CN102590663B - Improved intermittent reactive power disturbance island detection method - Google Patents
Improved intermittent reactive power disturbance island detection method Download PDFInfo
- Publication number
- CN102590663B CN102590663B CN 201210023557 CN201210023557A CN102590663B CN 102590663 B CN102590663 B CN 102590663B CN 201210023557 CN201210023557 CN 201210023557 CN 201210023557 A CN201210023557 A CN 201210023557A CN 102590663 B CN102590663 B CN 102590663B
- Authority
- CN
- China
- Prior art keywords
- reactive power
- power disturbance
- frequency
- disturbance
- intermittent
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 238000001514 detection method Methods 0.000 title claims abstract description 58
- 238000000034 method Methods 0.000 claims abstract description 25
- 230000008878 coupling Effects 0.000 claims abstract description 20
- 238000010168 coupling process Methods 0.000 claims abstract description 20
- 238000005859 coupling reaction Methods 0.000 claims abstract description 20
- 238000005070 sampling Methods 0.000 claims description 7
- 230000011664 signaling Effects 0.000 claims description 6
- 238000012360 testing method Methods 0.000 claims description 6
- 230000000737 periodic effect Effects 0.000 abstract 2
- 238000004891 communication Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000010248 power generation Methods 0.000 description 4
- 230000002093 peripheral effect Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000005856 abnormality Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000009415 formwork Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
Images
Landscapes
- Supply And Distribution Of Alternating Current (AREA)
Abstract
The invention discloses an improved intermittent reactive power disturbance island detection method. The method applies periodic reactive power disturbance on an inverter controller, and each reactive power disturbance period is divided into reactive power disturbance time and non-reactive power disturbance time. At the starting time of each reactive power disturbance period, the voltage frequency detected by a frequency detection module is bestowed on a reactive power disturbance quantity calculating module, the minimum reactive power disturbance quantity required for the period is then calculated by the reactive power quantity calculating module, the reactive power disturbance quantity can ensure that the frequency of a common coupling point deviates out of an allowed range when an island phenomenon occurs, an intermittent reactive power disturbance signal module generates an intermittent reactive power disturbance signal of the period according to the calculated reactive power disturbance quantity, and periodic intermittent reactive power disturbance is applied on the inverter controller so as to achieve the purpose of detecting the island. According to the improved intermittent reactive power disturbance island detection method, the island phenomenon can be timely and effectively detected, the reactive power disturbance quantity required for the island detection can be reduced, and the influence on the grid-tied power factor is smaller.
Description
Technical field
The present invention relates to the isolated island detection technique in distributed generation system and combining inverter application, especially a kind of without improved intermittent reactive power disturbance island detection method.
Background technology
Day by day serious due to the quick consumption of the non-renewable energy resources such as fossil energy and environmental problem, the new forms of energy distributed power generation has been subject to paying close attention to widely gradually.In the new forms of energy distributed power generation, wind energy, photovoltaic, the electric energy that fuel cell etc. produce, be transformed into qualified electric energy through power converter and be connected to the grid.Combining inverter is as the interface between new forms of energy and electrical network, can be converted and carry out quality of power supply control electric energy.Usually distributed generation system comprises single-phase or three-phase grid-connected inverter, isolating switch, local load and public electric wire net.Combining inverter is connected with public electric wire net through isolating switch with local load, and tie point is point of common coupling (PCC).When external power grid breaks down and while disconnecting, combining inverter and local load break away from electrical network and form the local electric network composition with Blast Furnace Top Gas Recovery Turbine Unit (TRT), be referred to as isolated island.The reason that isolated island produces is a lot, mainly comprises that the circuit that electric network fault, isolating switch damage and disaster etc. cause destroys.The generation of isolated island is generally unpredictable, may bring distributed power generation device and local load because of voltage or the frequency damage caused out of control, even personal safety is formed to certain threat.So distributed generation system must adopt a kind of effective island detection method to detect the generation of isolated island.
