CN108169553A - Electric energy gauging method under the conditions of distorted signal based on wavelet transformation and curve matching - Google Patents
Electric energy gauging method under the conditions of distorted signal based on wavelet transformation and curve matching Download PDFInfo
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- CN108169553A CN108169553A CN201810020949.6A CN201810020949A CN108169553A CN 108169553 A CN108169553 A CN 108169553A CN 201810020949 A CN201810020949 A CN 201810020949A CN 108169553 A CN108169553 A CN 108169553A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R22/00—Arrangements for measuring time integral of electric power or current, e.g. electricity meters
- G01R22/06—Arrangements for measuring time integral of electric power or current, e.g. electricity meters by electronic methods
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Abstract
The invention belongs to field of power, disclose electric energy gauging method under the conditions of a kind of distorted signal based on wavelet transformation and curve matching.This method carries out decomposition and reconstruction first with wavelet transformation to power grid distorted voltage, current signal, obtain fundamental signal, recycle Fourier space that fundamental wave reconstruction signal carries out curve fitting, and the measured value of power grid fundamental voltage, electric current is obtained after normalization, finally subtract each other in original signal with the fundamental signal measured, power grid distorted voltage, current signal are obtained, and the data processing module for passing through electric energy metering device accurately calculates the numerical value of fundamental wave and the electric energy that distorts.Shock resistance electric energy metering device to research and develop suitable for power network signal Severe distortion situation provides solution.
Description
Technical field
The invention belongs to field of power, and power consumption power under the conditions of distorted signal can accurately be counted by being related to one kind
The method of amount, this method are highly effective to the accuracy aspect of electrical energy measurement under the conditions of enhancing distorted signal, have measurement error
It is small, the characteristics of accuracy of detection is not interfered by the wavelet decomposition number of plies.
Background technology
In modern power systems, with putting into operation for high-speed railway and extensive new-energy grid-connected inverter, make work
Industry nonlinear load increases sharply.The input of these nonlinear-loads is distorted network voltage, current signal waveform, makes
Power network signal contains a large amount of higher hamonic waves and impact variation ingredient, and severe jamming the accuracy of electrical energy measurement and fair and just original
Then.
It distorts under serious situation in current power network signal, how to improve electric energy metering device and counted under the conditions of distorted signal
The problem of accuracy of amount is very urgent.In order to solve this problem, there is an urgent need to one kind can be applied to distorted signal item
The multiprecision arithmetic of electrical energy measurement under part.
For this problem, there is researcher to achieve certain progress in terms of electrical energy measurement algorithm in recent years, it is existing to have
Several solutions below：
Improved fft algorithm.The method solves the problems, such as that fft algorithm is easily influenced by frequency fluctuation, but the method operation
Amount is very big, and real-time is comparatively poor, and also there are spectrum leakages and fence to show to the measurement of the m-Acetyl chlorophosphonazo of non-integer time
As etc., the measuring result error for leading to harmonic amplitude, phase angle and frequency is larger.
Complexification Newton-Cotes integral algorithms.The method has high-order measuring accuracy grade, can improve electrical energy measurement
Device electrical energy measurement accuracy under the conditions of distorted signal, although this method is not influenced, but by frequency variation to frequency
The comparable sensitivity of initial value once the Initial value choice of frequency is improper, will cause iteration not restrain, so as to increase measurement error
Add.
Currently, in the fresh approach of electrical energy measurement under the conditions of distorted signal, research is most wide and obtains remarkable break-throughs
It is the electric energy gauging method based on wavelet transformation.But the testing result of this method is easily influenced by the wavelet decomposition number of plies, different decomposition
The number of plies, detection error are very big.
In conclusion electric energy gauging method respectively has advantage and disadvantage under the conditions of existing distorted signal, in practical application not
Accurate Measurements of Electric Energy under the unsteady-state distortions signal conditioning such as impact signal can be effectively solved the problems, such as, it is therefore proposed a kind of measurement
Error is small, and accuracy of detection is not influenced by the wavelet decomposition number of plies, while can meet again under the unsteady-state distortions signal such as impact signal temporarily
The metering method that state electrical energy measurement needs has great theory significance and engineering application value.
Invention content
The present invention carries out decomposition and reconstruction first with wavelet transformation to power grid distorted voltage, current signal, obtains fundamental wave
Signal, then Sine-Fitting is carried out, and power grid is obtained after normalization by obtained fundamental signal is reconstructed by Fourier space
The measured value of fundamental voltage, current signal finally subtracts the fundamental signal measured in the original distorted signal of power grid, obtains power grid
Distorted voltage, current signal, and the data processing module for passing through metering device accurately calculates fundamental wave and the numerical value of distortion power.It should
Method can reasonably and accurately measure the fundamental wave and distortion power in the case of power network signal Severe distortion, and small with measurement error,
The characteristics of real-time is good, and accuracy of detection is not influenced by the wavelet decomposition number of plies.
