CN105717360A - Low-voltage single-phase harmonic impedance measuring method and device - Google Patents
Low-voltage single-phase harmonic impedance measuring method and device Download PDFInfo
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- CN105717360A CN105717360A CN201610052836.5A CN201610052836A CN105717360A CN 105717360 A CN105717360 A CN 105717360A CN 201610052836 A CN201610052836 A CN 201610052836A CN 105717360 A CN105717360 A CN 105717360A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/08—Measuring resistance by measuring both voltage and current
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Abstract
The invention discloses a low-voltage single-phase harmonic impedance measuring method and device. The method comprises that the network voltage of a grid connected point is obtained, and a required hth network harmonic voltage corresponding to the network voltage is extracted; a harmonic current is injected to the electrical network, the practical harmonic current is measured, the voltage of the grid connected point is obtained, and a required hth network harmonic voltage corresponding to the network voltage is extracted; and according to the hth network harmonic voltages extracted in two times and the measured practical harmonic current, the harmonic impedance of the electrical network is calculated. The method is highly operable, the harmonic impedance of a system can be obtained at any time and place, needed harmonic impedance of different orders can be obtained, the responsibility for harmonic pollution can be made clear, and electric energy quality detection and control of the power system are realized effectively.
Description
Technical field
The present invention relates to harmonic impedance field of measuring technique, particularly relate to a kind of single-phase harmonic impedance measuring method of low pressure and device.
Background technology
Along with industrial expansion, a large amount of nonlinear loads access electrical network, and to electrical network harmonic electric current, harmonic current flows through system impedance, form harmonic voltage, thus affecting the normal operation of sensitive load and equipment in electrical network on each bus.Further, along with a large amount of generations of harmonic wave, the pollution that harmonic wave produces also obtains the concern of people.The responsibility harmonic source causing harmonic wave accident to be punished accordingly, mains by harmonics level is played inhibiting user by those and to carry out corresponding award etc..And the premise that all these " rewards and punishments mechanism " realize is the harmonic pollution responsibility dividing each harmonic source reasonably and accurately, but divide the harmonic pollution responsibility of harmonic pollution source, it is necessary to harmonic voltage size that each harmonic source causes when appearing alone in this electrical network on bus or the proportion of harmonic voltage total shared by it.The harmonic contribution of each harmonic source of accurate quantification is even more important to distinguishing harmonic pollution responsibility, and embodying harmonic source with the causal parameter of bus harmonic voltage is the harmonic wave self-impedance of each node or internodal harmonic wave mutual impedance, therefore says and know that system impedance is particularly important for the responsibility distinguishing harmonic pollution.
In prior art, it is proposed that many methods about system harmonic impedance frequency characteristic measurement, but at present to this research on the one hand still in the theory analysis stage, it does not have research and develop the instrument measuring electric power networks harmonic impedance or equipment that can be applied to reality.At present, existing measuring method is divided into two big classes: the measuring method based on transient state and the measuring method based on stable state.Measuring method based on transient state is to extract harmonic impedance by the temporal variations of the transient voltage caused by measurement transient disturbance or electric current, and transient disturbance is outside injection to system or internal system generation.Measuring method based on stable state is the harmonic impedance utilizing the stable state waveform before and after system disturbance to determine system, and this disturbance canonic form is that the change by outside harmonic source internally harmonic electric current or the internal system method of operation is caused.
But all there is great defect in above two method, no matter carry out computing system harmonic impedance by transient disturbance or by the disturbance of stable state, all can only wait the disturbance from load side passively, both system harmonic impedance cannot have been known whenever and wherever possible, also required each harmonic impedance cannot be known, because the disturbance from load may not contain the harmonic current of required pendulous frequency, therefore actually it is difficult to meet the requirement of the modern power systems monitoring to the quality of power supply and control.
Summary of the invention
The embodiment of the present invention provides a kind of single-phase harmonic impedance measuring method of low pressure and device, to solve of the prior art cannot know system harmonic impedance whenever and wherever possible, the problem that also cannot know required each harmonic impedance.
