CN109617443A - A kind of gird-connected inverter output current sample control method - Google Patents
A kind of gird-connected inverter output current sample control method Download PDFInfo
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- CN109617443A CN109617443A CN201811543062.1A CN201811543062A CN109617443A CN 109617443 A CN109617443 A CN 109617443A CN 201811543062 A CN201811543062 A CN 201811543062A CN 109617443 A CN109617443 A CN 109617443A
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- gird
- connected inverter
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- electric current
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
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- Power Engineering (AREA)
- Inverter Devices (AREA)
Abstract
The present invention relates to a kind of gird-connected inverters to export current sample control method, this method are as follows: the output electric current of gird-connected inverter is sampled and obtained using frequency multiplication sample mode in PWM switch periods multiple sampled values of the rising edge and failing edge that respectively correspond output electric current, and calculate the average current value of multiple sampled values, using average current value as the feedback current of the exchange side control system of gird-connected inverter, and series connection anticipatory control link corresponding with feedback current is set in the exchange side control system of gird-connected inverter, to realize the controlling of sampling to gird-connected inverter output electric current.The present invention solves the problems, such as the midpoint sample of gird-connected inverter output, can improve power quality, it is higher to avoid result in second harmonic.
Description
Technical field
The invention belongs to power electronics fields, and in particular to one kind is applied in gird-connected inverter to export electricity to it
The method that stream carries out controlling of sampling.
Background technique
Fig. 1 show common single-phase two-stage type photovoltaic combining inverter structure, wherein exchange side control system block diagram is such as
Shown in Fig. 2, control is double -loop control, and outer ring Voltage loop controls DC bus UdcVoltage, inner ring current loop control inverter are defeated
Electric current I outout。
Electric current loop routine is all same frequency sampling, i.e. sampling period=PWM switch periods.Fig. 3 is PWM duty cycle of switching D
With corresponding inductive current ILCorresponding relationship.Under same frequency sampling mode, in order to eliminate inductive current ILCurrent ripples shadow
It rings, the sampling instant of electric current can be artificially adjusted in design, it would be desirable to sample the midpoint T of inductive current0The current value at moment.So
And by sampling time delay, the influence of the transfer delay of controller ADC chip is actually difficult to sample midpoint T0Moment can adopt
Distance T0The T of deviation delta T1Moment, Δ T here are delayed by aforementioned sample, and the combined influence of ADC chip transfer delay can not disappear
It removes, while being also difficult to compensate.
Because of the presence of Δ T, lead to not the midpoint sample for realizing electric current, therefore, the electric current being input in electric current loop is anti-
Feedback value unavoidably introduces current ripples, and for controlling precision, control performance has very important influence, here by shadow
Maximum second harmonic is rung to illustrate.
Gird-connected inverter is as equipment of generating electricity by way of merging two or more grid systems, and harmonic current needs to meet the requirement of power grid standard, with domestic energy
For marking NB-T 32004-2013 " technical specification of photovoltaic power generation grid-connected inverter ", requirement such as Fig. 4 for harmonic wave, from
It can be seen that, the requirement for even-order harmonic is most stringent in figure.
And because cannot achieve midpoint sample, the inductive current that inverter samples includes ripple current ingredient, and inductance
Electric current is connected to the grid after filtering as output electric current, this output electric current is not comprising ripple current ingredient, therefore
The inductive current that inverter samples is practical to be not equal to output electric current, and sampling time delay Δ T is bigger or inductive current ripple is bigger,
This difference is more obvious, and the second harmonic for exporting electric current is caused to transfinite.It is the electric current R sampled shown in Fig. 5sampWith it is actual defeated
Electric current R outphaDifference between Real, it can be seen that causing actual output electric current to be sent out because cannot achieve midpoint sample
It is raw " inclined head " phenomenon, i.e. the inverter electric current wave crest (or trough) sampled and the wave crest (or trough) of actual output current are no
Unanimously.And Fig. 6 is that Harmonic characteristic analysis is carried out to the ingredient of output electric current, analysis result is that output electric current includes 50Hz sinusoidal quantity
With 100Hz sinusoidal quantity, the second harmonic that this extra 100Hz sinusoidal quantity will lead to output electric current is higher.
