CN111366805B - Island detection method and device and photovoltaic grid-connected power generation system - Google Patents
Island detection method and device and photovoltaic grid-connected power generation system Download PDFInfo
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- CN111366805B CN111366805B CN202010228325.0A CN202010228325A CN111366805B CN 111366805 B CN111366805 B CN 111366805B CN 202010228325 A CN202010228325 A CN 202010228325A CN 111366805 B CN111366805 B CN 111366805B
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
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Abstract
The embodiment of the invention relates to the field of grid-connected photovoltaic power generation, and discloses a method for detecting an island, which is applied to a grid-connected photovoltaic power generation system connected with an external power grid and used for acquiring island detection parameters from a storage unit of the grid-connected photovoltaic power generation system; collecting electrical parameters of a photovoltaic grid-connected power generation system connected with the external power grid; carrying out island detection on the photovoltaic grid-connected power generation system according to the electrical parameters and the island detection parameters; if the grid-connected photovoltaic power generation system is in an island, recording the time length of the grid-connected photovoltaic power generation system in the island; acquiring electrical parameters of an external power grid when the time length of the photovoltaic grid-connected power generation system in an island is less than a preset threshold value within a preset time period; and adjusting the island detection parameters according to the acquired electrical parameters of the external power grid. Therefore, island detection parameters are automatically adjusted to adapt to different power grid environments, the detection accuracy can be improved, and the workload of power grid maintenance is reduced.
Description
Technical Field
The embodiment of the invention relates to the field of grid-connected photovoltaic power generation, in particular to a method and a device for detecting an island and a grid-connected photovoltaic power generation system.
Background
In photovoltaic grid-connected power generation, received solar radiation energy is converted into high-voltage direct current through a photovoltaic array after being converted into high-frequency direct current, and sinusoidal alternating current with the same frequency and phase as the voltage of a power grid is output to the power grid after being inverted by an inverter, so that solar energy is converted into electric energy, and the photovoltaic grid-connected power generation is more and more widely applied. However, the islanding effect is always a common problem in the grid-connected photovoltaic power generation system, and the islanding effect means that when the grid-connected photovoltaic power generation system interrupts power supply due to electrical faults, misoperation or natural factors, the grid-connected photovoltaic power generation system cannot detect the power failure state in time and cannot separate the grid-connected photovoltaic power generation system from the grid-connected photovoltaic power generation system and still supplies power to surrounding loads, so that a self-supply power supply islanding which cannot be controlled by a power company is formed, and damage is caused to a power grid and maintenance personnel. Therefore, the grid-connected photovoltaic power generation system needs to detect the islanding effect in time, and must stop grid-connected power generation and send out a warning, and this protective action is called islanding protection. The islanding protection is restricted by a plurality of objective conditions, such as power grid environments of weak power grids, multi-machine parallel connection and the like, so that the islanding misjudgment or missed judgment frequently occurs due to an over-sensitive detection threshold value, and the power generation amount and the user experience are influenced.
In the process of implementing the embodiment of the present invention, the inventor of the present invention finds that: currently, island detection mainly sets detection parameters, monitors electrical parameters corresponding to the detection parameters, such as frequency or frequency variation, and determines whether the electrical parameters are in an island state. The detection parameters cannot be adjusted reasonably according to local conditions, and the conditions that the detection parameters are unreasonable and the like are easy to occur, so that misjudgment or missed judgment is generated.
Disclosure of Invention
The embodiment of the invention mainly solves the technical problem of providing an island detection method, which can automatically adjust island detection parameters to adapt to different power grid environments, improve the detection accuracy and reduce the workload of power grid maintenance.
