CN115021676A - Photovoltaic system direct current arc fault detection method, device, equipment and medium - Google Patents
Photovoltaic system direct current arc fault detection method, device, equipment and medium Download PDFInfo
- Publication number
- CN115021676A CN115021676A CN202210614970.5A CN202210614970A CN115021676A CN 115021676 A CN115021676 A CN 115021676A CN 202210614970 A CN202210614970 A CN 202210614970A CN 115021676 A CN115021676 A CN 115021676A
- Authority
- CN
- China
- Prior art keywords
- arc
- signal
- arc fault
- photovoltaic system
- direct current
- 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.)
- Pending
Links
- 238000001514 detection method Methods 0.000 title claims abstract description 191
- 238000004891 communication Methods 0.000 claims abstract description 138
- 238000000034 method Methods 0.000 claims abstract description 61
- 230000035945 sensitivity Effects 0.000 claims description 25
- 238000000605 extraction Methods 0.000 claims description 24
- 238000005457 optimization Methods 0.000 claims description 4
- 230000006870 function Effects 0.000 description 9
- 238000010586 diagram Methods 0.000 description 8
- 230000003044 adaptive effect Effects 0.000 description 7
- 230000005856 abnormality Effects 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- 238000004364 calculation method Methods 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000010891 electric arc Methods 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000004069 differentiation Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
- H02S50/00—Monitoring or testing of PV systems, e.g. load balancing or fault identification
-
- 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
- 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
- G01R31/1227—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 of components, parts or materials
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
Abstract
The invention discloses a method, a device and equipment for detecting a direct current arc fault of a photovoltaic system and a computer readable storage medium, wherein the method comprises the steps of acquiring a direct current side alternating current signal of an inverter in the photovoltaic system; extracting signal characteristics of a preset arc detection frequency band in the direct current side alternating current signal as first arc signal characteristics, and extracting signal characteristics of a preset communication frequency band in the direct current side alternating current signal as first communication signal characteristics; and when the suspicious direct current arc fault is judged to occur based on the first arc signal characteristic and the power optimizer in the photovoltaic system is judged not to be communicated based on the first communication signal characteristic, determining that the real direct current arc fault occurs in the photovoltaic system. The direct-current arc fault detection scheme of the invention realizes that when the power optimizer and the arc detection function are compatible, the influence of the communication of the power optimizer on the arc detection is avoided, and the false detection rate of the arc detection is reduced.
Description
Technical Field
The invention relates to the technical field of photovoltaic power stations, in particular to a method, a device and equipment for detecting a direct current arc fault of a photovoltaic system and a computer readable storage medium.
Background
The arc is a gas discharge phenomenon, and once an arc fault occurs in a photovoltaic system, if effective measures are not taken for protection, a fire disaster is easily caused by high temperature generated by continuous direct current arc, so that a major safety accident is caused. In the existing arc detection technology, the occurrence of a direct current arc fault is detected by extracting a direct current side signal to detect and identify arc frequency domain characteristics. In a photovoltaic system, in order to solve the power mismatch phenomenon caused by partial shadow shielding, component aging and the like of a photovoltaic component, a power optimizer needs to be connected in series to adjust the power output of each photovoltaic panel, so that the power generation efficiency of the series is improved. The optimizer control device needs to perform information interaction with each secondary node Power optimizer through Power Line Communication (PLC).
Because the power optimizer needs to couple the high-frequency harmonic signal through the cable, and the frequency domain characteristics of the arc detection are mainly extracted from the cable-coupled harmonic signal, the power optimizer inevitably affects the arc detection when communicating, so that the arc detection is mistaken.
Disclosure of Invention
The invention mainly aims to provide a method, a device and equipment for detecting a direct current arc fault of a photovoltaic system and a computer readable storage medium, and aims to solve the technical problem that arc detection errors are caused by communication of a power optimizer when the power optimizer and an arc detection function are compatible in the photovoltaic system.
In order to achieve the above object, the present invention provides a method for detecting a dc arc fault of a photovoltaic system, which comprises the following steps:
acquiring a direct-current side alternating-current signal of an inverter in the photovoltaic system;
extracting a signal characteristic of a preset arc detection frequency band in the direct current side alternating current signal as a first arc signal characteristic, and extracting a signal characteristic of a preset communication frequency band in the direct current side alternating current signal as a first communication signal characteristic;
and when the suspicious direct current arc fault is judged to occur based on the first arc signal characteristic and the power optimizer in the photovoltaic system is judged not to be in communication based on the first communication signal characteristic, determining that the real direct current arc fault occurs in the photovoltaic system.
Optionally, after the step of extracting the signal feature of the preset arc detection frequency band in the direct-current-side alternating-current signal as the first arc signal feature, the method further includes:
acquiring a preset historical data set;
calculating to obtain an arc fault judgment threshold value based on each second arc signal characteristic in the historical data set;
and comparing the first arc signal characteristic with the arc fault determination threshold, and determining whether a suspicious direct current arc fault occurs or not based on the comparison result.
Optionally, after the step of extracting the signal feature of the preset arc detection frequency band in the dc-side ac signal as the first arc signal feature and extracting the signal feature of the preset communication frequency band in the dc-side ac signal as the first communication signal feature, the method further includes:
adding the first arc signature to the historical data set when it is determined that a power optimizer in the photovoltaic system is not communicating based on the first communication signature.
