A Robust Frequency Estimation Method for Three-Phase Power Systems

A technology for three-phase power and frequency estimation, which is applied in the field of frequency estimation of three-phase power systems with strong robustness, and can solve the problems of not considering negative sequence voltage components, slow frequency estimation, and large errors.

Active Publication Date: 2020-07-07
SOUTHWEST JIAOTONG UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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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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  • A Robust Frequency Estimation Method for Three-Phase Power Systems
  • A Robust Frequency Estimation Method for Three-Phase Power Systems
  • A Robust Frequency Estimation Method for Three-Phase Power Systems

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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 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) at the current moment k;

[0049] C. Error calculation of comple...

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Abstract

A robust frequency estimation method for an unbalanced three-phase power system, the main steps of which are: A. acquisition and transformation to obtain a complex voltage signal v(k); B. obtaining the estimated value of the complex voltage signal at the next moment; C. calculating The error D of the complex voltage signal and the update of the weight coefficient: calculate the error order adjustment factor λ(k)=βλ(k‑1)+γe 2 (k‑1); the standard weight coefficient at the next moment, the conjugate weight coefficient E at the next moment, and the frequency value at the current moment are estimated. The estimation speed is fast and the error is small. When the three-phase power system is in an unbalanced state, it is still It can quickly and accurately estimate the frequency of the system, and has strong 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 Patents(China)
IPC IPC(8): G01R23/02
CPCG01R23/02
Inventor 赵海全汪倬男
Owner SOUTHWEST JIAOTONG UNIV
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