Inter-harmonics measuring method for power grid

A measurement method and harmonic technology, which are applied in the field of online detection of power quality, can solve the problems of large amount of calculation, poor anti-interference, and difficulty in meeting the real-time requirements of online detection of power quality, etc., and achieve the effect of short sampling period and easy implementation.

Active Publication Date: 2013-08-07
STATE GRID CORP OF CHINA +1
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Problems solved by technology

However, due to the inherent non-stationarity of inter-harmonics, the frequency is difficult to predict, and the amplitude is often much smaller than the fundamental wave and harmonic components, the improved FFT method and the AR model power spectrum based on second-order statistics are currently used. It is difficu

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  • Inter-harmonics measuring method for power grid

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[0026] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0027] figure 2 The block diagram of the hardware structure, as shown in the figure, is an inter-harmonic online measurement device, including a voltage measurement module for collecting three-phase voltage analog quantities, a current measurement module for collecting three-phase current analog quantities, and an A / D conversion module , DSP data processing module, ARM9 data management and communication module, dual-port RAM transmission module and data storage module, the output of the voltage measurement module and the current measurement module is connected to the A / D conversion module, and the output of the A / D conversion module Connect described dual-port RAM transmission module; Dual-port RAM transmission module is connected with described DSP data processing module; Dual-port RAM transmission module is connected with described ARM9 ...

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Abstract

The invention discloses an inter-harmonics measuring method for the power grid. The inter-harmonics measuring method includes: 1) sampling three-phase current and three-phase voltage of the power grid by sampling frequency fs and sampling points N in real time, and transmitting sampled signals to a DSP (digital signal processor) processing module; and 2) detecting inter-harmonics by means of FFT (fast fourier transform algorithm) according to the current and voltage signals sampled in the step 1). The step 2) includes: 21) utilizing the sampled signals obtained in the step 1) as original signals; 22) calculating amplitude, phase and frequency of fundamental harmonics and harmonics; 23) calculating frequency domain signals of the fundamental harmonics and harmonics; 24) subtracting frequency signals of the fundamental harmonics and harmonics obtained in the step 23) from the original signals to obtain windowed frequency domain signals of the inter-harmonics; and 25) calculating amplitude, phase and frequency of the inter-harmonics obtained in the step 24). On the basis of results obtained by conventional integral subharmonics measuring method, a Hanning window is selected as window function, and inter-harmonics measuring instantaneity is improved by filtering components of fundamental harmonics and integral subharmonics by frequency domain.

Description

technical field [0001] The invention relates to an online detection of electric energy quality, in particular to a method for measuring harmonics among power grids. Background technique [0002] Non-integral harmonics of the fundamental frequency, ie interharmonics, may also be generated by non-linear loads in the power system in addition to the integral harmonics of the fundamental frequency. According to IEC-61000-2-1, interharmonic (Interharmonic) is defined as: between the harmonic components of voltage and current signals, there is a signal whose frequency is not an integer multiple of the fundamental frequency, which is manifested as a discrete spectrum or broadband spectrum. The main interharmonic sources in the power system include: frequency conversion speed control device; high voltage direct current transmission; motor and electric arc furnace, etc. Similar to harmonics, inter-harmonics will not only affect the operation of passive filters and cause flicker prob...

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Application Information

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IPC IPC(8): G01R23/16
Inventor 池源唐文左崔荣李自若刘国平梁文举王玲杨洪钦
Owner STATE GRID CORP OF CHINA
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