Optionally, the step of calculating an arc fault determination threshold based on each second arc signal feature in the historical data set includes:
and calculating the mean value of the characteristics of each second arc signal in the historical data set, and multiplying the mean value by a preset multiple to obtain the arc fault judgment threshold value.
Optionally, the photovoltaic system includes a plurality of power optimizers, and one of the power optimizers is used to perform power optimization on at least one photovoltaic module in the photovoltaic system;
after the step of determining that the photovoltaic system has a real dc arc fault, the method further includes:
respectively obtaining component voltages of corresponding photovoltaic components from the power optimizers;
acquiring a voltage abnormity detection threshold value;
and if the voltage of the photovoltaic module is smaller than the voltage abnormity detection threshold value, determining that the photovoltaic module is the photovoltaic module with the direct current arc fault.
Optionally, after the step of extracting the signal feature of the preset arc detection frequency band in the dc-side ac signal as the first arc signal feature and extracting the signal feature of the preset communication frequency band in the dc-side ac signal as the first communication signal feature, the method further includes:
and when the suspicious direct current arc fault is judged not to occur based on the first arc signal characteristic or the power optimizer in the photovoltaic system is judged to be in communication based on the first communication signal characteristic, returning to execute the step of acquiring the direct current side alternating current signal of the inverter in the photovoltaic system.
Optionally, the step of extracting a signal feature of a preset arc detection frequency band in the direct-current-side alternating-current signal as a first arc signal feature includes:
converting the time domain to the frequency domain of the alternating current signal at the direct current side to obtain a frequency domain signal;
and performing feature extraction on a signal of a preset arc detection frequency band in the frequency domain signal to obtain a first arc signal feature, wherein the feature extraction at least comprises one or more items of a mean value, a root mean square value, a variance and a kurtosis of the signal in the preset arc detection frequency band.
Optionally, after the step of extracting the signal feature of the preset arc detection frequency band in the direct-current-side alternating-current signal as the first arc signal feature, the method further includes:
acquiring a currently set arc fault detection sensitivity value;
selecting an arc fault judgment threshold value corresponding to the currently set arc fault detection sensitivity value from arc fault judgment threshold values corresponding to various preset sensitivity values as a target threshold value;
and comparing the first arc signal characteristic with the target threshold value, and judging whether a suspicious direct current arc fault occurs or not based on the comparison result.
Optionally, after the step of determining that a real dc arc fault occurs in the photovoltaic system when it is determined that a suspected dc arc fault occurs based on the first arc signal characteristic and it is determined that a power optimizer in the photovoltaic system is not in communication based on the first communication signal characteristic, the method further includes:
controlling the inverter to perform fault shutdown so as to report an arc fault;
and when a preset self-starting condition is met and the continuous time of the fault shutdown of the inverter reaches a preset time, controlling the inverter to be started, and executing the step of acquiring the direct-current side alternating current signal of the inverter in the photovoltaic system.
In order to achieve the above object, the present invention further provides a dc arc fault detection device for a photovoltaic system, including:
the acquisition module is used for acquiring a direct-current side alternating-current signal of an inverter in the photovoltaic system;
the extraction module is used for extracting a signal characteristic of a preset arc detection frequency band in the direct current side alternating current signal as a first arc signal characteristic and extracting a signal characteristic of a preset communication frequency band in the direct current side alternating current signal as a first communication signal characteristic;
and the determining module is used for determining that the photovoltaic system has a real direct current arc fault when the suspicious direct current arc fault is determined to occur based on the first arc signal characteristic and the power optimizer in the photovoltaic system is determined not to be in communication based on the first communication signal characteristic.
In order to achieve the above object, the present invention further provides a photovoltaic system dc arc fault detection device, including: the detection system comprises a memory, a processor and a photovoltaic system direct current arc fault detection program which is stored on the memory and can run on the processor, wherein the photovoltaic system direct current arc fault detection program realizes the steps of the photovoltaic system direct current arc fault detection method when being executed by the processor.
In addition, to achieve the above object, the present invention further provides a computer readable storage medium, where a photovoltaic system dc arc fault detection program is stored, and when being executed by a processor, the photovoltaic system dc arc fault detection program implements the steps of the photovoltaic system dc arc fault detection method described above.
According to the method, a direct current side alternating current signal of an inverter in a photovoltaic system is obtained; extracting signal characteristics of a preset arc detection frequency band in the direct current side alternating current signal as first arc signal characteristics, and extracting signal characteristics of a preset communication frequency band in the direct current side alternating current signal as first communication signal characteristics; and when the suspicious direct current arc fault is judged to occur based on the first arc signal characteristic and the power optimizer in the photovoltaic system is judged not to be communicated based on the first communication signal characteristic, determining that the real direct current arc fault occurs in the photovoltaic system. The direct-current arc fault detection scheme of the invention realizes that when the power optimizer and the arc detection function are compatible, the influence of the communication of the power optimizer on the arc detection is avoided, and the false detection rate of the arc detection is reduced.
Drawings
FIG. 1 is a schematic diagram of a hardware operating environment according to an embodiment of the present invention;
FIG. 2 is a schematic flow chart of a first embodiment of the photovoltaic system DC arc fault detection method of the present invention;
fig. 3 is a schematic diagram of a photovoltaic system architecture according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a DC arc fault detection process according to an embodiment of the present invention;
fig. 5 is a functional block diagram of a photovoltaic system dc arc fault detection apparatus according to a preferred embodiment of the present invention.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
As shown in fig. 1, fig. 1 is a schematic device structure diagram of a hardware operating environment according to an embodiment of the present invention.