In order to solve above-mentioned technical problem, the embodiment of the invention discloses following technical scheme:
The invention discloses a kind of single-phase harmonic impedance measuring method of low pressure, including:
Line voltage in acquisition site, and extract the h time mains by harmonics voltage needed for corresponding line voltage；
To electrical network harmonic electric current, measure actual harmonic current and obtain grid-connected point voltage, and extracting the h time mains by harmonics voltage needed for corresponding grid-connected point voltage；
According to the h time mains by harmonics voltage extracted for twice and the actual harmonic current recorded, calculate harmonic impedance in electrical network.
Preferably, the described the h time mains by harmonics voltage extracted needed for corresponding line voltage, specifically include: described corresponding line voltage is carried out Fourier decomposition process, obtains described the h time mains by harmonics voltage.
The h time mains by harmonics voltage needed for the corresponding grid-connected point voltage of described extraction, specifically includes: the grid-connected point voltage of described correspondence is carried out Fourier decomposition process, obtains described the h time mains by harmonics voltage.
Preferably, harmonic impedance in described calculating electrical network, including:
The difference of the h time mains by harmonics voltage that the corresponding line voltage of calculating and corresponding grid-connected point voltage extract respectively；
According to described difference and the actual harmonic current recorded, calculating described harmonic impedance, described calculating matrix includes: described difference is than upper described actual harmonic current.
Preferably, the size of the harmonic current injected to electrical network is adjustable.
Preferably, the value of described h is set to 2-50.
A kind of single-phase harmonic impedance measurement device of low pressure, including:
It is connected to the harmonic current generator on electrical network site, is used for electrical network harmonic electric current；
Accurate measurement instrument, described accurate measurement instrument is connected to electrical network two ends, for measuring harmonic voltage and the harmonic current at electrical network two ends；
Harmonic impedance computer, described harmonic impedance computer electrically connects with described accurate measurement instrument.
Preferably, described harmonic current generator is set to inverter.
Preferably, described accurate measurement instrument two ends are provided with high-voltage probe, and described high-voltage probe is connected to electrical network two ends, for detecting the harmonic voltage at electrical network two ends；
Described accurate measurement instrument also includes current probe, and described current probe is arranged on electrical network two ends, and described current probe is for detecting harmonic current actual in electrical network.
Preferably, described harmonic impedance computer includes digital signal processor, described digital signal processor for process accurate measurement instrument measurement to harmonic current and harmonic voltage calculate harmonic impedance.
Preferably, described device also includes display screen, and described display screen electrically connects with described harmonic impedance computer, and described display screen shows the harmonic current measured and harmonic voltage and the harmonic impedance calculated.
From above technical scheme, the single-phase harmonic impedance measuring method of low pressure that the embodiment of the present invention provides, method is easily understood, and workable.The single-phase harmonic impedance measurement device of low pressure that the embodiment of the present invention provides, including the harmonic current generator being connected on electrical network site, is used for electrical network harmonic electric current；Accurate measurement instrument, accurate measurement instrument is connected to electrical network two ends, for measuring harmonic voltage and the harmonic current at electrical network two ends；Harmonic impedance computer, harmonic impedance computer electrically connects with accurate measurement instrument.Accurate measurement instrument is provided with high-voltage probe and current probe, is respectively intended to harmonic voltage and the harmonic current at detection electrical network two ends.The disturbance from load side is waited without passive, it is possible to know system harmonic impedance whenever and wherever possible when using in the realistic case.
Accompanying drawing explanation
In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, the accompanying drawing used required in embodiment or description of the prior art will be briefly described below, apparently, for those of ordinary skills, under the premise not paying creative work, it is also possible to obtain other accompanying drawing according to these accompanying drawings.
The single-phase harmonic impedance measuring method schematic flow sheet of a kind of low pressure that Fig. 1 provides for the embodiment of the present invention；
The step S300 schematic flow sheet that Fig. 2 provides for the embodiment of the present invention；
The single-phase harmonic impedance measurement device structural representation of a kind of low pressure that Fig. 3 provides for the embodiment of the present invention；
In Fig. 3, symbol represents:
1-harmonic current generator, 2-accurate measurement instrument, 3-harmonic impedance computer, 4-high-voltage probe, 5-current probe.