In order to solve the above technical problem, in a first aspect, an embodiment of the present invention provides a method for detecting an island, which is applied to a photovoltaic grid-connected power generation system connected to an external power grid, and includes:
obtaining island detection parameters from a storage unit of the photovoltaic grid-connected power generation system;
collecting electrical parameters of a photovoltaic grid-connected power generation system connected with the external power grid;
carrying out island detection on the photovoltaic grid-connected power generation system according to the electrical parameters and the island detection parameters;
if the grid-connected photovoltaic power generation system is in an island, recording the time length of the grid-connected photovoltaic power generation system in the island;
acquiring electrical parameters of the photovoltaic grid-connected power generation system when the time length of the photovoltaic grid-connected power generation system in an island is less than a preset threshold value within a preset time period;
and adjusting the island detection parameters according to the obtained electrical parameters of the photovoltaic grid-connected power generation system.
In some embodiments, the step of adjusting the island detection parameter according to the obtained electrical parameter of the grid-connected pv power generation system further includes:
and increasing the island detection parameters according to a preset step length.
In some embodiments, the step of adjusting the island detection parameter according to the obtained electrical parameter of the grid-connected photovoltaic power generation system further includes:
calculating a difference value between each obtained electrical parameter of the photovoltaic grid-connected power generation system and the island detection parameter;
calculating an average of the differences;
and taking the sum of the island detection parameter and the average value as a new island detection parameter of the photovoltaic grid-connected power generation system.
In some embodiments, the method further comprises:
and storing the adjusted island detection parameters into a storage unit of the photovoltaic grid-connected power generation system, and covering the original island detection parameters.
In some embodiments, the step of performing island detection on the grid-connected pv power generation system according to the electrical parameter and the island detection parameter further includes:
judging whether the electrical parameter is larger than an island detection parameter;
if so, determining that the photovoltaic grid-connected power generation system meets an island condition, and controlling the photovoltaic grid-connected power generation system to be disconnected from the external power grid;
if not, determining that the photovoltaic grid-connected power generation system does not meet the island condition, and controlling the photovoltaic grid-connected power generation system to be connected with the external power grid.
In some embodiments, the electrical parameter is frequency, frequency rate of change, voltage harmonics, voltage phase jump, or impedance.
In order to solve the above technical problem, in a second aspect, an embodiment of the present invention provides an apparatus for detecting an island, which is applied to a photovoltaic grid-connected power generation system connected to an external power grid, and includes:
the first acquisition module is used for acquiring island detection parameters from a storage unit of the photovoltaic grid-connected power generation system;
the acquisition module is used for acquiring the electrical parameters of the photovoltaic grid-connected power generation system connected with the external power grid;
the detection module is used for carrying out island detection on the photovoltaic grid-connected power generation system according to the electrical parameters and the island detection parameters;
the timing module is used for recording the time length of the photovoltaic grid-connected power generation system in an island if the photovoltaic grid-connected power generation system is in the island;
the second acquisition module is used for acquiring the electrical parameters of the photovoltaic grid-connected power generation system when the time length of the photovoltaic grid-connected power generation system in an island is less than a preset threshold value within a preset time period;
and the adjusting module is used for adjusting the island detection parameters according to the obtained electrical parameters of the photovoltaic grid-connected power generation system.
In some embodiments, the system further includes a storage module, configured to store the adjusted islanding detection parameter into a storage unit of the grid-connected photovoltaic power generation system, and cover an original islanding detection parameter.
In some embodiments, the adjusting module is specifically configured to: and increasing the island detection parameters according to a preset step length.
In order to solve the above technical problem, in a third aspect, an embodiment of the present invention provides a grid-connected photovoltaic power generation system, including:
a solar power panel;
the grid-connected inverter is used for being connected with the solar power generation panel and an external power grid;
at least one processor connected with the grid-connected inverter;
a memory communicatively coupled to the at least one processor; wherein the content of the first and second substances,
the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method of the first aspect as described above.
