CN107947240A - A kind of island detection method of droop control gird-connected inverter - Google Patents
A kind of island detection method of droop control gird-connected inverter Download PDFInfo
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- CN107947240A CN107947240A CN201711389264.0A CN201711389264A CN107947240A CN 107947240 A CN107947240 A CN 107947240A CN 201711389264 A CN201711389264 A CN 201711389264A CN 107947240 A CN107947240 A CN 107947240A
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- 238000001514 detection method Methods 0.000 title claims abstract description 11
- 238000007665 sagging Methods 0.000 claims abstract description 23
- 238000012544 monitoring process Methods 0.000 claims abstract description 17
- 230000006872 improvement Effects 0.000 claims abstract description 6
- 238000000034 method Methods 0.000 claims abstract description 6
- 230000008859 change Effects 0.000 claims description 8
- 230000010354 integration Effects 0.000 abstract 1
- 238000005516 engineering process Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 238000011217 control strategy Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 230000009897 systematic effect Effects 0.000 description 1
Classifications
-
- H02J3/382—
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/388—Islanding, i.e. disconnection of local power supply from the network
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Inverter Devices (AREA)
Abstract
The invention discloses a kind of island detection method of droop control gird-connected inverter, specifically implement according to following steps：Step 1, structure three-phase grid-connected inverter main circuit system；Step 2, the active power of output and reactive power for calculating three-phase grid-connected inverter；Step 3, utilize addition disturbance k (f fgThe improvement P f droop control devices of)/s calculate the reference output of voltage magnitude and phase.Step 4, by reference voltage and phase and virtual voltage and phase obtain error voltage value as difference, reference input as outer shroud adjuster, the output of adjuster is the reference input of interior circular current, again error current value is obtained as difference with actual current, as the input of inner ring adjuster, output modulated signal is finally obtained；Step 5, in real time monitoring | d Δs θ/dt |=| k (f fg) | value carry out isolated island judgement.The present invention disturb part on the basis of traditional isolated island monitors sagging improved method and adds integration, is not only increased | d Δs θ/dt | amplitude and also its amplitude is maintained stable amplitude, so as to avoid isolated island erroneous judgement.
Description
Technical field
The present invention relates to power grid detection field, the micro-capacitance sensor isolated island monitoring method of especially a kind of droop control.
Background technology
With the development of renewable energy power generation technology, distributed generation technology comes into being.Droop control in recent years
Inverter is due to having the advantages that " plug and play ", need not communicate, using more and more extensive in distributed generation system.Micro-
Grid-connected and two kinds of situations of isolated island can be run into during network operation, island effect refers to when electric system is stopped power supply because of failure,
Distributed generation system continues to provide the active and phenomenon of reactive power to local load, and isolated island is divided into planned isolated island and non-again
Planned isolated island.It is critically important to the monitoring accuracy and speed of unplanned property isolated island.It is so necessary to being commonly used
The isolated island monitoring of sagging microgrid control program is studied.
For traditional piconet island monitoring scheme based on droop control, not only it is not easy to monitor but also is also easy to miss
Sentence.Prevent isolated island monitoring result is from reaching gratifying result.
The content of the invention
Present invention aims at provide a kind of isolated island inspection for monitoring droop control gird-connected inverter easy, that monitoring error is low
Survey method.
To achieve the above object, following technical scheme is employed：The method of the invention comprises the following steps：
Step 1, three-phase grid-connected inverter main circuit system is built；
Step 2, the active power of output and reactive power of three-phase grid-connected inverter are calculated；
Step 3, addition disturbance k (f-f are utilizedgThe improvement droop control device of)/s calculates voltage magnitude and the reference of phase is defeated
Go out；K is proportionality coefficient in formula, and f is the frequency of sagging output, fgFor mains frequency, s is pull-type operator.
Step 4, reference voltage and phase are obtained into error voltage value as difference with virtual voltage and phase, is adjusted as outer shroud
The reference input of device, the output of adjuster is the reference input of interior circular current, then obtains error current value as difference with actual current,
As the input of inner ring adjuster, the output finally obtained is modulated signal；
Step 5, monitoring in real time | d Δs θ/dt |=| k (f-fg) | value carry out isolated island judgement.K is proportionality coefficient in formula, f
For the frequency of sagging output, fgFor mains frequency, Δ θ is phase place change.
Further, in step 1, three-phase main circuit structure uses three-phase half-bridge structure and LC filter structures.
Further, in step 3, the angle of traditional isolated island monitoring P-f droop control devices is exported
It is changed into
Obtain：
In formula, P exports actual active power, P for inverter*For given active power, m is sagging coefficient, f*To be sagging
Given frequency, f'=f, f are sagging output frequency, fgFor the actual frequency of power grid, θ ' is the angle of sagging final output, k
=2 π k'.K is proportionality coefficient in formula, and s is pull-type operator.