Detailed description of the invention
The embodiment of the present invention provides a kind of single-phase harmonic impedance measuring method of low pressure and device, in order to make those skilled in the art be more fully understood that the technical scheme in the present invention, below in conjunction with the accompanying drawing in the embodiment of the present invention, technical scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is only a part of embodiment of the present invention, rather than whole embodiments.Based on the embodiment in the present invention, the every other embodiment that those of ordinary skill in the art obtain under not making creative work premise, all should belong to the scope of protection of the invention.
In order to make those skilled in the art be more fully understood that the present invention program, below in conjunction with accompanying drawing, the present invention is described in further detail.
First the method for the embodiment of the present invention is illustrated, referring to such as Fig. 1, for the single-phase harmonic impedance measuring method schematic flow sheet of a kind of low pressure that the embodiment of the present invention provides, including:
Preset: ushFor line voltage usH subharmonic voltage component；UhFor grid-connected point voltage ihH subharmonic voltage component；IhFor the h subharmonic current that harmonic current generator injects；ZhH subharmonic impedance for system
Step S100: the line voltage u in acquisition sites, and extract the h time mains by harmonics voltage u needed for corresponding line voltagesh；
Step S200: to electrical network harmonic electric current, measure actual harmonic current ihAnd obtain grid-connected point voltage ih, and extract corresponding grid-connected point voltage ihRequired h subharmonic voltage uh；
Step S300: the h time mains by harmonics voltage u extracted according to twiceshAnd uh, and the actual harmonic current i recordedh, calculate harmonic impedance Z in electrical networkh。
Referring to the step S300 schematic flow sheet that Fig. 2, Fig. 2 provide for the embodiment of the present invention, including:
Step S301: the line voltage u in acquisition sites, described corresponding line voltage is carried out Fourier decomposition process, obtains described the h time mains by harmonics voltage ush；
Step S302: to electrical network harmonic electric current, measure actual harmonic current ih, and obtain grid-connected point voltage ih, by the line voltage on described and site is carried out Fourier decomposition process, obtain described the h time mains by harmonics voltage uh；
Step S303: the difference of the h time mains by harmonics voltage that the corresponding line voltage of calculating and corresponding grid-connected point voltage extract respectively, i.e. uh-ush；
Step S304: according to described lookup and the actual harmonic current i that recordsh, described difference uh-ushWith described actual harmonic current ihRatio be the harmonic impedance Z in described electrical networkh。
Harmonic wave refers to the electricity of the integral multiple that frequency is first-harmonic contained in electric current, generally refers to periodic non-sine electricity is carried out Fourier space decomposition, all the other electricity produced more than the electric current of fundamental frequency.Fourier decomposition is the conventional means analyzing harmonic wave, and each periodic signal can be broken down into the superposition of the cycle sinusoidal signal of different frequency.The cycle sinusoidal signal of 50Hz is first-harmonic, and the signal of non-50Hz is called harmonic wave, if frequency is h times of 50Hz, is known as h subharmonic.
When calculating harmonic impedance, being sequentially adjusted in the frequency of harmonic current, make harmonic current frequency be harmonic wave h times, the value of h converts between 2-50, thus calculating the 2-50 subharmonic impedance of correspondence.
Corresponding with a kind of low pressure single-phase harmonic impedance measuring method embodiment provided by the invention, present invention also offers a kind of single-phase harmonic impedance measurement device of low pressure.
Referring to Fig. 3, for the single-phase harmonic impedance measurement device structural representation of a kind of low pressure that the embodiment of the present invention provides.
The single-phase harmonic impedance measurement device of low pressure that the present embodiment provides includes: harmonic current generator 1, accurate measurement instrument 2 and harmonic impedance computer 3.
Wherein, harmonic current generator 1 is connected on electrical network site, for injecting the harmonic current of certain frequency to electrical network.Harmonic current generator 1 is substantially an inverter.Harmonic current generator 1 can be switched on-off by control according to given instruction, controls the instruction current that output electric current can and then give.