Island detection method is divided into three classes usually: (1) passive island detection method; (2) active island detection method; (3) PERCOM peripheral communication island detection method.Usually weigh the validity of island detection method with non-detection zone (NDZ), what non-detection zone meaned is that specific island detection method can not detect the zone of island state under given local load characteristic condition.
Passive island detection method judges the generation of isolated island by the system electrical parameters such as voltage magnitude, frequency, phase place and harmonic wave that detect point of common coupling.Cross/under-voltage method (OVP/UVP), super/under-frequency method (OFP/UFP) is the most frequently used passive island detection method.Whether cross/under-voltage method exceeds by detecting the point of common coupling voltage magnitude generation that the line voltage allowed band is judged isolated island, and whether super/under-frequency method exceeds by detecting the point of common coupling electric voltage frequency generation that the mains frequency allowed band is judged isolated island.GB/T 19939-2005 (requirement of photovoltaic system interconnection technology) regulation mains frequency can not exceed the scope of 49.5Hz to 50.5Hz.Passive island detection method is realized simple, do not affect and network electric energy quality, but when inverter output is meritorious and when reactive power and load consumption meritorious and idle approaching, passive island detection method may lose efficacy, and fell into non-detection zone.
Active island detection method is, by combining inverter, point of common coupling is introduced to disturbance, and the electrical parameter (comprising voltage magnitude, frequency etc.) that impels isolated island that rear system occurs exceeds allowed band, thereby judges the generation of isolated island.Active island detection method comprises frequency departure method (AFD), sliding formwork frequency deviation method (SMS),
sandiafrequency deviation method, reactive power disturbance method (RPV) etc.Active island detection method reduces even to eliminate non-detection zone, simultaneously can to and network electric energy quality have a certain impact.Traditional intermittent reactive power disturbance method is to introduce just idle disturbance and the negative idle disturbance of constant basis within a disturbance cycle, can eliminate non-detection zone.But traditional reactive power disturbance method can be introduced larger disturbance quantity to the reactive power of combining inverter output, reduces the inverter output power factor, exists larger defect.
The PERCOM peripheral communication detection method is by between electrical network and distributed power generation device, setting up the generation that communication contact detects isolated island, but too high cost has limited the application of PERCOM peripheral communication detection method.
Summary of the invention
The present invention is directed to the deficiencies in the prior art, proposed a kind of fundamental purpose and be to propose a kind of improved intermittent reactive power disturbance island detection method.The method detects the point of common coupling electric voltage frequency by the initial time in the idle disturbance cycle, calculates the idle disturbance quantity of minimum of required introducing of this cycle, thereby successfully detects the generation of isolated island.
A kind of improved intermittent reactive power disturbance alone island detection system comprises isolated island test main circuit, frequency detection module, reactive power disturbance control loop, circuit control device and frequency determination module; Isolated island test main circuit comprises single-phase/three-phase combining inverter, RLC load, isolating switch and the electrical network for connecting electrical network based on the PWM modulation; Frequency detection module detects the point of common coupling electric voltage frequency for per sampling period; Circuit control device is for the reactive power amount of control inverter output appointment; The frequency determination module is for judging whether isolated island occurs; The intermittent reactive power disturbance control loop comprises reactive power disturbance amount computing module and intermittent reactive power disturbance signaling module.
The concrete detecting step of the method comprises:
Step 1, within each sampling period, frequency detection module detects the electric voltage frequency of point of common coupling;
When
fduring 50Hz, export idle disturbance quantity and be:
Wherein
pfor the inverter active power of output,
q f for the load quality factor,
f min the minimum value allowed for mains frequency,
f max the maximal value allowed for mains frequency;
Step 3, the intermittent reactive power disturbance signaling module is according to idle disturbance quantity
qgenerate the intermittent reactive power disturbance signal in this cycle, each reactive power disturbance cycle T is divided into idle disturbance time T
1with non-idle disturbance time T
2, in idle disturbance time T
1in, the idle disturbance quantity of output is fixed value
q,
qfor reactive power disturbance amount computing module calculates the idle disturbance quantity of gained, non-idle disturbance time T according to this disturbance cycle initial time electric voltage frequency
2the idle disturbance quantity of interior output is zero;
Simultaneously, the frequency values that frequency detection module records, the frequency values by the frequency determination module to point of common coupling voltage is judged, if frequency is greater than 50.5Hz or is less than 49.5Hz, assert now electrical network and combining inverter disengagement, and isolated island occurs.