It should be noted that, in the embodiment of the present invention, the dc arc fault detection device of the photovoltaic system may be a device such as a smart phone, a personal computer, or a server, and is not limited specifically here.
As shown in fig. 1, the photovoltaic system dc arc fault detection apparatus may include: a processor 1001, such as a CPU, a network interface 1004, a user interface 1003, a memory 1005, a communication bus 1002. Wherein a communication bus 1002 is used to enable connective communication between these components. The user interface 1003 may include a Display (Display), an input unit such as a Keyboard (Keyboard), and the optional user interface 1003 may also include a standard wired interface, a wireless interface. The network interface 1004 may optionally include a standard wired interface, a wireless interface (e.g., WI-FI interface). The memory 1005 may be a high-speed RAM memory or a non-volatile memory such as a disk memory. The memory 1005 may alternatively be a storage device separate from the processor 1001.
Those skilled in the art will appreciate that the device configuration shown in fig. 1 does not constitute a limitation of a photovoltaic system dc arc fault detection device and may include more or fewer components than shown, or some components in combination, or a different arrangement of components.
As shown in fig. 1, the memory 1005, which is a type of computer storage medium, may include an operating system, a network communication module, a user interface module, and a photovoltaic system dc arc fault detection program. The operating system is a program that manages and controls the hardware and software resources of the device, supporting the operation of the photovoltaic system dc arc fault detection program as well as other software or programs. In the device shown in fig. 1, the user interface 1003 is mainly used for data communication with a client; the network interface 1004 is mainly used for establishing communication connection with a server; and the processor 1001 may be configured to invoke the photovoltaic system dc arc fault detection program stored in the memory 1005 and perform the following operations:
acquiring a direct-current side alternating-current signal of an inverter in the photovoltaic system;
extracting a signal characteristic of a preset arc detection frequency band in the direct current side alternating current signal as a first arc signal characteristic, and extracting a signal characteristic of a preset communication frequency band in the direct current side alternating current signal as a first communication signal characteristic;
and when the suspicious direct current arc fault is judged to occur based on the first arc signal characteristic and the power optimizer in the photovoltaic system is judged not to be in communication based on the first communication signal characteristic, determining that the real direct current arc fault occurs in the photovoltaic system.
Further, after the operation of extracting the signal feature of the preset arc detection frequency band in the dc-side ac signal as the first arc signal feature, the processor 1001 may be further configured to call a photovoltaic system dc arc fault detection program stored in the memory 1005, and perform the following operations:
acquiring a preset historical data set;
calculating to obtain an arc fault judgment threshold value based on each second arc signal characteristic in the historical data set;
and comparing the first arc signal characteristic with the arc fault determination threshold, and determining whether a suspicious direct current arc fault occurs or not based on the comparison result.
Further, after the operation of extracting the signal feature of the preset arc detection frequency band in the dc-side ac signal as the first arc signal feature and extracting the signal feature of the preset communication frequency band in the dc-side ac signal as the first communication signal feature, the processor 1001 may be further configured to call a dc arc fault detection program of the photovoltaic system stored in the memory 1005, and execute the following operations:
adding the first arc signature to the historical data set when it is determined that a power optimizer in the photovoltaic system is not communicating based on the first communication signature.
Further, the operation of calculating an arc fault determination threshold based on each second arc signal characteristic in the historical data set includes:
and calculating the mean value of the characteristics of each second arc signal in the historical data set, and multiplying the mean value by a preset multiple to obtain the arc fault judgment threshold value.
Further, the photovoltaic system comprises a plurality of power optimizers, and one power optimizer is used for performing power optimization on at least one photovoltaic module in the photovoltaic system;
after the operation of determining that a real dc arc fault occurs in the photovoltaic system, the processor 1001 may be further configured to call a photovoltaic system dc arc fault detection program stored in the memory 1005, and perform the following operations:
respectively obtaining component voltages of corresponding photovoltaic components from the power optimizers;
acquiring a voltage abnormity detection threshold value;
and if the voltage of the photovoltaic module is smaller than the voltage abnormity detection threshold value, determining that the photovoltaic module is the photovoltaic module with the direct current arc fault.
Further, after the operation of extracting the signal feature of the preset arc detection frequency band in the dc-side ac signal as the first arc signal feature and extracting the signal feature of the preset communication frequency band in the dc-side ac signal as the first communication signal feature, the processor 1001 may be further configured to call a dc arc fault detection program of the photovoltaic system stored in the memory 1005, and execute the following operations:
and when the suspicious direct current arc fault is judged not to occur based on the first arc signal characteristic or the power optimizer in the photovoltaic system is judged to be in communication based on the first communication signal characteristic, returning to execute the operation of acquiring the direct current side alternating current signal of the inverter in the photovoltaic system.
Further, the operation of extracting the signal characteristic of the preset arc detection frequency band in the direct current side alternating current signal as the first arc signal characteristic includes:
converting the time domain to the frequency domain of the alternating current signal at the direct current side to obtain a frequency domain signal;
and performing feature extraction on a signal of a preset arc detection frequency band in the frequency domain signal to obtain a first arc signal feature, wherein the feature extraction at least comprises one or more items of a mean value, a root mean square value, a variance and a kurtosis of the signal in the preset arc detection frequency band.