Accurate measurement instrument 2 is connected to the two ends of electrical network, for measuring harmonic voltage and the harmonic current at electrical network two ends, is provided with high-voltage probe 4 on accurate measurement instrument 2, and high-voltage probe 4 is connected to the two ends of electrical network, can be used for detecting the harmonic voltage at electrical network two ends.It addition, be additionally provided with current probe 5 on accurate measurement instrument 2, current probe 5 is arranged on the two ends of electrical network and for measuring harmonic current actual in electrical network.
Harmonic impedance computer 3 connection electrically connects with accurate measurement instrument 2, and it can obtain accurate measurement instrument 2 and measure the harmonic current and harmonic voltage that arrive, and calculates accordingly.Harmonic impedance computer 3 includes digital signal processor, and digital signal processor can be used for processing accurate measurement instrument 2 and measures the harmonic current and harmonic voltage that arrive, and calculates harmonic impedance.Meanwhile, the data of digital signal processor processes also can be stored by harmonic impedance computer 3.
The harmonic impedance measurement device that the present embodiment provides also includes a display screen, and display screen electrically connects with harmonic impedance computer 3, and display screen is for showing the harmonic current measured, harmonic voltage and the harmonic impedance calculated.
Use procedure:
Loading onto accurate measurement instrument 2 at grid-connected point, but first do not install harmonic current generator 1, now, circuit disconnects, and that accurate measurement instrument 2 measures is line voltage us, after harmonic impedance computer 3 does Fourier decomposition, extract the h time required mains by harmonics voltage ush。
Loading onto harmonic current generator 1 at grid-connected point, and artificially arrange h times that frequency is first-harmonic of harmonic current, now, harmonic current generator 1 according to the requirement of instruction, can send the harmonic current i specifiedh。
Accurate measurement instrument 2 now records and the harmonic voltage of site is uhWith actual harmonic current ih。
To measure in the data input harmonics impedance computation device 3 obtained, then harmonic impedance can calculate the harmonic impedance Z of the h subharmonic of correspondence according to formulah。
It is sequentially adjusted in the value of h, just can obtain h time corresponding impedance.
As seen from the above-described embodiment, method provided by the invention and device can know system harmonic impedance whenever and wherever possible, and required each harmonic impedance can also be known, such that it is able to distinguish the responsibility of harmonic pollution, effectively realize the detection to electric power quality and control.
It should be noted that, in this article, the such as relational terms of " first " and " second " or the like is used merely to separate an entity or operation with another entity or operating space, and not necessarily requires or imply the relation that there is any this reality between these entities or operation or sequentially.And, term " includes ", " comprising " or its any other variant are intended to comprising of nonexcludability, so that include the process of a series of key element, method, article or equipment not only include those key elements, but also include other key elements being not expressly set out, or also include the key element intrinsic for this process, method, article or equipment.When there is no more restriction, statement " including ... " key element limited, it is not excluded that there is also other identical element in including the process of described key element, method, article or equipment.
The above is only the specific embodiment of the present invention, makes to skilled artisans appreciate that or realize the present invention.The multiple amendment of these embodiments be will be apparent to one skilled in the art, and generic principles defined herein can without departing from the spirit or scope of the present invention, realize in other embodiments.Therefore, the present invention is not intended to be limited to the embodiments shown herein, and is to fit to the widest scope consistent with principles disclosed herein and features of novelty.
Claims (10)
1. the single-phase harmonic impedance measuring method of low pressure, it is characterised in that including:
Line voltage in acquisition site, and extract the h time mains by harmonics voltage needed for corresponding line voltage；
To electrical network harmonic electric current, measure actual harmonic current and obtain grid-connected point voltage, and extracting the h time mains by harmonics voltage needed for corresponding grid-connected point voltage；
According to the h time mains by harmonics voltage extracted for twice and the actual harmonic current recorded, calculate harmonic impedance in electrical network.