It can be seen that how to realize to output electric current midpoint sample it is most important, will affect the electric energy matter of output
Amount.
Summary of the invention
The object of the present invention is to provide a kind of midpoints for being able to solve gird-connected inverter to use problem, to improve electric energy matter
The gird-connected inverter of amount exports current sample control method.
In order to achieve the above objectives, the technical solution adopted by the present invention is that:
A kind of gird-connected inverter output current sample control method, this method are as follows: adopted in PWM switch periods using frequency multiplication
Sample loading mode samples the output electric current of gird-connected inverter and obtains the rising edge for respectively corresponding the output electric current and decline
Multiple sampled values on edge, and the average current value of multiple sampled values is calculated, using the average current value as described grid-connected
Inverter exchange side control system feedback current, and in the exchange side control system of the gird-connected inverter setting with
The corresponding series connection anticipatory control link of the feedback current, to realize the sampling control to gird-connected inverter output electric current
System.
Preferably, the frequency sampled to the output electric current of the gird-connected inverter is 2 times of PWM switching frequency.
Due to the above technical solutions, the present invention has the following advantages over the prior art: the present invention solves simultaneously
The midpoint sample problem of net inverter output, can improve power quality, it is higher to avoid result in second harmonic.
Detailed description of the invention
Attached drawing 1 is single-phase two-stage type photovoltaic combining inverter structural schematic diagram.
Attached drawing 2 is that gird-connected inverter exchanges side control system block diagram.
Attached drawing 3 is PWM duty cycle of switching D and corresponding inductive current ILCorrespondence diagram.
Attached drawing 4 is the requirement in national standard for harmonic wave.
Attached drawing 5 is the difference schematic diagram between the electric current sampled using existing method and actual output electric current.
Attached drawing 6 is the Harmonic characteristic analysis figure for exporting the ingredient of electric current.
Attached drawing 7 is that gird-connected inverter of the invention exports the schematic diagram sampled in current sample control method.
Attached drawing 8 is the exchange side using the gird-connected inverter of gird-connected inverter output current sample control method of the invention
Control system schematic diagram.
Specific embodiment
The invention will be further described for embodiment shown in reference to the accompanying drawing.
Embodiment one: a kind of gird-connected inverter output current sample control method, this method are as follows: in PWM switch periods
It is sampled using output electric current of the frequency multiplication sample mode to gird-connected inverter and obtains the rising edge for respectively corresponding output electric current
With multiple sampled values of failing edge, and the average current value of multiple sampled values is calculated, using average current value as gird-connected inverter
Exchange side control system feedback current, and in the exchange side control system of gird-connected inverter setting and feedback current
Corresponding series connection anticipatory control link, to realize the controlling of sampling to gird-connected inverter output electric current.
Specifically, sampling is changed to the frequency by frequency sampling, sampled to the output electric current of gird-connected inverter from same frequency sampling
Rate is 2 times of PWM switching frequency, and sample frequency=PWM switch periods * 2, each PWM switch periods are interior to sample inverter twice
Outputting inductance electric current.The two outputting inductance electric currents of sampling need to adjust in the rising edge and failing edge of output electric current respectively
Sampling instant, it is therefore intended that sampled respectively at the midpoint of rising edge of output electric current and the midpoint of failing edge.But since sampling is prolonged
When presence, as shown in Fig. 7, rising edge the actual samples moment be T1, sample electric current T1, and in the reality of failing edge
Sampling instant is T2, sample electric current T2.Then, it utilizes
Calculate average current value I0, by this average current value I0As in gird-connected inverter exchange side control system it is anti-
Feedback input.Because Δ T in the influence of rising edge and failing edge to sampled value be it is opposite,, can by the calculating of formula 1
To allow Δ T to cancel out each other in the influence of rising edge and failing edge, therefore the midrange of real inductive current can be obtained, also
Solve it is aforementioned can not midpoint sample bring influence.
