disturbance signal, but the transient disturbance signal is random and uncertain, and due to factors such as sampling error and external interference in the channel transmission process, the acquired waiting The measured signal is often polluted by noise
[0003] The sensitivity of the traditional transient power quality disturbance detection method is greatly affected in the strong noise environment, how to effectively reduce the noise is a problem that must be solved when the disturbance signal is detected
Donoho et al. first proposed the use of wavelet hard threshold and soft threshold functions for noise reduction, but due to great limitations in practical applications, many studies have focused on the improvement of threshold functions and their applications

Method used

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  • Transient power quality disturbance detection method based on WMM and HATF
  • Transient power quality disturbance detection method based on WMM and HATF
  • Transient power quality disturbance detection method based on WMM and HATF

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Embodiment Construction

[0067] The transient power quality disturbance detection method based on WMM and HATF includes the following steps:

[0068] Step 1: Sampling 100 points per period of the disturbance signal, that is, setting the sampling frequency to 5kHz, to obtain the sampling sequence s(t);

[0069] Step 2: Start denoising the sampling sequence s(t), and select a suitable wavelet base. Because of its good similarity and symmetry, the Sym4 wavelet is chosen as the wavelet basis function.

[0070] Then Sym4 can be used as a basic wavelet function. Scaling and translating it yields a wavelet sequence:

[0071]

[0072] In the formula, Sym(t) is the basic wavelet function, Sym α,β (t) is the stretched and translated wavelet function, and α and β are scale factor and stretch factor respectively. For any signal Sym(t)∈L in the time domain 2 (R), the wavelet transform can be expressed as:

[0073]

[0074] Step 3: By obtaining the minimum frequency f of the sampling sequence s(t) min ...

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Abstract

The invention discloses a transient power quality disturbance detection method based on WMM and HATF. The method comprises the following steps: sampling disturbance signals to obtain a sampling sequence; selecting a proper wavelet basis; determining the maximum decomposition layer number N by acquiring the minimum frequency of the signal; and establishing a mathematical model of an adjustable factor mu according to the energy distribution characteristics of each decomposition layer of wavelet transform, and calculating an adjustment factor of each decomposition layer according to the model; calculating the threshold lambda of each decomposition layer; obtaining an adaptive threshold function of each decomposition layer, and processing detail coefficients after wavelet decomposition; performing wavelet reconstruction on the approximation coefficient and the detail coefficient of each decomposition layer; starting electric energy quality disturbance detection, locating a mutation point,solving the modulus maximum value and the position of the modulus maximum value, and the modulus maximum value point is the mutation point of the signal; and recording the time and time interval corresponding to the modulus maximum value point, i.e., the starting and ending time and duration of the disturbance. According to the method, the information of the abrupt change position is better reserved while noise reduction is carried out on the disturbance signal, and the accuracy of transient disturbance detection under noise interference is improved.

Description

technical field [0001] The invention relates to the field of transient power quality, in particular to a detection method for transient power quality disturbance based on WMM and HATF. Background technique [0002] In the prior art, renewable energy and electric vehicles are connected to the grid through nonlinear power electronic devices, which seriously affects the power quality of the power system, and the problem of transient power quality is particularly serious. The premise of controlling and improving the transient power quality is to effectively detect the transient disturbance signal, but the transient disturbance signal is random and uncertain, and due to factors such as sampling error and external interference in the channel transmission process, the acquired waiting The measured signal is often polluted by noise. [0003] The sensitivity of the traditional transient power quality disturbance detection method is greatly affected in the strong noise environment, h...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06K9/00G01R31/00
CPCG01R31/00G06F2218/06
Inventor 程杉严潇徐敬伟王睿
Owner CHINA THREE GORGES UNIV
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