To achieve the above object, technical scheme of the present invention includes the following steps：
1) first, pass through the power grid distorted voltage and electricity under the conditions of the data collecting module collected distorted signal of metering device
Stream；
2) secondly, using obtained power grid distorted voltage and electric current as input signal, pass through Mallat Algorithm of Wavelet Transform
Multilayer decomposition is carried out to power grid unsteady-state distortion signal, extracts power grid fundamental signal；
3) obtained fundamental signal then, is subjected to fourier series reconstruct and curve matching, is further reduced because small
Wave conversion Decomposition order is undesirable to lead to reconstruct gained fundamental signal wave distortion；
4) finally, for the amplitude of signal and the amplitude of original fundamental signal after fitting is made to be more nearly, then pass through normalization
Fundamental wave fitted signal is normalized in method, improves the accuracy of fundamental signal extraction, and passes through at the data of metering device
Reason module accurately calculates fundamental wave and the numerical value of distortion power.
Electric energy gauging method is beneficial under the conditions of the distorted signal based on wavelet transformation and curve matching that the present invention announces
Effect is：
Quickly it can detect and extract fundamental signal and distorted signal in network deformation signal and carry out accurate rational electricity
It can measure, by using the method that wavelet transformation and curve matching are combined, overcome signal detection precision easily by wavelet decomposition
The shortcomings that number of plies influences, and detection real-time performance is poor solves the transient state electricity under the unsteady-state distortions signal conditioning such as impact signal
Energy measurement problem, while to research and develop the data and advanced in technology that the scope of application is wider, metering more reasonably electric energy meter provides basis.
In order to make technical scheme of the present invention, objects and advantages clearer, the present invention is done below in conjunction with attached drawing into
The description of one step.
Description of the drawings
Fig. 1 is electric energy metering device functional block diagram under the conditions of distorted signal.
Fig. 2 is Mallat algorithm wavelet decomposition process schematics.
Fig. 3 is electrical energy measurement flow chart under the conditions of distorted signal.
Specific embodiment
Below in conjunction with the accompanying drawings the distorted signal item proposed by the present invention based on wavelet transformation and curve matching is illustrated with example
Electric energy gauging method under part.
In modern power systems, the high-power silicon rectifying equipment of electric railway and electrolysis plant, AC inverter etc.
The extensive use of power electronic equipment makes industrial nonlinear load increase sharply.The operation of these loads, leads to power grid electric energy matter
Amount deteriorates increasingly, signal waveform Severe distortion, and power network signal is made to have the complicated spy such as harmonic wave, m-Acetyl chlorophosphonazo, voltage and electric current drastic change
Property, the accuracy and reasonability of electrical energy measurement are directly affected, is made based on sinusoidal current Power Theory or traditional Nonsinusoidal Circuits
The electric energy measurement instrument of Power Theory design cannot really reflect the electric energy that load is absorbed from electric system, can not be accurate
Reasonably measure electric energy.Wherein, the simplified model under the conditions of distorted signal is believed in power grid as shown in Figure 1, illustrated with this model
Number distortion in the case of, network voltage, electric current composition and power flow distribution.
In Fig. 1, u (t) represents network voltage, it is assumed that is constant sinusoidal voltage；I (t) is the electric current for flowing through this circuit；Z1For
Line impedance；Z is non-linear, impact load；A is electric energy loaded metering node.
In Fig. 1, a point u (t), i (t) can be expressed as：
Wherein：uI(t) and iI(t) it is fundametal compoment, us(t) and is(t) it is allocation of distortion；
Line impedance voltage is represented by：
Δ u (t)=Δ uI(t)+Δus(t) (3)
Wherein, Δ uI(t)、Δus(t) be respectively line impedance voltage fundamental wave and allocation of distortion.
And pass through the power that the electrical energy measurement node a in circuit calculates nonlinear load consumption, meanwhile, work(is measured to a points
Rate carries out tidal current analysis；
The instantaneous power that a points can be obtained by Power Theory is：
pa(t)=ua(t)ia(t) (4)
Formula (1), formula (2) are substituted into formula (3) and obtained：
pa(t)=[uI(t)+us(t)][iI(t)+is(t)]
=uI(t)iI(t)+uI(t)is(t)
+us(t)iI(t)+us(t)is(t)
=pI(t)+pIs(t)+psI(t)+ps(t) (5)
The mean power of a points is：
In formula:PI、PIs、PsIWith PsThe respectively fundamental power of nonlinear scale spaces load absorption, fundamental voltage and distortion
The power that the power and distorted voltage that power, distorted voltage and the fundamental current that electric current generates generate are generated with distortion current.