But because of times frequency sampling, lead to the current sampling data of loop, that is, the average current value I fed back0Will failing edge it
After could update, and originally with frequency sampling renewable time be rising edge midpoint T0Near moment, then need in failing edge now
Point T3Near, the delay of loop is increased, therefore, it is necessary to increase phase compensation link in control loop, that is, advanced school of connecting
Positive link.Loop control structure such as Fig. 8, G in figure of exchange side control system after improvement0It (S) is that a times frequency sampling causes to introduce
The delay of loop, G1It (S) is for the increased series connection anticipatory control link that is delayed.
The effect of above scheme is the midpoint sample that can guarantee to export electric current, defeated for improving grid-connected photovoltaic inverter
Power quality out, especially to output is solved the problems, such as, electric current second harmonic is higher important meaning.
The above embodiments merely illustrate the technical concept and features of the present invention, and its object is to allow person skilled in the art
Scholar cans understand the content of the present invention and implement it accordingly, and it is not intended to limit the scope of the present invention.It is all according to the present invention
Equivalent change or modification made by Spirit Essence, should be covered by the protection scope of the present invention.
Claims (2)
1. a kind of gird-connected inverter exports current sample control method, it is characterised in that: the gird-connected inverter output electric current is adopted
Sample control method are as follows: using frequency multiplication sample mode the output electric current of gird-connected inverter is sampled in PWM switch periods and
Multiple sampled values of the rising edge and failing edge that respectively correspond the output electric current are obtained, and calculate the flat of multiple sampled values
Equal current value, using the average current value as the feedback current of the exchange side control system of the gird-connected inverter, and
Series connection anticipatory control link corresponding with the feedback current is set in the exchange side control system of the gird-connected inverter, from
And realize the controlling of sampling to gird-connected inverter output electric current.
2. a kind of gird-connected inverter according to claim 1 exports current sample control method, it is characterised in that: to described
The frequency that the output electric current of gird-connected inverter is sampled is 2 times of PWM switching frequency.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110086197A (en) * | 2019-04-18 | 2019-08-02 | 江苏固德威电源科技股份有限公司 | Inductive current sampling calculation method |
| CN112600406A (en) * | 2020-11-04 | 2021-04-02 | 国网浙江绍兴市上虞区供电有限公司 | DCDC converter control device and method based on cross trigger unit sampling |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106992661A (en) * | 2017-04-17 | 2017-07-28 | 广西大学 | The over-sampling real-time signal processing method controlled for PWM count word |
| CN108631629A (en) * | 2018-02-28 | 2018-10-09 | 南京航空航天大学 | Improve a kind of phase lead compensation method of LCL type gird-connected inverter robustness |
-
2018
- 2018-12-17 CN CN201811543062.1A patent/CN109617443A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106992661A (en) * | 2017-04-17 | 2017-07-28 | 广西大学 | The over-sampling real-time signal processing method controlled for PWM count word |
| CN108631629A (en) * | 2018-02-28 | 2018-10-09 | 南京航空航天大学 | Improve a kind of phase lead compensation method of LCL type gird-connected inverter robustness |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110086197A (en) * | 2019-04-18 | 2019-08-02 | 江苏固德威电源科技股份有限公司 | Inductive current sampling calculation method |
| CN110086197B (en) * | 2019-04-18 | 2022-07-19 | 固德威技术股份有限公司 | Inductive current sampling calculation method |
| CN112600406A (en) * | 2020-11-04 | 2021-04-02 | 国网浙江绍兴市上虞区供电有限公司 | DCDC converter control device and method based on cross trigger unit sampling |
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Address after: 215000 No. 90, Zijin Road, high tech Zone, Suzhou, Jiangsu Applicant after: Goodway Technology Co.,Ltd. Applicant after: GOODWE POWER SUPPLY TECHNOLOGY (GUANGDE) Co.,Ltd. Address before: 215163 No.189 Kunlunshan Road, high tech Zone, Suzhou City, Jiangsu Province Applicant before: JIANGSU GOODWE POWER SUPPLY TECHNOLOGY Co.,Ltd. Applicant before: GOODWE POWER SUPPLY TECHNOLOGY (GUANGDE) Co.,Ltd. |
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