The embodiment of the invention has the following beneficial effects: different from the situation of the prior art, the island detection method provided by the embodiment of the invention is applied to a photovoltaic grid-connected power generation system connected with an external power grid, and island detection parameters are obtained from a storage unit of the photovoltaic grid-connected power generation system; collecting electrical parameters of a photovoltaic grid-connected power generation system connected with the external power grid; carrying out island detection on the photovoltaic grid-connected power generation system according to the electrical parameters and the island detection parameters; if the grid-connected photovoltaic power generation system is in an island, recording the time length of the grid-connected photovoltaic power generation system in the island; acquiring electrical parameters of an external power grid when the time length of the photovoltaic grid-connected power generation system in an island is less than a preset threshold value within a preset time period; and adjusting the island detection parameters according to the acquired electrical parameters of the external power grid. Therefore, island detection parameters are automatically adjusted to adapt to different power grid environments, the detection accuracy can be improved, and the workload of power grid maintenance is reduced.
Drawings
One or more embodiments are illustrated by way of example in the accompanying drawings, which correspond to the figures in which like reference numerals refer to similar elements and which are not to scale unless otherwise specified.
Fig. 1 is a schematic structural diagram of a photovoltaic grid-connected power generation system provided in an embodiment of the present invention;
fig. 2 is a flowchart of a method for detecting an islanding according to an embodiment of the present invention;
FIG. 3 is a sub-flow diagram of step 230 of the method of FIG. 2;
FIG. 4 is a sub-flow diagram of step 260 of the method of FIG. 2;
FIG. 5 is another sub-flow diagram of step 260 of the method of FIG. 2;
FIG. 6 is a flow chart of another method of detecting islanding provided in an embodiment of the present invention;
fig. 7 is a schematic structural diagram of an apparatus for detecting islanding provided in an embodiment of the present invention;
fig. 8 is a schematic structural diagram of a grid-connected photovoltaic power generation system according to an embodiment of the present invention.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
It should be noted that, if not conflicting, various features of the embodiments of the present invention may be combined with each other within the scope of protection of the present application. Additionally, while functional block divisions are performed in apparatus schematics, with logical sequences shown in flowcharts, in some cases, steps shown or described may be performed in sequences other than block divisions in apparatus or flowcharts. Further, the terms "first," "second," "third," and the like, as used herein, do not limit the data and the execution order, but merely distinguish the same items or similar items having substantially the same functions and actions.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Referring to fig. 1, a schematic structural diagram of a photovoltaic grid-connected power generation system 100 includes a photovoltaic cell panel array 10, an inverter 20, and a transformer 30 connected in sequence, where the transformer 30 is connected to an external power grid 50, and the photovoltaic cell panel array 10 includes a plurality of photovoltaic cell panels connected in parallel to convert solar energy into direct current electric energy. Then, the direct current generated by the photovoltaic cell panel array plate 10 is inverted into alternating current through the inverter 20, and the alternating current is boosted to 220V through the transformer 30 and then is connected to the external power grid 50, so that photovoltaic power generation is completed.
This grid-connected PV power generation system 100 still includes island detection module 40, island detection module 40 with inverter 20 is connected, can in time detect the emergence of island, is convenient for directly will grid-connected PV power generation system 100 with the separation of external electric wire netting 50 eliminates the island effect.
Specifically, please refer to fig. 2, which is a schematic flow chart of a method for detecting an island according to an embodiment of the present invention, applied to the island detection module 40, where the method includes:
step 210: and obtaining island detection parameters from a storage unit of the photovoltaic grid-connected power generation system.
The islanding detection parameter refers to a threshold corresponding to a detected detection object, where the detection object may be an electrical parameter representing current, such as frequency or voltage, and the islanding detection parameter is a corresponding frequency threshold or voltage threshold. It should be noted that the island detection parameter is set according to manual detection experience and is pre-stored in a storage unit of the grid-connected photovoltaic power generation system. The islanding detection parameter is typically influenced by the grid, i.e. different grid environments have respective islanding detection parameters.
Step 220: and collecting the electrical parameters of the photovoltaic grid-connected power generation system connected with the external power grid.
The electrical parameters are used for representing the electrical parameters of the current in the photovoltaic grid-connected power generation system and the change of the electrical parameters. In some embodiments, the electrical parameter may be the electrical parameter and its variation at the output of the inverter. It will be appreciated that in some embodiments, the electrical parameter is frequency, rate of change of frequency, voltage harmonics, voltage phase jump, or impedance.