Beneficial effect: the island detection method simple possible that the present invention proposes, compare traditional reactive power disturbance island detection method, only need in software, increase a reactive power disturbance control loop, before exporting idle disturbance in per cycle, the point of common coupling electric voltage frequency obtained according to frequency detection module calculates the reactive power disturbance amount in this cycle, and the idle disturbance quantity of gained is when isolated island, to impel the point of common coupling electric voltage frequency to be offset out the minimum value of frequency allowed band.Thereby with traditional intermittent two-sided reactive power disturbance method, compare, per cycle only need to be introduced monolateral idle disturbance, and idle disturbance quantity can be reduced.Finally make grid-connected system obtain higher grid-connected power factor and effective isolated island detectability, the present invention is applicable to the new forms of energy distributed generation systems such as sun power, wind-force, fuel cell, the generation that detects combining inverter isolated island phenomenon that can be successful, meet the isolated island detection time that GB requires, and less on the impact of grid-connected power factor.
The accompanying drawing explanation
The improved intermittence of Fig. 1 is idle, and the disturbance alone island detection system forms schematic diagram;
The improved intermittent reactive power disturbance method of Fig. 2 output reactive power sequential chart;
The improved intermittence of Fig. 3 is idle disturbance island detection method implementing procedure figure.
Embodiment
Below in conjunction with accompanying drawing, the technical solution of the present invention is further elaborated.
As shown in Figure 1, a kind of improved intermittent reactive power disturbance alone island detection system comprises isolated island test main circuit, frequency detection module 5, reactive power disturbance control loop, circuit control device 8 and frequency determination module 9; Isolated island test main circuit comprise based on the PWM modulation single-phase or three-phase grid-connected inverter 1, RLC load 2, isolating switch 3 and the public electric wire net 4 for connecting electrical network; Frequency detection module 5 detects the point of common coupling electric voltage frequency for per sampling period; Circuit control device 8 is for the reactive power amount of control inverter output appointment; Frequency determination module 9 is for judging whether isolated island occurs; Intermittent reactive power disturbance control loop reactive power disturbance amount computing module 6 and intermittent reactive power disturbance signaling module 7.
The concrete detecting step of the method comprises:
Step 1, within each sampling period, the electric voltage frequency of point of common coupling is measured in frequency detection module inspection 5;
When
fduring 50Hz, export idle disturbance quantity and be:
Wherein
pfor the inverter active power of output,
q f for the load quality factor,
f min the minimum value allowed for mains frequency,
f max the maximal value allowed for mains frequency;
Step 3, intermittent reactive power disturbance signaling module 7 is according to idle disturbance quantity
qgenerate the intermittent reactive power disturbance signal in this cycle, each reactive power disturbance cycle T is divided into idle disturbance time T
1with non-idle disturbance time T
2, in idle disturbance time T
1in, the idle disturbance quantity of output is fixed value
q,
qfor reactive power disturbance amount computing module 6 calculates the idle disturbance quantity of gained, non-idle disturbance time T according to this disturbance cycle initial time electric voltage frequency
2the idle disturbance quantity of interior output is zero;
Simultaneously, the frequency values that frequency detection module records, judged by the frequency values of 9 pairs of point of common coupling voltages of frequency determination module, if frequency is greater than 50.5Hz or is less than 49.5Hz, and continue 1 power frequency period, assert now electrical network and combining inverter disengagement, isolated island occurs.