Further, after the operation of extracting the signal feature of the preset arc detection frequency band in the dc-side ac signal as the first arc signal feature, the processor 1001 may be further configured to call a photovoltaic system dc arc fault detection program stored in the memory 1005, and execute the following operations:
acquiring a currently set arc fault detection sensitivity value;
selecting an arc fault judgment threshold value corresponding to the currently set arc fault detection sensitivity value from arc fault judgment threshold values corresponding to various preset sensitivity values as a target threshold value;
and comparing the first arc signal characteristic with the target threshold value, and judging whether a suspicious direct current arc fault occurs or not based on the comparison result.
Further, after determining that the photovoltaic system has an actual dc arc fault when it is determined that a suspected dc arc fault occurs based on the first arc signal characteristic and it is determined that the power optimizer in the photovoltaic system is not communicating based on the first communication signal characteristic, the processor 1001 may be further configured to call a photovoltaic system dc arc fault detection program stored in the memory 1005 to perform the following operations:
controlling the inverter to perform fault shutdown so as to report an arc fault;
and when a preset self-starting condition is met and the continuous time of the fault shutdown of the inverter reaches a preset time, controlling the inverter to be started, and executing the operation of acquiring the direct-current side alternating-current signal of the inverter in the photovoltaic system.
Based on the structure, various embodiments of the photovoltaic system direct current arc fault detection method are provided.
Referring to fig. 2, fig. 2 is a schematic flow chart of a photovoltaic system dc arc fault detection method according to a first embodiment of the present invention.
While a logical order is shown in the flow chart, in some cases, the steps shown or described may be performed in a different order than that shown or described herein. In this embodiment, an implementation subject of the method for detecting a dc arc fault in a photovoltaic system is not limited in this embodiment, and for convenience of description, the arc detection device is taken as the implementation subject to be described in the following embodiments. In this embodiment, the method for detecting a dc arc fault in a photovoltaic system includes:
step S10, acquiring a direct current side alternating current signal of an inverter in the photovoltaic system;
the direct current side of an inverter in the photovoltaic system is connected with a photovoltaic string, and the alternating current side of the inverter is connected with a power grid and a load, and is used for converting direct current output by one end of the photovoltaic string into alternating current and outputting the alternating current to the power grid and/or the load. The optimizer control device is a device for controlling the power optimizer, and is connected in series with or located in the inverter (hereinafter, the optimizer control device is located in the inverter as an example). The power optimizer optimizes the power of at least one photovoltaic module, and the power optimizer and the optimized photovoltaic module thereof can be regarded as a whole (the specific connection mode thereof is not limited in this embodiment); the photovoltaic modules are sequentially connected in series through the positive electrode and the negative electrode of the power optimizer to form a photovoltaic string, the positive electrode and the negative electrode of the photovoltaic string are connected with the positive electrode and the negative electrode of the direct current side of the inverter, when a plurality of photovoltaic strings exist, the photovoltaic strings are respectively connected with the inverter, and therefore the photovoltaic strings belong to a parallel connection relation. During the operation of the photovoltaic system, the optimizer control device communicates with the power optimizer periodically or aperiodically, and the communication frequency between the optimizer control device and the power optimizer is not limited in this embodiment. As shown in fig. 3, an architecture diagram of a photovoltaic system is shown, but the diagram is only a schematic diagram, and should not be construed as imposing any limitation on the architecture, function and use range of the photovoltaic system in the present embodiment.
When direct current arc fault detection is needed, the arc detection device acquires direct current side alternating current signals of an inverter in a photovoltaic system. Since some ac signals are also included in the dc-side current signal, the acquired dc-side current signal is referred to as a dc-side ac signal.
Step S20, extracting signal characteristics of a preset arc detection frequency band in the direct current side alternating current signal as first arc signal characteristics, and extracting signal characteristics of a preset communication frequency band in the direct current side alternating current signal as first communication signal characteristics;
after acquiring the dc-side ac signal, the arc detection apparatus may extract a signal feature of a preset arc detection frequency band in the dc-side ac signal, where the preset arc detection frequency band is a preset frequency band that is considered as a frequency band in which the arc signal feature is located, and thus the extracted signal feature is referred to as an arc signal feature (hereinafter, referred to as a first arc signal feature for distinction).
The arc detection device may further extract a signal characteristic of a preset communication frequency band in the dc-side ac signal, where the preset communication frequency band is a frequency band used by the optimizer control device to communicate with the power optimizer, and the extracted signal characteristic is referred to as a communication signal characteristic (hereinafter, referred to as a first communication signal characteristic for distinction) according to different devices and communication methods, where the preset communication frequency band may be different.
The method for extracting the first arc signal feature and the first communication signal feature is not limited in this embodiment, and a common frequency domain signal feature extraction method may be specifically adopted.
It should be noted that there may or may not be an overlap between the preset arc detection frequency band and the preset communication frequency band, in the case of the overlap, the communication between the optimizer control device and the power optimizer must have an influence on the arc detection, and in the case of the non-overlap, the closer the preset arc detection frequency band is to the preset communication frequency band, the greater the influence on the arc detection when the optimizer control device communicates with the power optimizer is.