Further, in step 5, monitoring in real time | d Δs θ/dt |=| k (f-fg) | value, when its value is stationary value, as
Judge the foundation that isolated island occurs.
Compared with prior art, the invention has the advantages that：
1st, distracter is integrated, is increased | d Δs θ/dt | change amplitude, isolated island is had larger width when occurring
Value change, monitoring are easier.
2nd, disturbance quantity is added on sagging curve, system integrally still has droop characteristic.
3rd, detection limit is increased, and there is filter action and low pass effect, is conducive to suppress interference, enhances isolated island monitoring
Accuracy.
Brief description of the drawings
Fig. 1 is the control strategy structure chart of inverter.
Fig. 2 is improvement droop control structured flowchart.
Fig. 3 is the equivalent-simplification figure for Fig. 2.
Fig. 4 is the phase difference and its change rate after frequency disturbance between inverter and power grid when being incorporated into the power networks.
Fig. 5 is PCC dot frequency offsets f-fg, | d Δs θ/dt |, isolated island detection signal graph.
Embodiment
The present invention will be further described below in conjunction with the accompanying drawings：
The method of the invention comprises the following steps：
Step 1, three-phase grid-connected inverter main circuit system is built；Three-phase main circuit structure uses three-phase half-bridge structure and LC
Filter structure.
Step 2, the active power of output and reactive power of three-phase grid-connected inverter are calculated；
Step 3, addition disturbance k (f-f are utilizedgThe improvement droop control device of)/s calculates voltage magnitude and the reference of phase is defeated
Go out；K is proportionality coefficient in formula, for the frequency of sagging output, fgFor mains frequency, s is pull-type operator.
Improved sagging phase angle, which exports, is：
It is hereby achieved that new is sagging：F'=f*-m(P-P*)+k'(f'-fg)
Deformation obtains：
In formula, P exports actual active power, P for inverter*For given active power, m is sagging coefficient, f*To be sagging
Given frequency, f'=f, f are sagging output frequency, fgFor the actual frequency of power grid, θ ' is the angle of sagging final output, k
=2 π k'.K is proportionality coefficient, in order to which the statement of above-mentioned expression formula facilitates the introduction of k' in formula, and s is pull-type operator.Such as the institute of Fig. 1,2,3
Show.
Step 4, reference voltage and phase are obtained into error voltage value as difference with virtual voltage and phase, is adjusted as outer shroud
The reference input of device, the output of adjuster is the reference input of interior circular current, then obtains error current value as difference with actual current,
As the input of inner ring adjuster, the output finally obtained is modulated signal；
Step 5, monitoring in real time | d Δs θ/dt |=| k (f-fg) | value carry out isolated island judgement, when its value be stationary value, work
To judge the foundation of isolated island generation.K is proportionality coefficient in formula, for the frequency of sagging output, fgFor mains frequency, Δ θ is phase
Change.
Systematic parameter is as follows：Gird-connected inverter DC voltage 700V；Power grid phase voltage peak value is 311V；Droop control device
Rated active power is 2kW, rated reactive power 0；Load active power is verified for 3kW.Experimental result such as attached drawing 4~
Shown in 5.Fig. 4 is the phase difference and its change rate after frequency disturbance between inverter and power grid when being incorporated into the power networks, can be with from figure
Even if finding out that occurrence frequency disturbs during being incorporated into the power networks, isolated island erroneous judgement will not occur.Fig. 5 is PCC dot frequency offsets f-
Fg, | d Δs θ/dt |, isolated island detection signal graph, after as can be seen from the figure isolated island occurs, change rate signal is bigger and in steady
Definite value through can consider isolated island after a period of time.
Embodiment described above is only that the preferred embodiment of the present invention is described, not to the model of the present invention
Enclose and be defined, on the premise of design spirit of the present invention is not departed from, technical side of the those of ordinary skill in the art to the present invention
The various modifications and improvement that case is made, should all fall into the protection domain that claims of the present invention determines.
