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Reactive power measuring method based on digital filtering

A technology of power measurement and digital filtering, which is applied in the direction of electric power measurement by applying digital technology, can solve the problems of inability to reflect the sum of the reactive power of various harmonics, unreasonable measurement of reactive power, etc. Design simple effects

Inactive Publication Date: 2004-07-28
TSINGHUA UNIV
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  • Application Information

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Problems solved by technology

From this point of view, in a power grid with harmonics, it is unreasonable to use traditional methods to measure reactive power, and the results cannot reflect the sum of the reactive power of each harmonic in the frequency band of interest

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  • Reactive power measuring method based on digital filtering
  • Reactive power measuring method based on digital filtering
  • Reactive power measuring method based on digital filtering

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Embodiment Construction

[0045] The principle block diagram of the reactive power measurement method based on the digital phase-shift filter of the present invention is shown in FIG. 2 . With reference to Fig. 2, the working process of the reactive power measuring method based on digital phase-shift filtering of the present invention is as follows:

[0046] 1. Firstly, a pair of analog voltage signal u(t) and analog current signal i(t) measured from the 50Hz power frequency power grid are respectively set according to the same fixed sampling frequency F S Perform A / D conversion to obtain discrete digital voltage signal u(n) and digital current signal i(n). The highest order M of concerned harmonics is 18 times, the corresponding frequency of the highest order harmonic is 900Hz, and the selected sampling frequency F S =8000Hz, which is greater than twice the highest harmonic frequency.

[0047] 2. After the digital voltage signal u(n) obtained in the first step above is processed by the first group o...

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Abstract

The present invention relates to a method for measuring reactive power based on digital filtration, which is characterized by that firstly, the analogue voltage signal and analogue current signal measured from electric network for measuring reactive power are undergone the process of A / D conversion to obtain discrete digital voltage signal and digital current signal. Said digital voltage signal is passed through the digital phase shift filter to obtain signal u'(n), and the digital current signal i(n) is passed through the digital phase shift filter to obtain signal i'(n), said signals of u'(n) and i'(n) are multiplied to obtain signal q(n), q(n)=u'(n)X i'(n), the signal q (n) is undergone the process of D.C. filtration so as to obtain its D.C. component Q(n), i.e. reactive powder.

Description

technical field [0001] The invention relates to a reactive power measurement method based on digital filtering. According to a pair of power frequency voltage and current input signals containing harmonics, the method obtains the sum of the fundamental reactive power and the reactive power of each harmonic Total reactive power data. The invention belongs to the technical field of electric parameter measurement. Background technique [0002] In the power system, reactive power and reactive energy are very important power parameters. The size of reactive power has a great influence on the transmission efficiency and power quality of the power system. By accurately calculating the reactive power of the system, it can Take corresponding measures to distribute and dispatch the reactive power of the power grid, or compensate the reactive load, and suppress the transmission line loss and voltage decline caused by reactive power, so as to achieve the effect of improving power quali...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R21/133
Inventor 庞浩俎云霄李东霞王赞基
Owner TSINGHUA UNIV