Step S30, when it is determined that a suspected direct current arc fault occurs based on the first arc signal characteristics and it is determined that a power optimizer in the photovoltaic system is not in communication based on the first communication signal characteristics, it is determined that a real direct current arc fault occurs in the photovoltaic system.
After extracting the first arc signature, the arc detection device may determine whether a suspected dc arc fault exists based on the first arc signature. It should be noted that, since the result of detecting the dc arc fault based on the arc signal characteristics is affected when the optimizer control device communicates with the power optimizer, even if it is determined that the dc arc fault exists according to the first arc signal characteristics, the result is not necessarily accurate, and determining whether the dc arc fault exists according to the first arc signal characteristics is referred to as determining whether a suspected dc arc fault exists according to the first arc signal characteristics.
The specific method for determining whether there is a suspected dc arc fault according to the first arc signal characteristic is not limited in this embodiment, and for example, the comparison with a preset fixed threshold or the comparison with an adaptive threshold may be adopted, and whether there is a suspected dc arc fault is determined according to the comparison result.
After extracting the first communication signal characteristic, the arc detection device may determine whether the power optimizer is communicating according to the first communication signal characteristic, and it is understood that communicating with the power optimizer is communicating with the optimizer control device. The specific method for determining whether the power optimizer is performing communication according to the first communication signal characteristic is not limited in this embodiment, and for example, the specific method may be performed by comparing with a preset fixed threshold or comparing with an adaptive threshold, and determining whether the power optimizer is performing communication according to the comparison result.
When the suspected direct current arc fault is judged to occur based on the first arc signal characteristic and the power optimizer is judged not to be communicated based on the first communication signal characteristic, it can be determined that the direct current arc fault is not influenced by the communication between the optimizer control device and the power optimizer at the moment, the direct current arc fault is judged to be credible based on the first arc signal characteristic, namely, the arc detection device can determine that the real direct current arc fault occurs in the photovoltaic system.
Further, in an embodiment, after determining that a real dc arc fault occurs in the photovoltaic system, the arc detection apparatus may take corresponding measures to avoid an influence caused by the dc arc fault. The specific measures taken are not limited in this embodiment, and for example, the alarm device may be controlled to give an alarm.
Further, in an embodiment, the arc detection device may determine whether a suspicious dc arc fault occurs based on the first arc signal characteristic, and if it is determined that the suspicious dc arc fault occurs, may determine whether the power optimizer is performing communication based on the first communication signal characteristic, and if it is determined that the suspicious dc arc fault does not occur, may not perform detection on whether the power optimizer is performing communication, that is, it may be determined that the photovoltaic system does not generate a real dc arc fault. Or, in another embodiment, when it is only necessary to detect whether a real dc fault occurs, the arc detection apparatus may determine whether the power optimizer is performing communication based on the first communication signal characteristic, determine whether a suspected dc arc fault occurs based on the first arc signal characteristic if it is determined that the power optimizer is not performing communication, and determine whether the suspected dc arc fault occurs no longer if it is determined that the power optimizer is performing communication.
Further, in an embodiment, when it is determined that a suspected dc arc fault occurs based on the first arc signal characteristic and it is determined that the power optimizer is performing communication based on the first communication signal characteristic, the arc detection device may determine that the photovoltaic system has the suspected dc arc fault, that is, for a technician, it is likely that the photovoltaic system has the dc arc fault. Then, when it is determined that a suspected dc arc fault occurs, the arc detection apparatus may also set corresponding countermeasures as needed, and the countermeasures may be set to be different from or lower in level than the countermeasures for the true dc arc fault as needed. For example, the arc detection device may output an alarm prompt when it is determined that a suspected dc arc fault has occurred, and may directly control the inverter to stop when it is determined that a real dc arc fault has occurred, so as to block damage caused by the arc fault.
Further, in an embodiment, after the step S20, the method further includes:
step a, when it is determined that no suspected direct current arc fault occurs based on the first arc signal characteristic, or it is determined that a power optimizer in the photovoltaic system is performing communication based on the first communication signal characteristic, returning to perform the step S10.
When it is determined that no suspicious direct current arc fault occurs based on the first arc signal characteristic or it is determined that the power optimizer is performing communication based on the first communication signal characteristic, it cannot be determined that a real direct current arc fault occurs in the photovoltaic system, and in order to avoid false detection (it is determined that a real direct current arc fault occurs but actually does not occur), the arc detection device may directly return to perform the operation of acquiring the direct current side alternating current signal to perform arc signal characteristic extraction and communication signal characteristic extraction without performing corresponding countermeasures as required. It can be understood that the communication time between the power optimizer and the optimizer control device is generally short, and when it is determined that a suspected dc arc fault occurs based on the first arc signal characteristic and it is determined that the power optimizer is performing communication based on the first communication signal characteristic, although corresponding countermeasures are not performed, the next communication gap will come immediately, so if a dc arc fault actually occurs, the next communication gap can also be detected, and further adverse effects caused by the dc arc fault are avoided.
