A Fast Frequency Estimation Method for Three-Phase 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, no consideration of negative sequence voltage components, large errors, etc.

Active Publication Date: 2020-07-07
SOUTHWEST JIAOTONG UNIV
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  • Abstract
  • Description
  • Claims
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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 Fast Frequency Estimation Method for Three-Phase Power System
  • A Fast Frequency Estimation Method for Three-Phase Power System
  • A Fast Frequency Estimation Method for Three-Phase Power System

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Embodiment

[0042] A kind of embodiment of the present invention is, a kind of frequency estimation method of fast three-phase power system, its steps 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(n) at the current moment n through Clarke transformation;

[0045] B. Estimation of complex voltage signal

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

[0047]

[0048] Among them, h(n) represents the standard weight coefficient of the filter at the current moment n, and its initial value is 0.99+0.15i, where i is an imaginary number unit; g(n) represents the conjugate weight coefficient of the filter at the current moment n, and its initial value value is 0; v * (n) is the conjugate value of the complex voltage signal v (n) of current moment n;

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

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Abstract

A fast frequency estimation algorithm for a three-phase power system, the main steps are: A. Collect and transform to obtain a complex voltage signal v(n); B. Obtain the estimated value of the complex voltage signal at the next moment, C. Calculate the complex voltage signal The error D of , calculate the expected value of square error p(n)=βp(n‑1)+e 2 (n), and then calculate the step size at the current moment μ(n)=αμ(n‑1)+γe 2 (n), and then calculate the standard weight coefficient h(n+1)=h(n)+μ(n)[3p(n)‑e at the next moment 2 (n)]e(n)v * (n) and conjugate weight coefficient g(n+1)=g(n)+μ(n)[3p(n)‑e 2 (n)]e(n)v(n); E. Estimating the frequency value at the current moment has a fast estimation speed and small error. When the system is in an unbalanced state, it can still estimate the system frequency quickly and accurately.

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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