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A method and system for obtaining instantaneous frequency of electrical signals

An instantaneous frequency and signal technology, applied in the field of electric power, to achieve the effect of accelerating the convergence speed, reducing the influence, and accurate initial iteration frequency

Active Publication Date: 2019-05-14
HAINAN UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In a relatively stable state, with the help of the least squares method, SDFT can continuously estimate the instantaneous frequency, suppress harmonics and smooth noise, but for non-stationary states, the simple SDFT algorithm is powerless

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  • A method and system for obtaining instantaneous frequency of electrical signals
  • A method and system for obtaining instantaneous frequency of electrical signals
  • A method and system for obtaining instantaneous frequency of electrical signals

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Embodiment Construction

[0036] In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0037] In one embodiment, a method for obtaining the instantaneous frequency of an electrical signal such as figure 1 shown, including the following steps:

[0038] S1. The sampling frequency is set in advance, and the electrical signal is sampled according to the sampling frequency;

[0039] S2. Obtain frequency calibration values ​​under different window lengths, the frequency calibration value f i =f / L i , L i For different data lengths, f is the sampling signal frequency, f i It is the frequency calibration value under different data lengths;

[0040] S3. According to the short-time Fourier transform algorithm (SDRT), the frequency calculation values ​​under different window lengths at the sampling time are obtained;

[0041] S4. Calculate the difference...

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Abstract

The invention relates to a method and a system for acquiring the instantaneous frequency of an electrical signal. The initial iterative frequency is determined by flexibly using a short-time Fourier transform method, and is applied to an iterative algorithm for acquiring the instantaneous frequency. The method and the system can provide more accurate initial iterative frequency, accelerate the convergence rate of the iteration process, and reduce the influence of window length and sampling frequency on the iteration result. The method is sensitive to the step change of signals, but insensitive to the following three interference factors: voltage or current signals modulated by other signals, direct-current bias including attenuation and noise. Hence, the method is very suitable for tracking the instantaneous frequency of instable power systems.

Description

technical field [0001] The present invention relates to the field of electric power, in particular to a method and system for acquiring the instantaneous frequency of electrical signals. Background technique [0002] In the power system, the frequency value of the voltage and current signals is the most important state parameter and operation index, and it is also a sign of the islanding phenomenon in the power system. The frequency value is a crucial parameter for the safe and stable operation of the power system. It can reflect the power quality and safety of the entire system. Too high or too low a frequency will bring harm to the power system. For example, reducing the frequency by 0.1Hz means 800MW of electricity is missing. In the past few decades, researchers have done a lot of research work on frequency measurement in the field of power engineering. These research works have gained a lot in the time domain, but in the transform domain, the main ones that can be used...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R23/02G01R23/16
CPCG01R23/02G01R23/16
Inventor 李晖陈敏杨永钦
Owner HAINAN UNIV