Further, in an embodiment, the step of extracting, in step S20, a signal characteristic of a preset arc detection frequency band in the dc-side ac signal as a first arc signal characteristic includes:
step S201, performing time domain to frequency domain conversion on the direct current side alternating current signal to obtain a frequency domain signal;
in the present embodiment, a method for extracting a first arc signal characteristic in a dc-side ac signal is provided. Specifically, the arc detection device may first perform time-domain to frequency-domain conversion on the dc-side ac signal to obtain a frequency-domain signal. It can be understood that the acquired direct current side alternating current signal is a signal composed of current values at different moments, belongs to a signal in a time domain, and in order to perform feature extraction on a signal in a preset arc detection frequency band in the signal, the direct current side alternating current signal may be converted from the time domain to a frequency domain, and the converted signal is referred to as a frequency domain signal. The method for converting the signal from the time domain to the frequency domain is not limited in this embodiment, and for example, a fast fourier transform method may be used.
Step S202, performing feature extraction on a signal of a preset arc detection frequency band in the frequency domain signal to obtain a first arc signal feature, wherein the feature extraction at least comprises one or more items of a mean value, a root mean square value, a variance and a kurtosis of the signal in the preset arc detection frequency band.
After the frequency domain signal is obtained through conversion, a signal in a preset arc detection frequency band can be extracted from the frequency domain signal, and the first arc signal characteristic is obtained through characteristic extraction of the part of the signal. According to specific needs, the feature extraction at least includes calculating one or more of a mean value, a root mean square value, a variance, and a kurtosis of the signal in the preset arc detection frequency band, and the method for calculating the mean value, the root mean square value, the variance, and the kurtosis is not described herein. It is understood that in other embodiments, feature extraction may also include other feature extraction methods.
Further, in an embodiment, the method for extracting the first communication signal feature in the dc-side ac signal may also be to convert the signal from a time domain to a frequency domain, extract a signal in a preset communication detection frequency band from the frequency domain signal, and perform feature extraction on the part of the signal to obtain the first communication signal feature, where the feature extraction at least may include calculating one or more of a mean value, a root mean square value, a variance, and a kurtosis for the signal in the preset arc detection frequency band.
In the embodiment, a direct current side alternating current signal of an inverter in a photovoltaic system is obtained; extracting signal characteristics of a preset arc detection frequency band in the direct current side alternating current signal as first arc signal characteristics, and extracting signal characteristics of a preset communication frequency band in the direct current side alternating current signal as first communication signal characteristics; and when the suspicious direct current arc fault is judged to occur based on the first arc signal characteristic and the power optimizer in the photovoltaic system is judged not to be communicated based on the first communication signal characteristic, determining that the real direct current arc fault occurs in the photovoltaic system. According to the direct-current arc fault detection scheme in the embodiment, when the power optimizer and the arc detection function are compatible, the influence of the communication of the power optimizer on the arc detection is avoided, and the false detection rate of the arc detection is reduced.
Further, based on the first embodiment, a second embodiment of the dc arc fault detection method for the photovoltaic system according to the present invention is provided. In this embodiment, after the step of extracting the signal characteristic of the preset arc detection frequency band in the dc-side ac signal as the first arc signal characteristic in step S20, the method further includes:
step S40, acquiring a preset historical data set;
in the embodiment, a method for detecting whether a suspected dc arc fault occurs based on an adaptive threshold is provided, where the adaptive threshold is a threshold adaptively determined according to a historical situation for comparing with a first arc signal characteristic, so as to improve an accuracy rate of arc detection. Specifically, a historical data set may be employed to store arc signal characteristics, hereinafter referred to as second arc signal characteristics, extracted based on the dc side ac signal over a historical period of time to distinguish them from the first arc signal characteristics. In this embodiment, how long the historical data is stored in the set for the arc signal characteristic is not limited, and may be specifically set according to needs.
Step S50, calculating to obtain an arc fault judgment threshold value based on each second arc signal characteristic in the historical data set;
when it is required to determine whether a suspected dc arc fault occurs based on the first arc signal characteristics, the arc detection apparatus may calculate an arc fault determination threshold, which is a threshold determined adaptively, based on each second arc signal characteristic in the historical data set.
The method for calculating the arc fault determination threshold according to each second arc signal characteristic is not limited in this embodiment, and for example, each second arc signal characteristic may be averaged or weighted and averaged, and may be specifically set as needed. When the second arc signal feature includes a plurality of feature values, for example, four types of feature values including a mean value, a root mean square value, a variance, and a kurtosis, the arc detection apparatus may calculate based on the same type of feature value in each second arc signal feature to obtain an arc fault determination threshold corresponding to the type of feature value, and then may finally obtain arc fault determination thresholds corresponding to the various types of feature values respectively.
Step S60, comparing the first arc signature with the arc fault determination threshold, and determining whether a suspected dc arc fault occurs based on the comparison result.
After the arc fault determination threshold is obtained, the arc detection device may compare the first arc signal characteristic with the arc fault determination threshold to obtain a comparison result, and may determine whether a suspected dc arc fault occurs according to the comparison result. The comparison result reflects a magnitude relationship between the first arc signal characteristic and the arc fault determination threshold, and when there is any comparison result, it may be determined that the occurrence of the suspected dc arc fault is settable according to needs. In a specific embodiment, when the first arc signal characteristic includes a plurality of types of characteristic values, each type of characteristic value may be compared with a corresponding type of arc fault determination threshold, respectively.
Further, in an embodiment, after the step S20, the method further includes:
step S70, when it is determined that the power optimizer in the photovoltaic system is not communicating based on the first communication signal characteristic, adding the first arc signal characteristic to the historical data set.