Step 230: and carrying out island detection on the photovoltaic grid-connected power generation system according to the electrical parameters and the island detection parameters.
According to the electrical parameters and the island detection parameters, an active detection method can be adopted to perform island detection on the photovoltaic grid-connected power generation system, and the active detection method can include: an automatic frequency/phase shift method, a voltage/frequency positive feedback method, an output active disturbance method or an output reactive compensation method. It can be understood that, a passive detection method may also be used to perform island detection on the grid-connected pv power generation system, where the passive detection method may include: an output voltage/frequency detection method, a voltage harmonic detection method, a phase shift detection method, or a key electrical quantity change rate detection method. The above-listed active and passive detection methods are well established in the prior art, and are not described herein again.
In some embodiments, referring to fig. 3, the step 230 further includes:
step 231: and judging whether the electrical parameter is larger than the island detection parameter, if so, executing a step 232, and if not, executing a step 233.
And when the electrical parameter is larger than the island detection parameter, namely the electrical parameter exceeds a set critical detection value, determining that the photovoltaic grid-connected power generation system meets the island condition. And when the electrical parameter is less than or equal to the island detection parameter, namely the electrical parameter does not exceed a set critical detection value, determining that the photovoltaic grid-connected power generation system does not meet the island condition.
Step 232: and determining that the grid-connected photovoltaic power generation system meets an island condition, and controlling the grid-connected photovoltaic power generation system to be disconnected from the external power grid.
When the grid-connected photovoltaic power generation system meets the island condition, the grid-connected photovoltaic power generation system is controlled to be disconnected from the external power grid, and damage to electric equipment and power maintenance personnel is avoided.
Step 233: and determining that the photovoltaic grid-connected power generation system does not meet the island condition, and controlling the photovoltaic grid-connected power generation system to be connected with the external power grid.
And when the grid-connected photovoltaic power generation system does not meet the island condition, controlling the grid-connected photovoltaic power generation system to be connected with the external power grid, so that the grid-connected photovoltaic power generation system supplies power normally.
Step 240: and if the photovoltaic grid-connected power generation system generates an island, recording the time length of the photovoltaic grid-connected power generation system in the island.
The duration of the photovoltaic grid-connected power generation system in the island refers to the duration of the detected island. In some embodiments, the duration of the islanding of the grid-connected photovoltaic power generation system may be obtained by the state of the external power grid.
Specifically, when the photovoltaic grid-connected power generation system is detected to generate an island, timing is started, and whether the external power grid is in a normal state or not is detected. And when the external power grid is detected to be normal, stopping timing, and thus acquiring the time length of the photovoltaic grid-connected power generation system in an island.
Step 250: and acquiring the electrical parameters of the photovoltaic grid-connected power generation system when the time length of the photovoltaic grid-connected power generation system in an island is less than a preset threshold value within a preset time period.
The preset threshold is a time threshold and is set manually according to experience or multiple tests. The predetermined period of time is a period of time when islanding is detected, for example, within 3 minutes or within 5 minutes when islanding is detected.
When the time length of the photovoltaic grid-connected power generation system in the island is less than a preset threshold value within a preset time period, the fact that the photovoltaic grid-connected power generation system has the island is judged to be misjudged, namely if the time length of the photovoltaic grid-connected power generation system in the island is less than the preset threshold value, the fact that the island does not occur can be judged.
Therefore, when the time length of the photovoltaic grid-connected power generation system in an island is less than a preset threshold value within a preset time period, the electrical parameters of the photovoltaic grid-connected power generation system mean that when the island is misjudged (no island occurs), the electrical parameters of the photovoltaic grid-connected power generation system are detected, and the electrical parameters can be used for evaluating the rationality of the island detection parameters and guiding the determination of the island detection parameters.
Step 260: and adjusting the island detection parameters according to the obtained electrical parameters of the photovoltaic grid-connected power generation system.
