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Wavelet threshold denoising method for low-frequency oscillation Prony analysis

A wavelet threshold denoising and low-frequency oscillation technology, applied in the field of denoising, can solve problems such as poor self-adaptive ability and reconstructed signal distortion, and achieve the effects of improving accuracy, reducing fixed deviation, and enhancing stability and security

Active Publication Date: 2020-01-17
ELECTRIC POWER RES INST OF GUANGXI POWER GRID CO LTD
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Problems solved by technology

[0004] At present, the commonly used denoising algorithms suitable for Prony analysis include smoothing filter algorithm, fuzzy filter method, wavelet threshold denoising method, etc. Among them, the wavelet threshold denoising method is applied because of its high sensitivity, strong anti-interference ability and good denoising effect. Wide range, but the commonly used wavelet threshold denoising also has problems such as poor adaptive ability and possible distortion of the reconstructed signal

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  • Wavelet threshold denoising method for low-frequency oscillation Prony analysis

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Embodiment Construction

[0038] In order to better understand the present invention, the present invention will be further described below in conjunction with specific embodiment:

[0039] A wavelet threshold denoising method for Prony analysis of low-frequency oscillations, comprising the following steps:

[0040] Step 1, process the noise-containing signal to obtain N-level wavelet expansion coefficients d of different scales j,k , d j-1,k ,...,d j-N+1,k ; The mathematical model of the noise-containing signal is y(t)=x(t)+ε(t), x(t) is the real signal, ε(t) is the noise signal, and y(t) is sampled at equal intervals to obtain The sample point sequence corresponding to the signal is c j+1,k , for c j+1,k Perform N-level discrete wavelet transform to obtain N-level wavelet expansion coefficients d of different scales j,k , d j-1,k ,...,d j-N+1,k . Where j is the scale order, the larger j is, the smaller the scale is, and k is the position coefficient.

[0041] Step 2, based on the wavelet exp...

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Abstract

The invention relates to a denoising method in low-frequency oscillation analysis of power systems, in particular to a wavelet threshold denoising method for low-frequency oscillation Prony analysis.The invention improves the traditional wavelet threshold denoising algorithm by introducing new threshold selection and threshold function. The selection of new threshold can ensure that the wavelet coefficient varies with the distribution of scales, and fit the actual distribution of noise in different types of signals at each layer, so as to ensure sufficient denoising ability without distortionof reconstructed signals. Compared with the common soft threshold function, the new threshold function reduces the fixed deviation, and the continuity of the function is ensured compared with the common hard threshold function, thus eliminating the possible oscillation of the reconstructed signal.

Description

technical field [0001] The invention discloses a denoising method in low-frequency oscillation analysis of a power system, in particular to a wavelet threshold denoising method for low-frequency oscillation Prony analysis. Background technique [0002] The low-frequency oscillation of the power system refers to the phenomenon that after the system is disturbed, the rotors of synchronous generators running in parallel in the system swing relative to each other, resulting in power, voltage and other electric power oscillations in the system. Once the low-frequency oscillation occurs, it will last for a long time before disappearing, which seriously threatens the safe and stable operation of the power grid and may cause large-scale power outages. The purpose of studying low-frequency oscillations in power systems is to analyze whether there are weakly damped oscillation modes in the system, and when there are weakly damped oscillation modes in the system, take measures to enhan...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/34G06K9/00
CPCG01R31/346G01R31/343G06F2218/04
Inventor 刘默斯孙志媛李明珀梁水莹丘晓茵
Owner ELECTRIC POWER RES INST OF GUANGXI POWER GRID CO LTD
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