Power quality disturbance identification method based on improved HHT algorithm

A technology of power quality disturbance and identification method, applied in the direction of measuring electrical variables, measuring electricity, measuring devices, etc., can solve problems such as non-stationary signals that cannot be identified

Active Publication Date: 2018-12-07
XIAN UNIV OF TECH
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Problems solved by technology

[0005] The purpose of the present invention is to provide a power quality disturbance identification method based

Method used

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  • Power quality disturbance identification method based on improved HHT algorithm
  • Power quality disturbance identification method based on improved HHT algorithm
  • Power quality disturbance identification method based on improved HHT algorithm

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specific Embodiment approach

[0117] The method of the present invention is simulated based on Matlab, at first given signal is as shown in formula 5:

[0118]

[0119] The unit of time t is s (second), the voltage interruption occurs from 0.4s to 0.5s, the voltage fluctuation occurs from 1s to 1.5s, the third harmonic is contained in 2s to 2.5s, and the fifth harmonic is contained in 2.5s to 3 .

[0120] The sampling frequency is 30kHz, the SAX algorithm aggregates every 10 data points, takes 10 characters respectively (abcdefghij), rearranges them in a row at 0.02s per cycle to obtain a symbol matrix, then each cycle has 30000÷10÷150=20 characters, only the left and right symbol matrices where the signal changes are shown here; Figure 5 As shown, from left to right, 0.36s to 0.54s correspond to voltage interruptions, 0.96s to 1.14s correspond to voltage fluctuations, 1.92s to 2.10s correspond to the third harmonic, and 2.42s to 2.60s correspond to the fifth harmonic (wherein changes in the frequenc...

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Abstract

The invention discloses a power quality disturbance identification method based on an improved HHT algorithm, which comprises the steps of firstly, collecting signals, and segmenting the signals by using an SAX algorithm; secondly, performing HHT analysis on the different segments of segmented signals, and extracting feature values of the different segments of signals; then identifying the power quality disturbance condition by using a decision-making tree according to the extracted feature values; and finally performing iterative HHT analysis on identified normal power signals so as to further judge whether there is minor disturbance or not, and thus achieving complete identification for the power quality disturbance. The power quality disturbance identification method disclosed by the invention based on the improved HHT algorithm solves a problem that it is impossible to identity non-stationary signals the prior art. The signals are segmented by adopting the SAX algorithm, and then different segments of signals are analyzed to further judge whether there is disturbance or not, thereby well solving a problem of mode aliasing occurred with high frequency and small amplitude.

Description

technical field [0001] The invention belongs to the technical field of power quality analysis and monitoring, and relates to a power quality disturbance identification method based on an improved HHT algorithm. Background technique [0002] With the continuous innovation of science and technology and the rapid development of the economy, the connection of long-distance DC power transmission and large-scale power grids has caused great changes in the structure of the power grid; With the rapid development, new energy power generation technology has the characteristics of randomness, volatility, intermittent and non-schedulability; with the wide application and in-depth research of micro-grid technology, the types and quantities of micro-power sources are becoming more and more, micro-grid There will be many power quality problems in the power supply, all of which are caused by the special properties of the micro power supply itself. A large number of non-linear loads and imp...

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Application Information

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IPC IPC(8): G01R31/00
CPCG01R31/00
Inventor 李宁何复兴王倩高亮
Owner XIAN UNIV OF TECH
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