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Cycle sampling method in quality of power supply in electrical network

A technology for power quality and power grids, applied in frequency measurement devices, spectrum analysis/Fourier analysis, etc., can solve problems such as large measurement errors and lost sampling points

Active Publication Date: 2006-02-01
STATE GRID CORP OF CHINA +3
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  • Application Information

AI Technical Summary

Problems solved by technology

However, because it automatically tracks and phase-locks the frequency of the first few cycles of the current cycle of the system, it cannot be completely equal to the frequency of the current cycle, and effective sampling points will still be lost during the sampling process, and the measurement error is still large

Method used

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  • Cycle sampling method in quality of power supply in electrical network
  • Cycle sampling method in quality of power supply in electrical network
  • Cycle sampling method in quality of power supply in electrical network

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 2

[0059] Follow the steps below in order:

[0060] 1. According to the frequency of 6.4KHz (f=2 n *50Hz, n=7) sampling frequency to collect secondary side voltage and current, collecting 128 points

[0061] 2. Carry out waveform fitting with the least square method, restore the collected 128 points to the waveform,

[0062] 3. Find the zero-crossing point of the waveform by the method of least squares, and determine a complete cycle,

[0063] 4. According to the sampling frequency of f=128*50Hz, the fitting waveform obtained above is re-sampled, and 128 points are collected.

[0064] 5. Analyze the power quality index values ​​in the power system according to the AC signal values ​​such as voltage and current at 128 points.

[0065] The principle of the hardware of embodiment 2 and the flow process of software are similar to embodiment 1, wherein, transmitter adopts 16 voltage-type and current-type transmitters, those skilled in the art need not pay Creative labor can be rea...

Embodiment 3

[0067] Follow the steps below in order:

[0068] 1. According to the frequency f=2 n *50Hz, n=8 sampling frequency to collect secondary side voltage and current, collect 256 points

[0069] 2. Fit and restore the collected 256 points to the waveform by linear interpolation

[0070] 3. Use the wavelet transform method to find out the zero-crossing point of the waveform to determine a complete cycle.

[0071] 4. According to f=2 n *50Hz, n=6 sampling frequency, re-sampling the fitted waveform obtained above, collecting 64 points,

[0072] 5. Analyze the value of each power quality index in the power system according to the AC signal values ​​such as voltage and current at 64 points.

[0073] The principle of the hardware and the flow of the software of the third embodiment are similar to those of the first embodiment.

Embodiment 4

[0075] Follow the steps below in order:

[0076] According to frequency f=2 n *50Hz, n=9 sampling frequency to collect secondary side voltage and current, collect n1 points

[0077] Fit the collected n1 points into a waveform by the least square method,

[0078] Use the least squares method to find the zero crossing point of the waveform to determine a complete cycle,

[0079] According to the sampling frequency of f=2n*50Hz, n=8, the fitting waveform obtained above is re-sampled, and n2 points are collected,

[0080] According to the AC signal values ​​such as voltage and current of n2 points, the value of each power quality index in the power system is analyzed.

[0081] The principle of the hardware and the flow of the software of the fourth embodiment are similar to those of the first embodiment.

[0082] The above-mentioned embodiments of the present invention have been adopted in practice, and good technical effects have been achieved. The accuracy of measuring each...

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Abstract

A method of cycle sampling for detecting electric energy quality includes using a fixed sampling frequency for sampling and using waveform fitting technique to restore it to be waveform, finding out zero ¿C crossover point of the waveform with least square method to obtain a complete cycle, carrying out secondary sampling on fitted waveform and analyzing electric energy quality index in system according to these points.

Description

(1) Technical field: [0001] The invention relates to a method for measuring power quality indicators in a power system, in particular to a cycle sampling method in power grid power quality. (two) background technology: [0002] With the development of economy, electricity plays an increasingly important role in economic life. The quality of electric energy is directly related to the overall benefit of the national economy. At present, the impact and non-linear loads in the power grid are increasing, which leads to serious deterioration of power quality problems such as harmonics, voltage fluctuations, and three-phase imbalances; and a large number of sensitive loads such as control equipment and electronic devices based on computer systems The emergence of temporary overvoltage and transient overvoltage, voltage sags and short-time interruptions, etc. The economic losses caused by power quality problems that have not been paid attention to by people are also increasing. The...

Claims

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Application Information

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IPC IPC(8): G01R23/02G01R23/16
Inventor 许杏桃丁伟李进卢春
Owner STATE GRID CORP OF CHINA
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