Therefore, the electrical parameters of the photovoltaic grid-connected power generation system are obtained when the islanding is misjudged, and therefore the islanding parameters are unreasonable. And adjusting the island detection parameters according to the obtained electrical parameters of the photovoltaic grid-connected power generation system, and determining island detection parameters suitable for the photovoltaic grid-connected power generation system again.
In some embodiments, referring to fig. 4, the step 260 further includes:
step 261 a: and increasing the island detection parameters according to a preset step length.
The preset step length is the increment of the island detection parameter each time, and can be determined by historical detection experience or by algorithm fitting to determine the optimal preset step length so as to avoid that the step length is too large and the proper island detection parameter is missed, or the step length is too small and the proper island detection parameter can be determined in a long time.
In some embodiments, referring to fig. 5, the step 260 further includes:
step 261 b: and calculating the difference value between each obtained electrical parameter of the photovoltaic grid-connected power generation system and the island detection parameter.
Step 262 b: the average of the differences is calculated.
Step 263 b: and taking the sum of the island detection parameter and the average value as a new island detection parameter of the photovoltaic grid-connected power generation system.
And calculating difference values between the obtained electrical parameters of the photovoltaic grid-connected power generation system and the island detection parameters within a preset time period, then averaging the difference values, and taking the sum of the island detection parameters and the average value as a new island detection parameter of the photovoltaic grid-connected power generation system, thereby equivalently increasing an island detection threshold value, ensuring that island detection is stricter and the accuracy is higher.
To implement island detection parameter adaptation, automatic adjustment, in some embodiments, please refer to fig. 6, the method further includes:
step 270: and storing the adjusted island detection parameters into a storage unit of the photovoltaic grid-connected power generation system, and covering the original island detection parameters.
And storing the adjusted island detection parameter into a storage unit of the grid-connected photovoltaic power generation system, and covering the original island detection parameter, namely replacing the original island detection parameter with the adjusted island detection parameter to detect whether the grid-connected photovoltaic power generation system is isolated, so that the island detection parameter can be adaptively adjusted according to the external power grid environment to adapt to different external power grids.
In this embodiment, the island detection parameters are automatically adjusted by the above method to adapt to different power grid environments, so that the detection accuracy can be improved, and the workload of power grid maintenance is reduced.
An embodiment of the present invention further provides an islanding detection device, please refer to fig. 7, which shows a structure of the islanding detection device provided in the embodiment of the present application, where the device 300 is applied to a photovoltaic grid-connected power generation system connected to an external power grid, and includes: a first acquisition module 310, an acquisition module 320, a detection module 330, a timing module 340, a second acquisition module 350, and an adjustment module 360.
The first obtaining module 310 is configured to obtain an island detection parameter from a storage unit of the grid-connected photovoltaic power generation system. The collection module 320 is configured to collect electrical parameters of a photovoltaic grid-connected power generation system connected to the external power grid. The detection module 330 is configured to perform island detection on the photovoltaic grid-connected power generation system according to the electrical parameter and the island detection parameter. The timing module 340 is configured to record a duration of the isolated island of the photovoltaic grid-connected power generation system if the isolated island of the photovoltaic grid-connected power generation system occurs. The second obtaining module 350 is configured to obtain an electrical parameter of the photovoltaic grid-connected power generation system when a duration of the photovoltaic grid-connected power generation system being in an island within a predetermined time period is less than a preset threshold. The adjusting module 360 is configured to adjust the island detection parameter according to the obtained electrical parameter of the photovoltaic grid-connected power generation system.
In some embodiments, the adjusting module 360 is specifically configured to: and increasing the island detection parameters according to a preset step length.
In some embodiments, the adjusting module 360 is further specifically configured to calculate a difference between each obtained electrical parameter of the photovoltaic grid-connected power generation system and the island detection parameter; calculating an average of the differences; and taking the sum of the island detection parameter and the average value as a new island detection parameter of the photovoltaic grid-connected power generation system.