This, claims PsFor distortion power.
Wherein, PIs≥0；PsI≤ 0, but the feedback grid in a manner of fundamental current, pollution is not generated to power grid, it should receive
Enter metering；PsPerseverance is negative value, and the feedback grid in a manner of distortion current, generates pollution to power grid, should not be included in metering.
Therefore, the power P rationally measured should be：
P=PI+PIs+PsI-Ps
=Pa-Ps (7)
PaFor practical measurement power, the P at metering node asFor PaIn distortion power；From the above equation, we can see that realize Reasonable
The key of amount is to be precisely separating out by the distortion power measured in power.
As shown in Fig. 2, electrical energy measurement under the conditions of the distorted signal proposed by the present invention based on wavelet transformation and curve matching
Method includes the following steps：
Step 1：Multi-scale wavelet decomposition is carried out to power grid distorted signal and extracts fundamental signal
In power grid distorted signal detection field, if u (t) is the power grid distorted signal to be analyzed herein, become using small echo
It changes Mallat algorithms and multilayer decomposition is carried out to power grid unsteady-state distortion signal, extract power grid fundamental signal.Its decomposition algorithm can
It is expressed as：
T in formulaiFor discrete-time series, u (ti) it is original signal, j is Decomposition order, and k is scale coefficient, and H, G are time domain
Wavelet analysis wave filter；AjFor signal u (ti) in the low frequency coefficient of jth layer, DjFor signal u (ti) in the high frequency coefficient of jth layer.
Corresponding decomposable process is as shown in Figure 2.
Step 2：Fourier series reconstruct and curve matching are carried out to the fundamental signal of extraction
Wavelet transformation Decomposition order is more, will make that the low frequency coefficient loss of learning for obtaining fundamental signal should be reconstructed, lead
Cause reconstruct gained fundamental signal wave distortion.The high fundamental wave of the degree of consistency and abnormal could be obtained by only reaching best Decomposition order
Varying signal, but true signal distortion degree is different, and the best Decomposition order under different situations is also unknown.Therefore, this hair
It is bright that the fundamental signal that wavelet decomposition obtains carries out curve fitting, fundamental signal according to Fourier space is unfolded, is fitted
Method is as follows：
Wherein, a0、ak、bkFor Fourier coefficient, w is frequency；Since the fundamental signal of perfect condition is believed for standard sine
Number, as long as so wavelet transformation is reconstructed gained by the coefficient retention constant item of Fourier space and 1 order harmonic components
Fundamental signal is to standard sine signal fitting.Acquire the fundamental signal u after curve matchingI" (t) be：
uI" (t)=a0+a1cos(kωt)+b1sin(kωt) (10)
Step 3：Fundamental wave fitted signal is normalized, obtains the measured value of power grid fundamental voltage, current signal
For the amplitude of signal and the amplitude of original fundamental signal after fitting is made to be more nearly, then by method for normalizing to base
Wave fitted signal is normalized, and improves the accuracy of fundamental signal extraction.Wherein：
Step 4：Power grid distorted voltage, current signal are extracted, and the data processing module for passing through metering device accurately calculates
The numerical value of fundamental wave and distortion power
It is finally, former in power grid by the power grid fundamental voltage obtained after normalization, the measured value of current signal such as Fig. 3
The fundamental signal measured is subtracted in beginning distorted signal, obtains power grid distorted voltage, current signal, and pass through electric energy metering device
Data processing module accurately calculates fundamental wave and the numerical value of distortion power.
The present invention quickly can detect and extract fundamental signal in network deformation signal and distorted signal is accurately closed
The electrical energy measurement of reason by using the method that wavelet transformation and curve matching are combined, overcomes signal detection precision easily by small
The shortcomings that Wave Decomposition number of plies influences, and detection real-time performance is poor, solves under the unsteady-state distortions signal conditioning such as impact signal
Transient power measurement problem, while to research and develop the data and skill that the scope of application is wider, metering more reasonably electric energy meter provides basis
Art guide.
Above example is only to illustrate invention, it is evident that the present invention is not limited to these embodiments restrictions.This field
Modification, deformation or the equivalent replacement of any substantive content based on the present invention of those of ordinary skill, are encompassed by right of the present invention
In claimed range.
The content not being described in detail in this specification belongs to the prior art well known to professional and technical personnel in the field.