2. the single-phase harmonic impedance measuring method of low pressure according to claim 1, it is characterised in that
The h time mains by harmonics voltage needed for the corresponding grid-connected point voltage of described extraction, specifically includes: the grid-connected point voltage of described correspondence is carried out Fourier decomposition process, obtains described the h time mains by harmonics voltage.
3. the single-phase harmonic impedance measuring method of low pressure according to claim 1, it is characterised in that harmonic impedance in described calculating electrical network, including:
The difference of the h time mains by harmonics voltage that the corresponding line voltage of calculating and corresponding grid-connected point voltage extract respectively；
According to described difference and the actual harmonic current recorded, calculating described harmonic impedance, described calculating matrix includes: described difference is than upper described actual harmonic current.
4. the single-phase harmonic impedance measuring method of low pressure according to claim 1, it is characterised in that adjustable to the size of the harmonic current of electrical network injection.
5. the single-phase harmonic impedance measuring method of low pressure according to claim 1, it is characterised in that the value of described h is set to 2-50.
6. the single-phase harmonic impedance measurement device of low pressure, it is characterised in that including:
It is connected to the harmonic current generator on electrical network site, is used for electrical network harmonic electric current；
Accurate measurement instrument, described accurate measurement instrument is connected to electrical network two ends, for measuring harmonic voltage and the harmonic current at electrical network two ends；
Harmonic impedance computer, described harmonic impedance computer electrically connects with described accurate measurement instrument.
7. the single-phase harmonic impedance measurement device of low pressure according to claim 6, it is characterised in that described harmonic current generator is set to inverter.
8. the single-phase harmonic impedance measurement device of low pressure according to claim 6, it is characterised in that described accurate measurement instrument two ends are provided with high-voltage probe, described high-voltage probe is connected to electrical network two ends, for detecting the harmonic voltage at electrical network two ends；
Described accurate measurement instrument also includes current probe, and described current probe is arranged on electrical network two ends, and described current probe is for detecting harmonic current actual in electrical network.
9. the single-phase harmonic impedance measurement device of low pressure according to claim 6, it is characterized in that, described harmonic impedance computer includes digital signal processor, described digital signal processor for process accurate measurement instrument measurement to harmonic current and harmonic voltage calculate harmonic impedance.
10. the single-phase harmonic impedance measurement device of low pressure according to claim 6, it is characterized in that, described device also includes display screen, and described display screen electrically connects with described harmonic impedance computer, and described display screen shows the harmonic current measured and harmonic voltage and the harmonic impedance calculated.
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| CN106908665A (en) * | 2017-02-10 | 2017-06-30 | 西南交通大学 | A kind of one-phase AC-system dq decomposes impedance measurement method |
| CN107390030A (en) * | 2017-07-26 | 2017-11-24 | 华南理工大学 | Three phase network harmonic impedance measuring method based on linear active disturbance rejection |
| CN108169585A (en) * | 2017-11-28 | 2018-06-15 | 国电南瑞科技股份有限公司 | One kind prejudges other division of responsibiltiy engineering method based on harmonic source |
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| EP3770615A1 (en) * | 2019-07-26 | 2021-01-27 | Analog Devices International Unlimited Company | Electrical network impedance determination |
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| CN108169585A (en) * | 2017-11-28 | 2018-06-15 | 国电南瑞科技股份有限公司 | One kind prejudges other division of responsibiltiy engineering method based on harmonic source |
| CN108169585B (en) * | 2017-11-28 | 2019-08-09 | 国电南瑞科技股份有限公司 | One kind prejudging other division of responsibiltiy engineering method based on harmonic source |
| CN109830985A (en) * | 2019-03-25 | 2019-05-31 | 阳光电源股份有限公司 | A kind of multi-machine parallel connection system and its electric network impedance detection method |
| EP3770615A1 (en) * | 2019-07-26 | 2021-01-27 | Analog Devices International Unlimited Company | Electrical network impedance determination |
| US11366149B2 (en) | 2019-07-26 | 2022-06-21 | Analog Devices International Unlimited Company | Electrical network impedance determination |
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