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Harmonic energy metering method

A measurement method and harmonic current technology, applied in the direction of measuring electrical variables, measuring devices, instruments, etc., can solve problems such as spectrum leakage, increased design costs, inaccurate measurement of fundamental and harmonics, etc., to overcome spectrum leakage and reduce Computational Overhead Effects

Active Publication Date: 2009-07-22
HANGZHOU VANGO TECH
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Problems solved by technology

However, when the power grid frequency is inaccurate and other reasons cause asynchronous sampling, the problem of spectrum leakage in FFT will cause the fundamental component to leak into the harmonic, resulting in inaccurate measurement of the fundamental and harmonic
The improved method is to add window and interpolation to FFT to solve the problem of spectral leakage, but these two methods will greatly increase the complexity of calculation and storage capacity
In addition, the frequency spectrum leakage problem caused by grid frequency drift cannot be directly corrected by the above method, and must be solved by changing the sampling frequency with the help of phase-locked loop (hereinafter referred to as PLL) technology, but because the design of PLL requires a large number of analog circuits, it will make the design significantly increased cost

Method used

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Embodiment Construction

[0022] The invention provides a method for measuring harmonic electric energy, the principle block diagram of which is shown in figure 1 shown, including:

[0023] (1) From the voltage and current signals from the power grid, the fundamental wave is separated by low-pass filtering, and the harmonic signal is separated by high-pass filtering, and the fundamental current and fundamental voltage as well as the total harmonic current and total harmonic voltage are obtained ; In the process of fundamental wave current and fundamental wave voltage extraction, the low-pass filtering method adopted has flat gain characteristics in the area around the signal frequency of 50 Hz, when the frequency of the fundamental wave current and fundamental wave voltage fluctuates around 50 Hz , the low-pass filter will not bring gain errors.

[0024] (2) Use the infinitely long impulse response band-pass filter method to separate the sub-harmonic current and sub-harmonic voltage to be measured fro...

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Abstract

The present invention provides a harmonic electric energy measuring method, and belongs to the electric energy measuring technology filed. The method separates the basic wave coming from the signal of the voltage and the current of the power grid by a low-pass filter, separates the harmonic signal by a high-pass filter, then gets basic wave current and basic wave voltage as well as total harmonic current and total harmonic voltage; separates the total harmonic current and the total harmonic voltage to obtain a sub-harmonic current and a sub-harmonic voltage which need to be measured by an infinite impulse responding belt passing filter method; obtains different sub-harmonic current and sub-harmonic voltage of different times according to different harmonic frequencies to be measured; calculates various date of the power grid according to the basic wave current signal and the basic wave voltage signal. The spending of the present invention is less than that of the traditional rapid Fourier transform method.

Description

technical field [0001] The invention relates to a method for measuring harmonic electric energy, which belongs to the technical field of electric energy measurement. Background technique [0002] With the increasing number of high-power nonlinear loads such as electric locomotives and arcs in steelmaking on the power grid, the harmonic pollution of the power system is becoming more and more serious, which has caused great harm to the safe and economical operation of the power grid. Harmonic issues involve harmonic source analysis, distorted waveform analysis methods, harmonic compensation and suppression, harmonic limit standards and energy measurement under harmonics, etc. Electric energy measurement is the basis for three-party settlement between power generation enterprises, power transmission and transformation enterprises, and electricity customers. Under harmonic conditions, electric energy measurement cannot be calculated by the simple power algebraic sum used in trad...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R22/06G01R23/165
Inventor 门长有王荣华杨昆谭年熊
Owner HANGZHOU VANGO TECH
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