In order to avoid that the arc signal characteristics extracted based on the direct current side alternating current signals interfered by communication are added into the historical data set to influence the calculation accuracy of the adaptive threshold and further influence the accuracy of the arc fault detection, in the embodiment, the arc detection device may add the first arc signal characteristics into the historical data set when it is determined that the power optimizer in the photovoltaic system is not in communication based on the first communication signal characteristics.
Further, in an embodiment, the step S50 includes:
step S501, calculating the mean value of the characteristics of each second arc signal in the historical data set, and multiplying the mean value by a preset multiple to obtain the arc fault judgment threshold value.
In this embodiment, a method for calculating an arc fault determination threshold is provided, and specifically, the arc detection apparatus may calculate an average value of each second arc signal characteristic in the historical data set, and then multiply the average value by a preset multiple to obtain the arc fault determination threshold. When the first arc signal characteristic is smaller than the arc fault determination threshold value, and a suspicious direct current arc fault is determined to occur, the preset multiple is generally set to be larger than 0 and smaller than 1, so that the situation that the first arc signal characteristic is smaller than the arc fault determination threshold value to cause false detection due to the fact that the direct current arc fault does not occur in practice but only small fluctuation occurs in the direct current side alternating current signal is avoided.
Further, based on the first and/or second embodiments, a third embodiment of the method for detecting a dc arc fault in a photovoltaic system according to the present invention is provided. In this embodiment, the photovoltaic system includes a plurality of power optimizers, one power optimizer is used to optimize power of at least one photovoltaic module in the photovoltaic system, and after step S30, the method further includes:
step A10, respectively obtaining component voltages of corresponding photovoltaic components from each power optimizer;
in this embodiment, the power optimizer is used to obtain the voltage of the photovoltaic module optimized by the power optimizer (hereinafter referred to as module voltage) for locating the photovoltaic module in which the dc arc fault occurs.
Specifically, the power optimizer may detect the optimized photovoltaic module component voltage, and by means of communication between the power optimizer and the optimizer control device, the power optimizer may send the optimized photovoltaic module component voltage to the optimizer control device, and the arc detection device may obtain the photovoltaic module component voltage from the optimizer control device.
Step A20, obtaining a voltage anomaly detection threshold;
step A30, if the component voltage of the photovoltaic component is smaller than the voltage anomaly detection threshold value, determining that the photovoltaic component is a photovoltaic component with a direct current arc fault.
When a direct current arc fault occurs to the photovoltaic module, and partial cells of the photovoltaic module are damaged, the voltage of the photovoltaic module is reduced to a corresponding degree, the voltage abnormity detection threshold value is a threshold value used for judging whether the photovoltaic module has the direct current arc fault, and when the voltage of the photovoltaic module is smaller than the voltage abnormity detection threshold value, the photovoltaic module can be determined to have the direct current arc fault. The voltage abnormality detection threshold may be a fixed threshold set in advance according to needs, or may be determined adaptively, and is not limited in this embodiment.
In the embodiment, after the occurrence of the real direct current arc fault is determined, the component voltage of the photovoltaic component is obtained from the power optimizer, and the photovoltaic component with the direct current arc fault is positioned according to the comparison between the component voltage and the voltage abnormity detection threshold, so that a technician can clearly know the position of the photovoltaic component with the direct current arc fault, and then maintenance and management are performed, and the efficiency of removing the direct current arc fault is improved.
Further, in an embodiment, a method for obtaining a voltage anomaly detection threshold is provided. Specifically, the average value of the acquired module voltages of the photovoltaic modules may be calculated, and the average value is multiplied by a preset multiple (hereinafter referred to as a first preset multiple to indicate differentiation), so as to obtain the voltage anomaly detection threshold. The first preset multiple is greater than 0 and less than 1, specific values can be set according to needs, the larger the setting is, the lower the missed detection rate is, but the false detection situation may occur, and the lower the setting is, the lower the false detection rate is, but the missed detection situation may occur.
It should be noted that, when no dc arc fault occurs, the component voltages of the photovoltaic components are almost the same, and when a dc arc fault occurs in a photovoltaic component, the component voltages will be lower than the average level of the component voltages of the photovoltaic components, so that whether the dc arc fault occurs in the photovoltaic component can be detected by multiplying the average value of the component voltages of the photovoltaic components by a first preset multiple to serve as a voltage abnormality detection threshold, and then comparing the component voltage of the photovoltaic component with the voltage abnormality detection threshold.
Further, in an embodiment, another method for acquiring a voltage anomaly detection threshold is provided. Specifically, the arc detection device may obtain, in advance, a component voltage (hereinafter referred to as a historical component voltage) of each photovoltaic component when the photovoltaic system has no dc arc fault, and for each photovoltaic component, use the historical component voltage of the photovoltaic component when the photovoltaic component has no dc arc fault as a voltage abnormality detection threshold corresponding to the photovoltaic component. And comparing the acquired component voltage of the photovoltaic component with the voltage abnormity detection threshold value corresponding to the photovoltaic component, and if the acquired component voltage is smaller than the voltage abnormity detection threshold value, determining that the photovoltaic component has a direct current arc fault by the arc detection device. It can be understood that, when no dc arc fault occurs, when a dc arc fault occurs in a photovoltaic module, the module voltage will be lower than the voltage level when no dc arc fault occurs, so that whether a dc arc fault occurs in the photovoltaic module can be detected by using the module voltage when no dc arc fault occurs in the photovoltaic module as a voltage abnormality detection threshold and comparing the module voltage of the photovoltaic module with the voltage abnormality detection threshold.