The inventive method is exported idle sequential with reference to Fig. 2, and principle is as follows:
The combining inverter output reactive power is periodically variable, and each reactive power disturbance cycle T is divided into idle disturbance time T
1with non-idle disturbance time T
2, in idle disturbance time T
1in, the idle disturbance quantity of output is fixed value
q, non-idle disturbance time T
2the idle disturbance quantity of interior output is zero.As shown in Figure 2, can obtain the inverter output reactive power
expression formula be:
Consider that isolated island can not be greater than 2s detection time, set the disturbance cycle
, the idle disturbance time
, the quiescent interval
.Above embodiment only, for explanation technological thought of the present invention, can not limit protection scope of the present invention with this, every according to design procedure of the present invention, and any modification that time parameter and idle parameter are made, within all falling into protection domain of the present invention.
As shown in Figure 3, principle is as follows for the inventive method workflow diagram:
Each sampling period enters interrupt routine, and frequency detection module detects the frequency of point of common coupling voltage, by the frequency determination module, carries out the island state judgement.Concrete decision method is: frequency detection module obtains the frequency of point of common coupling voltage; if this frequency is greater than 50.5Hz or is less than 49.5Hz; think the electrical network abnormal; if in continuous 1 power frequency period, mains frequency is always in abnormality; assert that isolated island occurs, the island protect module is closed inverter.If now mains frequency does not exceed allowed band, the circuit control device normal operation.In process flow diagram, counter is the power frequency period counter, and initial value is 0, and every 20ms, count value adds 1.The cycle T that can make intermittent idle disturbance is 2s, and when counter count down to 100 cycles, set is 0 again, exports idle disturbance time T
1be decided to be 200ms, counter is 0 to 9 o'clock, export idle disturbance, and counter is at 10 to 99 o'clock, does not export idle disturbance.The idle disturbance quantity of the intermittent reactive power disturbance method that the present invention proposes is relevant with PCC dot frequency before idle disturbance, therefore, when counter is 0, now the PCC dot frequency is obtained and is assigned to
f, according to
fsize can calculate the idle disturbance quantity of required minimum of this cycle with different formula
q, when counter is 0 to 9, exports idle disturbance quantity and be
q, when counter is 10 to 99, exporting idle disturbance quantity is 0, when counter count down to 100 cycles, set is 0 again.By the process flow diagram shown in Fig. 3, can obtain reactive power output timing as shown in Figure 2, and effectively detect the generation of isolated island.
Claims (1)
1. an improved intermittent reactive power disturbance island detection method, improved intermittent reactive power disturbance alone island detection system comprises isolated island test main circuit, frequency detection module, reactive power disturbance control loop, circuit control device and frequency determination module; Isolated island test main circuit comprises single-phase or three-phase grid-connected inverter, RLC load, isolating switch and the public electric wire net for connecting electrical network based on the PWM modulation; Frequency detection module detects the point of common coupling electric voltage frequency for per sampling period; Circuit control device is for the reactive power amount of control inverter output appointment; The frequency determination module is for judging whether isolated island occurs; The reactive power disturbance control loop comprises reactive power disturbance amount computing module and intermittent reactive power disturbance signaling module, it is characterized in that the concrete detecting step of the method comprises:
Step 1, within each sampling period, frequency detection module detects the electric voltage frequency of point of common coupling;
Step 2, initial time in each reactive power disturbance cycle T, the reactive power disturbance amount computing module basis frequency values f that now frequency detection module provides, calculate the reactive power disturbance amount Q that in the reactive power disturbance time in this cycle, inverter should be exported, when f≤50Hz, this cycle output reactive power disturbance quantity is:
As f > during 50Hz, the output reactive power disturbance quantity is:
The active power that wherein P is inverter output, Q
ffor load quality factor, f
minfor the minimum value that mains frequency allows, f
maxthe maximal value allowed for mains frequency;
Step 3, the intermittent reactive power disturbance signaling module generates the intermittent reactive power disturbance signal in this cycle according to reactive power disturbance amount Q, and each reactive power disturbance cycle T is divided into the reactive power disturbance time T
1with non-reactive power disturbance time T
2, in the reactive power disturbance time T
1in, the reactive power disturbance amount of output is fixed value Q, Q is that reactive power disturbance amount computing module calculates the reactive power disturbance amount of gained, non-reactive power disturbance time T according to this disturbance cycle initial time electric voltage frequency
2the reactive power disturbance amount of interior output is zero;
Step 4, circuit control device sends intermittent reactive power according to the intermittent reactive power disturbance signal controlling inverter generated; Frequency detection module records frequency values, frequency values by the frequency determination module to point of common coupling voltage is judged, if frequency is greater than 50.5Hz or is less than 49.5Hz, and continues 1 power frequency period, assert now electrical network and combining inverter disengagement, isolated island occurs.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201210023557 CN102590663B (en) | 2012-02-02 | 2012-02-02 | Improved intermittent reactive power disturbance island detection method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201210023557 CN102590663B (en) | 2012-02-02 | 2012-02-02 | Improved intermittent reactive power disturbance island detection method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN102590663A CN102590663A (en) | 2012-07-18 |
| CN102590663B true CN102590663B (en) | 2013-12-25 |
Family
ID=46479584
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201210023557 Expired - Fee Related CN102590663B (en) | 2012-02-02 | 2012-02-02 | Improved intermittent reactive power disturbance island detection method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN102590663B (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102830312B (en) * | 2012-08-29 | 2014-11-05 | 江苏兆伏新能源有限公司 | Islanding detection method of grid-connected inverter |
| CN102841279B (en) * | 2012-08-31 | 2014-10-15 | 天津大学 | Micro-grid island detection method |
| EP2720338B1 (en) * | 2012-10-10 | 2021-06-09 | FIMER S.p.A. | Method and arrangement for detecting an islanding operation of a distributed power generator |
| CN103257298B (en) * | 2013-05-14 | 2015-08-26 | 合肥工业大学 | Based on the combining inverter island detection method of parameter adaptive Sandia frequency deviation method |
| CN103645416B (en) * | 2013-08-30 | 2015-08-19 | 天津大学 | A kind of microgrid non-destructive island detection method based on self-adaptation reactive disturbance |
| US9520819B2 (en) | 2014-02-28 | 2016-12-13 | General Electric Company | System and method for controlling a power generation system based on a detected islanding event |
| CN103941118B (en) * | 2014-03-26 | 2017-01-04 | 中国科学院电工研究所 | Island detection method for photovoltaic power generation grid-connected inverter group system |
| CN106019010B (en) * | 2016-05-23 | 2018-09-25 | 南昌大学 | A kind of mixing isolated island detection method combined based on synovial membrane frequency deviation method and passive means |
| CN112782501B (en) * | 2020-12-02 | 2022-10-25 | 合肥工业大学 | Parameter-adaptive improved active frequency shift type island detection method |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101268218A (en) * | 2005-09-19 | 2008-09-17 | Abb瑞士有限公司 | Method for detecting islanding operation of a distributed generator |
| CN102156233A (en) * | 2011-03-21 | 2011-08-17 | 浙江大学 | Method for detecting island by intermittent two-sided reactive power disturbance |
| CN102170141A (en) * | 2009-11-13 | 2011-08-31 | 伊顿公司 | Method and area electric power system detecting islanding by employing controlled reactive power injection by a number of inverters |
