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High-robustness frequency estimation method for three-phase electric power system

A three-phase power and frequency estimation technology, applied in the direction of frequency measurement devices, etc., can solve the problems of slow frequency estimation, large error, and no consideration of negative sequence voltage components, etc., and achieve small changes in weight coefficients and changes in weight coefficients Large, Accurately Estimated Effects

Active Publication Date: 2019-09-17
SOUTHWEST JIAOTONG UNIV
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Problems solved by technology

However, when the three-phase power system is in an unbalanced state (such as a single-phase short-circuit fault), a negative-sequence voltage component appears. The above existing methods are based on the test and analysis of the positive-sequence voltage signal, without considering the negative-sequence voltage component. The speed of its frequency estimation is slow and the error is large

Method used

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  • High-robustness frequency estimation method for three-phase electric power system
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  • High-robustness frequency estimation method for three-phase electric power system

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Embodiment

[0042] A specific embodiment of the present invention is a method for frequency estimation of a robust three-phase power system, the steps of which are as follows:

[0043] A. Signal collection

[0044] Collect the voltage signal of the three-phase power system, and obtain the complex voltage signal v(k) at the current moment k through Clarke transformation;

[0045] B. Estimation of complex voltage signal

[0046] The estimated value of the complex voltage signal at the next moment k+1 is output by an adaptive filter based on a wide linear model

[0047]

[0048] Among them, h(k) represents the standard weight coefficient of the filter at the current moment k, and its initial value is 0.99+j0.15, where j is an imaginary number unit; g(k) represents the conjugate weight coefficient of the filter at the current moment k, where The initial value is 0; v * (k) is the conjugate value of the complex voltage signal v(k) of the current moment k;

[0049] C. Error calculation...

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Abstract

The invention discloses a robust frequency estimation method for an unbalanced three-phase electric power system. The method mainly comprises the following steps: A, performing collecting and converting to obtain a complex voltage signal v(k); B, obtaining a complex voltage signal estimation value at the next moment; C, calculating an error D of the complex voltage signal; D, updating weight coefficients: calculating an error order adjustment factor lambda (k) = beta lambda (k-1) + gamma e2 (k-1), the standard weight coefficient at the next moment and the conjugate weight coefficient at the next moment; and E, estimating a frequency value at the current moment. According to the method, the estimation speed is high, and the error is small; when the three-phase electric power system is in an unbalanced state, the frequency of the system can still be quickly and accurately estimated; and the method is high in robustness.

Description

technical field [0001] The invention relates to a frequency estimation method of a power system, in particular to a frequency estimation method of a three-phase power system. Background technique [0002] Frequency is one of the important indicators of power quality and an important parameter reflecting the operating state of the power system; it will slowly change in a small range with load fluctuations. In a stable operating state, the output power of the generator is balanced with the system load and loss, and the frequency of the power system is the nominal value. Changes in frequency values ​​can indicate anomalies and disturbances such as harmonics, noise, and unbalanced voltages, so fast and accurate estimates of frequency in power systems are required. [0003] In a three-phase power system, the traditional frequency estimation method based on single-phase voltage has certain limitations, especially when there is a sudden change in a certain phase. Therefore, in th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R23/02
CPCG01R23/02
Inventor 赵海全汪倬男
Owner SOUTHWEST JIAOTONG UNIV
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