Claims (4)
1. a kind of island detection method of droop control gird-connected inverter, it is characterised in that the described method comprises the following steps：
Step 1, three-phase grid-connected inverter main circuit system is built；
Step 2, the active power of output and reactive power of three-phase grid-connected inverter are calculated；
Step 3, addition disturbance k (f-f are utilizedgThe improvement droop control device of)/s calculates the reference output of voltage magnitude and phase；Formula
Middle k is proportionality coefficient, and f is the frequency of sagging output, fgFor mains frequency, s is pull-type operator；
Step 4, reference voltage and phase are obtained into error voltage value with virtual voltage and phase as difference, as outer shroud adjuster
Reference input, the output of adjuster is the reference input of interior circular current, then obtains error current value as difference with actual current, as
The input of inner ring adjuster, the output finally obtained are modulated signal；
Step 5, monitoring in real time | d Δs θ/dt |=| k (f-fg) | value carry out isolated island judgement, k be proportionality coefficient in formula, and f is sagging
The frequency of output, fgFor mains frequency, Δ θ is phase place change.
A kind of 2. island detection method of droop control gird-connected inverter according to claim 1, it is characterised in that：Step
In 1, three-phase main circuit structure uses three-phase half-bridge structure and LC filter structures.
A kind of 3. island detection method of droop control gird-connected inverter according to claim 1, it is characterised in that：Step
In 3, the angle of traditional isolated island monitoring P-f droop control devices is exported
It is changed into
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<mi>&theta;</mi>
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<mo>=</mo>
<mfrac>
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<mn>2</mn>
<mi>&pi;</mi>
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Deformation obtains：
In formula, P exports actual active power for inverter, and P* is given active power, and m is sagging coefficient, and f* gives to be sagging
Fixed frequency, f'=f, f are sagging output frequency, fgFor the actual frequency of power grid, θ ' is the angle of sagging final output, k=2
π k', k is proportionality coefficient in formula, and s is pull-type operator.
A kind of 4. island detection method of droop control gird-connected inverter according to claim 1, it is characterised in that：Step
In 5, monitoring in real time | d Δs θ/dt |=| k (f-fg) | value, when its value is stationary value, as judge isolated island occur foundation.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201711389264.0A CN107947240A (en) | 2017-12-21 | 2017-12-21 | A kind of island detection method of droop control gird-connected inverter |
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| CN201711389264.0A CN107947240A (en) | 2017-12-21 | 2017-12-21 | A kind of island detection method of droop control gird-connected inverter |
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| CN107947240A true CN107947240A (en) | 2018-04-20 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113759184A (en) * | 2020-06-03 | 2021-12-07 | 台达电子企业管理（上海）有限公司 | Island detection method and device of inverter |
| US11936310B2 (en) | 2020-06-03 | 2024-03-19 | Delta Electronics (Shanghai) Co., Ltd | Control method and device for three-phase AC system |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103630782A (en) * | 2013-11-29 | 2014-03-12 | 江苏兆伏新能源有限公司 | Isolated island detection method and device for three-phase grid connected inverter |
| CN104135033A (en) * | 2014-08-25 | 2014-11-05 | 哈尔滨工业大学 | Voltage type control method for novel photovoltaic grid-connected inverter |
| CN105790307A (en) * | 2016-04-21 | 2016-07-20 | 许继集团有限公司 | Inverter control method and system based on droop control |
| CN106961121A (en) * | 2017-04-26 | 2017-07-18 | 西安交通大学 | Seamless switching control system and strategy based on current indirect control and droop control |
-
2017
- 2017-12-21 CN CN201711389264.0A patent/CN107947240A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103630782A (en) * | 2013-11-29 | 2014-03-12 | 江苏兆伏新能源有限公司 | Isolated island detection method and device for three-phase grid connected inverter |
| CN104135033A (en) * | 2014-08-25 | 2014-11-05 | 哈尔滨工业大学 | Voltage type control method for novel photovoltaic grid-connected inverter |
| CN105790307A (en) * | 2016-04-21 | 2016-07-20 | 许继集团有限公司 | Inverter control method and system based on droop control |
| CN106961121A (en) * | 2017-04-26 | 2017-07-18 | 西安交通大学 | Seamless switching control system and strategy based on current indirect control and droop control |
Non-Patent Citations (1)
| Title |
|---|
| 王琳: "基于下垂控制的并网逆变器的孤岛检测研究", 《中国优秀硕士学位论文全文数据库 工程科技II辑》 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113759184A (en) * | 2020-06-03 | 2021-12-07 | 台达电子企业管理（上海）有限公司 | Island detection method and device of inverter |
| US20210384735A1 (en) * | 2020-06-03 | 2021-12-09 | Delta Electronics (Shanghai) Co., Ltd | Islanding detection mothod for inverter and apparatus |
| US11777322B2 (en) * | 2020-06-03 | 2023-10-03 | Delta Electronics (Shanghai) Co., Ltd | Islanding detection mothod for inverter and apparatus |
| US11936310B2 (en) | 2020-06-03 | 2024-03-19 | Delta Electronics (Shanghai) Co., Ltd | Control method and device for three-phase AC system |
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Application publication date: 20180420 |