| CN102208817A (en) * | 2011-05-13 | 2011-10-05 | 中国电子科技集团公司第三十六研究所 | Reactive-power-disturbance-based grid-connected island detection method for photovoltaic system |
| CN102290802A (en) * | 2011-08-22 | 2011-12-21 | 哈尔滨工业大学 | Island detection method of AFD (active frequency drift) based on synchronous rotation coordinate system |
-
2012
- 2012-02-02 CN CN 201210023557 patent/CN102590663B/en not_active Expired - Fee Related
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101268218A (en) * | 2005-09-19 | 2008-09-17 | Abb瑞士有限公司 | Method for detecting islanding operation of a distributed generator |
| CN102170141A (en) * | 2009-11-13 | 2011-08-31 | 伊顿公司 | Method and area electric power system detecting islanding by employing controlled reactive power injection by a number of inverters |
| CN102156233A (en) * | 2011-03-21 | 2011-08-17 | 浙江大学 | Method for detecting island by intermittent two-sided reactive power disturbance |
| CN102208817A (en) * | 2011-05-13 | 2011-10-05 | 中国电子科技集团公司第三十六研究所 | Reactive-power-disturbance-based grid-connected island detection method for photovoltaic system |
| CN102290802A (en) * | 2011-08-22 | 2011-12-21 | 哈尔滨工业大学 | Island detection method of AFD (active frequency drift) based on synchronous rotation coordinate system |
Non-Patent Citations (5)
| Title |
|---|
| 刘文华等.三相光伏发电系统瞬时电流控制及其孤岛检测技术.《清华大学学报（自然科学版）》.2011,第51卷(第3期),第345-350页. * |
| 基于间歇性双边无功率扰动的三相并网逆变器孤岛检测研究;张俊;《中国优秀硕士学位论文全文数据库》;20110731(第7期);第28-43页 * |
| 张俊.基于间歇性双边无功率扰动的三相并网逆变器孤岛检测研究.《中国优秀硕士学位论文全文数据库》.2011,(第7期),第28-43页. |
| 张俊等.间歇性双边无功功率扰动孤岛检测策略.《电源学报》.2011,(第2期),第7-10页. |
| 间歇性双边无功功率扰动孤岛检测策略;张俊等;《电源学报》;20110331(第2期);第7-10页 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN102590663A (en) | 2012-07-18 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102590663B (en) | Improved intermittent reactive power disturbance island detection method | |
| CN101257209B (en) | Islet operation detecting method of photovoltaic parallel network generating system | |
| CN102156233A (en) | Method for detecting island by intermittent two-sided reactive power disturbance | |
| CN101123349B (en) | Island effect detection method based on active frequency deviation and its device | |
| CN102183733B (en) | Photovoltaic grid connected inverter island detection method for improving quality of electric energy | |
| CN103412207B (en) | Based on the method for detecting island of photovoltaic grid-connected inverter that negative-sequence current injects | |
| CN102262182B (en) | Method for detecting island of photovoltaic grid-connected inverter | |
| CN102208817A (en) | Reactive-power-disturbance-based grid-connected island detection method for photovoltaic system | |
| CN102843060B (en) | Two-level two-direction current transformer and control method thereof | |
| CN102611183B (en) | Method for detecting and protecting isolated island of grid-connected power generation system | |
| CN101794988B (en) | Method for detecting piconet island state | |
| CN103760434A (en) | Self-adaption phase deviation island detection method based on fuzzy control | |
| CN102437587A (en) | Island detection method of high-power photovoltaic grid-connected converter | |
| CN105870953A (en) | Light storage combined grid-connected system and control method thereof | |
| CN109510230A (en) | A kind of continuous commutation failure suppressing method for HVDC transmission system | |
| CN202004458U (en) | Active filter circuit with intelligent communication function | |
| CN103185846B (en) | A kind of countercurrent detection method, Countercurrent prevention control method, device and countercurrent prevention system | |
| CN102170142A (en) | Low-voltage ride-through method for photovoltaic inverter | |
| CN101938140B (en) | Distributed power supply system | |
| CN102377195B (en) | Isolated operation detection device | |
| JP2014117016A (en) | Single operation detection device and method, power conditioner and distributed power source system | |
| CN105182189A (en) | Inverter disturbance type island detection method based on combination of voltage frequency and measured impedance | |
| CN102879672A (en) | Bidirectional active power disturbance island detection method | |
| CN103091604A (en) | Island detection method and detection device for grid-connected photovoltaic power generation system | |
| CN202870202U (en) | Islanding detection system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20131225 |
|
| CF01 | Termination of patent right due to non-payment of annual fee |