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DFT (discrete Fourier transform) based synchronous phaser phase angle measurement method

A phase angle measurement and synchronized phasor technology, which is applied to the phase angle between voltage and current, measuring devices, and measuring electrical variables, etc., can solve the problems of increasing phase angle errors, etc., and achieve fast speed, simple principle, and calculation The effect of fewer steps

Active Publication Date: 2015-07-22
FUZHOU UNIVERSITY
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Problems solved by technology

[0005] The purpose of the present invention is to provide a DFT-based synchronized phasor phase angle measurement method to solve the problem of increased phase angle error of the DFT algorithm in the case of frequency offset

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  • DFT (discrete Fourier transform) based synchronous phaser phase angle measurement method
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  • DFT (discrete Fourier transform) based synchronous phaser phase angle measurement method

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Embodiment Construction

[0034] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0035] When the power grid frequency shifts, the traditional DFT algorithm will increase the phase angle error due to asynchronous sampling when calculating the synchronized phasor phase angle. The phase angle error is divided into two parts: fixed error and dynamic error. The DFT value of each data window is rotated and mathematically calculated to reduce the dynamic error of the phase angle as much as possible, and then the calculated phase angle is compensated by a fixed error to obtain a high-precision phase angle value. A DFT-based synchronized phasor phase is proposed. Angle measurement method.

[0036] figure 1 is the total error diagram of the phase angle of the traditional DFT under the non-synchronous sampling condition of the embodiment of the present invention. In this embodiment, the number of sampling points in one period of the power si...

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Abstract

The invention relates to a DFT (discrete Fourier transform) based synchronous phaser phase angle measurement method. The method includes: 1), calculating out the frequency deviation rate delta lambda by the aid of a frequency tracing technology to trace instantaneous frequency f of electric signals according to the rated frequency fo of the electric signals and the instantaneous frequency f, and calculating out a fixed error value of the synchronous phasor phase angle according to the frequency deviation rate delta lambda and sampling points N of one same period of the electric signals; 2), respectively subjecting the front N / 8 points and rear N / 8 points of the to-be-measured phase angle to DFT to acquire phasors X2 and X3, multiplying the phasor X2 by corresponding rotating factors and coefficients, multiplying the phase X3 by corresponding rotating factors and coefficients, adding the two to acquire a new phasor X and calculating phase angles Qm of the new phasors; 3), performing fixed error compensation on the acquired phase angles Qm of the new phasors in the step 2) to acquire accurate phase angle measurement values. With the method, synchronous phasor phase angle measurement value precision with the DET algorithm under the asynchronous utilization condition can be effectively improved, and a good inhabiting effect on harmonic waves is achieved.

Description

technical field [0001] The invention relates to a method for measuring the phase angle of a synchronized phasor based on DFT. Background technique [0002] The main features of the modern power system are large units, large power plants, large power grids, ultra-high voltage long-distance AC-DC hybrid transmission, which indicates that the development level of the power system has entered a new stage, and the future power system will be It exhibits some new characteristics that are not available in smaller-scale power systems. At the same time, a large number of new control technologies have been adopted in the operation of the power grid, such as generator excitation and speed regulation systems, dynamic reactive power compensation devices, etc., making the dynamic characteristics of the power system increasingly complex. At the same time, with the progress of the power market and environmental protection requirements, various facilities in the power grid have to operate c...

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Application Information

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IPC IPC(8): G01R25/00
Inventor 金涛唐晓艳
Owner FUZHOU UNIVERSITY
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