In some embodiments, the detection module 330 is specifically configured to determine whether the electrical parameter is greater than an island detection parameter; if yes, determining that the photovoltaic grid-connected power generation system meets an island condition, and controlling the photovoltaic grid-connected power generation system to be disconnected from the external power grid; if not, determining that the photovoltaic grid-connected power generation system does not meet the island condition, and controlling the photovoltaic grid-connected power generation system to be connected with the external power grid.
In some embodiments, the apparatus 300 further includes a storage module 370, configured to store the adjusted islanding detection parameter into a storage unit of the grid-connected pv power generation system, and override the original islanding detection parameter.
In this embodiment, the first obtaining module 310 obtains an island detection parameter from a storage unit of the grid-connected pv power generation system, the collecting module 320 collects an electrical parameter of the grid-connected pv power generation system connected to the external grid, and the detecting module 330 performs island detection on the grid-connected pv power generation system according to the electrical parameter and the island detection parameter; if the grid-connected photovoltaic power generation system is isolated, the timing module 340 records the time length of the grid-connected photovoltaic power generation system in the isolated island, and the second obtaining module 350 obtains the electrical parameters of the external power grid when the time length of the grid-connected photovoltaic power generation system in the isolated island is smaller than a preset threshold value in a preset time period. Finally, the adjusting module 360 adjusts the island detection parameter according to the obtained electrical parameter of the external power grid. Therefore, island detection parameters are automatically adjusted to adapt to different power grid environments, the detection accuracy can be improved, and the workload of power grid maintenance is reduced.
Referring to fig. 8, the embodiment of the present invention further provides a photovoltaic grid-connected power generation system 400, where the photovoltaic grid-connected power generation system 400 includes a solar power generation panel 410, a grid-connected inverter 420, at least one processor 430, and a memory 440. The grid-connected inverter 420 is used for connecting the solar panel 410 and an external power grid. And at least one processor 430 connected to the grid-connected inverter 420.
A memory 440 communicatively coupled to the at least one processor 430, the memory 440 storing instructions executable by the at least one processor 430, the instructions being executable by the at least one processor 430 to enable the at least one processor 430 to perform the method of detecting islanding as described above with reference to fig. 2-6. The processor 430 and the memory 440 may be connected by a bus or other means, and fig. 8 illustrates the connection by a bus as an example.
The memory 440, which is a non-volatile computer-readable storage medium, may be used to store non-volatile software programs, non-volatile computer-executable programs, and modules, such as program instructions/modules corresponding to the method for detecting islanding in the embodiment of the present application, for example, the modules shown in fig. 7. The processor 430 executes various functional applications and data processing of a method for detecting islanding by running nonvolatile software programs, instructions and modules stored in the memory 440, that is, implements a method for detecting islanding in the above method embodiment and functions of various modules in the above apparatus embodiment.
The memory 440 may include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area may store data created from use of a device for detecting islanding, and the like.
Further, memory 440 may include high speed random access memory, and may also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other non-volatile solid state storage device. In some embodiments, the memory optionally includes memory located remotely from the processor, and such remote memory may be coupled to the processor via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
The program instructions and one or more modules are stored in the memory 440, and when executed by the one or more processors 430, perform a method for detecting islanding in any of the above-described method embodiments, for example, the method steps of fig. 2 to 6 described above are performed to implement the functions of the modules in fig. 7.
The photovoltaic grid-connected power generation system 400 can execute the method provided by the embodiment of the application, and has the corresponding functional modules and beneficial effects of the execution method. For technical details that are not described in detail in this embodiment, reference may be made to the methods provided in the embodiments of the present application.