Claims (5)
1. electric energy gauging method under the conditions of a kind of distorted signal based on wavelet transformation and curve matching, which is characterized in that utilize
Wavelet transformation carries out decomposition and reconstruction to power grid distorted voltage, current signal, obtains fundamental signal, recycles Fourier space will
Fundamental wave reconstruction signal carries out curve fitting, and the measured value of power grid fundamental voltage, electric current is obtained after normalization, finally in original
Subtract each other in beginning signal with the fundamental signal measured, obtain power grid distorted voltage, current signal, and pass through the number of electric energy metering device
The numerical value of fundamental wave and the electric energy that distorts accurately is calculated according to processing module.To research and develop the anti-impact suitable for power network signal Severe distortion situation
It hits electric energy metering device and provides solution.
2. electric energy gauging method under the conditions of the distorted signal according to claim 1 based on wavelet transformation and curve matching,
It is characterized in that, the electric energy metering device is mainly made of slave computer and host computer.
3. electrical energy measurement side under the conditions of the distorted signal according to claim 1 or 2 based on wavelet transformation and curve matching
Method, which is characterized in that the slave computer includes data acquisition module and communication interface, and main data acquisition and data are led to
Telecommunication function；The host computer is made of data processing, data management and data communication interface modules three parts.
4. electrical energy measurement side under the conditions of the distorted signal based on wavelet transformation and curve matching according to claim 1 or 3
Method, which is characterized in that the data processing module is substantially carried out the wavelet function feedback of power grid distorted voltage, current signal,
And fundamental energy, distortion electric energy and the rationally calculating of metering power, the functions such as data storage, data management and real-time mapping.
5. electric energy gauging method under the conditions of the distorted signal according to claim 4 based on wavelet transformation and curve matching,
It is characterized in that, the reasonable metering power, i.e.,：
P=PI+PIs+PsI-Ps=Pa-Ps (1)
Wherein, PaFor practical measurement power, the P at metering node asFor PaIn distortion power.
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| CN109557509A (en) * | 2018-11-23 | 2019-04-02 | 安徽四创电子股份有限公司 | It is a kind of for improving the dipulse signal synthesizer interfered between arteries and veins |
| CN111624399A (en) * | 2020-06-12 | 2020-09-04 | 国网上海市电力公司 | Electric energy metering method and system for nonlinear load |
| CN112630527A (en) * | 2020-12-04 | 2021-04-09 | 云南民族大学 | Distortion signal electric quantity measuring method based on empirical wavelet transform |
| CN113884758A (en) * | 2021-09-29 | 2022-01-04 | 广东电网有限责任公司 | Direct current electric energy metering method, device, equipment and storage medium |
| CN117330831A (en) * | 2023-08-24 | 2024-01-02 | 国网安徽省电力有限公司营销服务中心 | Electric energy metering method and system for nonlinear load |
| CN117388569A (en) * | 2023-12-11 | 2024-01-12 | 浙江宏仁电气有限公司 | Electric energy metering method, electric energy metering box and medium under waveform distortion of power grid |
| JP7467495B2 (en) | 2019-03-22 | 2024-04-15 | ランディス・ギア イノベーションズ インコーポレイテッド | Validation of Fundamental-only Energy Measurement |
| CN117951502A (en) * | 2024-03-26 | 2024-04-30 | 国网江苏省电力有限公司苏州供电分公司 | Intelligent park collection-oriented electricity consumption pretreatment device and method |
| CN117951502B (en) * | 2024-03-26 | 2024-05-31 | 国网江苏省电力有限公司苏州供电分公司 | Intelligent park collection-oriented electricity consumption pretreatment device and method |
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| CN109557509A (en) * | 2018-11-23 | 2019-04-02 | 安徽四创电子股份有限公司 | It is a kind of for improving the dipulse signal synthesizer interfered between arteries and veins |
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| JP7467495B2 (en) | 2019-03-22 | 2024-04-15 | ランディス・ギア イノベーションズ インコーポレイテッド | Validation of Fundamental-only Energy Measurement |
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| CN117330831A (en) * | 2023-08-24 | 2024-01-02 | 国网安徽省电力有限公司营销服务中心 | Electric energy metering method and system for nonlinear load |
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| CN117951502A (en) * | 2024-03-26 | 2024-04-30 | 国网江苏省电力有限公司苏州供电分公司 | Intelligent park collection-oriented electricity consumption pretreatment device and method |
| CN117951502B (en) * | 2024-03-26 | 2024-05-31 | 国网江苏省电力有限公司苏州供电分公司 | Intelligent park collection-oriented electricity consumption pretreatment device and method |
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