It should be noted that the above-described device embodiments are merely illustrative, where the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a general hardware platform, and certainly can also be implemented by hardware. It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware related to instructions of a computer program, which can be stored in a computer readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), or the like.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; within the idea of the invention, also technical features in the above embodiments or in different embodiments may be combined, steps may be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (8)
1. A method for detecting an island is applied to a photovoltaic grid-connected power generation system connected with an external power grid, and is characterized by comprising the following steps:
obtaining island detection parameters from a storage unit of the photovoltaic grid-connected power generation system;
collecting electrical parameters of a photovoltaic grid-connected power generation system connected with the external power grid;
carrying out island detection on the photovoltaic grid-connected power generation system according to the electrical parameters and the island detection parameters;
the island detection parameters are frequency thresholds or voltage thresholds corresponding to detected detection objects, and the island detection parameters are stored in a storage unit of the photovoltaic grid-connected power generation system in advance; if the grid-connected photovoltaic power generation system is in an island, recording the time length of the grid-connected photovoltaic power generation system in the island;
acquiring electrical parameters of the photovoltaic grid-connected power generation system when the time length of the photovoltaic grid-connected power generation system in an island is less than a preset threshold value within a preset time period;
adjusting the island detection parameters according to the obtained electrical parameters of the photovoltaic grid-connected power generation system;
adjusting the island detection parameter comprises:
increasing the island detection parameters according to a preset step length;
calculating a difference value between each obtained electrical parameter of the photovoltaic grid-connected power generation system and the island detection parameter;
calculating an average value of the difference values;
and taking the sum of the island detection parameter and the average value as a new island detection parameter of the photovoltaic grid-connected power generation system.
2. The method of claim 1, further comprising:
and storing the adjusted island detection parameters into a storage unit of the photovoltaic grid-connected power generation system, and covering the original island detection parameters.
3. The method according to any one of claims 1-2, wherein the step of performing island detection on the grid-connected photovoltaic power generation system according to the electrical parameter and the island detection parameter further comprises:
judging whether the electrical parameter is larger than an island detection parameter;
if yes, determining that the photovoltaic grid-connected power generation system meets an island condition, and controlling the photovoltaic grid-connected power generation system to be disconnected from the external power grid;
if not, determining that the photovoltaic grid-connected power generation system does not meet the island condition, and controlling the photovoltaic grid-connected power generation system to be connected with the external power grid.
4. The method according to any of claims 1-2, wherein the electrical parameter is frequency or voltage.
5. The utility model provides a detect device of isolated island, is applied to the grid-connected PV power generation system who is connected with external electric wire netting, its characterized in that includes:
the first acquisition module is used for acquiring island detection parameters from a storage unit of the photovoltaic grid-connected power generation system;
the acquisition module is used for acquiring the electrical parameters of the photovoltaic grid-connected power generation system connected with the external power grid;
the detection module is used for carrying out island detection on the photovoltaic grid-connected power generation system according to the electrical parameters and the island detection parameters;
the island detection parameters are frequency thresholds or voltage thresholds corresponding to detected detection objects, and the island detection parameters are stored in a storage unit of the photovoltaic grid-connected power generation system in advance; the timing module is used for recording the time length of the photovoltaic grid-connected power generation system in an island if the photovoltaic grid-connected power generation system is in the island;
the second acquisition module is used for acquiring the electrical parameters of the photovoltaic grid-connected power generation system when the time length of the photovoltaic grid-connected power generation system in an island is less than a preset threshold value within a preset time period;
the adjusting module is used for adjusting the island detection parameters according to the obtained electrical parameters of the photovoltaic grid-connected power generation system;
adjusting the island detection parameter comprises:
increasing the island detection parameters according to a preset step length;
calculating a difference value between each obtained electrical parameter of the photovoltaic grid-connected power generation system and the island detection parameter;
calculating an average of the differences;
and taking the sum of the island detection parameter and the average value as a new island detection parameter of the photovoltaic grid-connected power generation system.
6. The device of claim 5, further comprising a storage module, configured to store the adjusted islanding detection parameter into a storage unit of the grid-connected photovoltaic power generation system, and to override an original islanding detection parameter.
7. The apparatus of claim 5, wherein the adjustment module is specifically configured to: and increasing the island detection parameters according to a preset step length.
8. A grid-connected photovoltaic power generation system, comprising:
a solar power panel;
the grid-connected inverter is used for being connected with the solar power generation panel and an external power grid;
at least one processor connected with the grid-connected inverter;
a memory communicatively coupled to the at least one processor; wherein the content of the first and second substances,
the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method of any one of claims 1-4.
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