Further, in an embodiment, after the step of extracting, in step S20, a signal characteristic of a preset arc detection frequency band in the dc-side ac signal as a first arc signal characteristic, the method further includes:
step A40, acquiring a currently set arc fault detection sensitivity value;
in the present embodiment, whether or not a dc arc fault occurs can be determined by comparing the first arc signal characteristic with a fixed threshold value set in advance, but in order to improve the flexibility of detection, arc fault determination threshold values corresponding to different sensitivities may be set in advance so as to meet the sensitivity requirements of different users for arc detection.
The arc detection device may acquire the currently set arc fault detection sensitivity. The arc detection device can be provided with a way for a user to input the arc fault detection sensitivity, and the user can set the arc detection sensitivity according to the requirement. Higher sensitivity indicates a lower false positive rate, but may cause false positives, while lower sensitivity indicates a lower false positive rate, but may cause false negatives.
Step A50, selecting an arc fault judgment threshold value corresponding to the currently set arc fault detection sensitivity value as a target threshold value from arc fault judgment threshold values corresponding to various preset sensitivity values;
the arc detection device selects an arc fault determination threshold corresponding to the currently set arc fault detection sensitivity value from among arc fault determination thresholds corresponding to preset various sensitivity values, as a threshold for comparison with the currently extracted first arc signal characteristic, and is hereinafter referred to as a target threshold for distinction. In one embodiment, when it is determined that a suspected dc arc fault has occurred when the first arc signal characteristic is set to be less than the arc fault determination threshold, the lower the sensitivity value, the higher the corresponding arc fault determination threshold may be set.
Step A60, comparing the first arc signature with the target threshold, and determining whether a suspected DC arc fault occurs based on the comparison result.
After determining the target threshold, the arc detection device may compare the first arc signature to the target threshold and determine whether a suspected dc arc fault has occurred based on the comparison. The comparison result reflects a magnitude relationship between the first arc signal characteristic and the electrical target threshold, and when there is any comparison result, it may be determined that the suspected dc arc fault occurs, which may be set as required. In a specific embodiment, when the first arc signal characteristic includes a plurality of types of characteristic values, each type of characteristic value may be compared with a corresponding type of target threshold value.
Further, in an embodiment, after the step S30, the method further includes:
step A70, controlling the inverter to be in fault shutdown so as to report an arc fault;
in the present embodiment, a countermeasure is provided when it is determined that a real dc arc fault occurs in the photovoltaic system. Specifically, after the real direct current arc fault is determined to occur, the arc detection device can control the inverter to stop due to the fault, and the arc fault is reported in a fault stop manner. In a specific embodiment, the inverter fault shutdown may specifically refer to a function of stopping a part of the function of converting direct current into alternating current, and other functions may continue to be operated.
Step A80, when the preset self-starting condition is met and the fault shutdown duration of the inverter reaches the preset duration, controlling the inverter to be started, and executing the step of acquiring the direct current side alternating current signal of the inverter in the photovoltaic system.
Further, in an embodiment, after the inverter is in the fault shutdown state, the arc detection device may time a fault shutdown duration of the inverter when a preset self-starting condition is satisfied, and may control the inverter to start when the preset duration is reached. After the inverter is controlled to be started, the arc detection device continues to acquire direct-current side alternating-current signals of the photovoltaic system inverter and continues to perform direct-current arc fault detection. The preset self-starting condition may be set as required, for example, the user may set that self-starting is possible, or the self-starting may not be possible after the inverter is shutdown for N times in one day, the self-starting may be performed within N times, and N may be set as required, for example, 5 times.
Further, in one embodiment, the flow of the dc arc fault detection may be as shown in fig. 4.
Firstly, after the inverter is powered on, parameter initialization is carried out, and an arc detection frequency band [ F1-F2 ] and an optimizer communication frequency band [ F1-F2 ] are preset;
secondly, in the grid-connected operation process, the arc detection device collects the direct current side alternating current signals of the inverter in real time and carries out Fast Fourier Transform (FFT) analysis;
thirdly, extracting arc signal characteristics (represented by arc characteristics in figure 4) of frequency bands [ F1-F2 ], including but not limited to at least one signal characteristic of mean value, root mean square value, variance, kurtosis and the like; extracting communication signal characteristics (represented by communication characteristics in fig. 4) of frequency bands [ f 1-f 2], including but not limited to at least one signal characteristic of mean value, root mean square value, variance, kurtosis and the like;
fourthly, comparing the characteristics of the arc signals with a preset threshold or a self-adaptive threshold, and judging whether an arc occurs; if the electric arc occurs, executing the fifth step; if no electric arc occurs, executing the second step;
fifthly, comparing the communication signal characteristics with a preset threshold or a self-adaptive threshold, and judging whether the PLC communication is carried out; if the optimizer is carrying out PLC communication, executing the second step; if the optimizer does not carry out communication, executing the sixth step;
and sixthly, stopping the inverter in a fault mode, and reporting an arc fault.
When the adaptive threshold is adopted, the threshold is obtained by multiplying the average value of historical data (represented by historical characteristic data in fig. 4) by a preset multiple, and because the optimizer can generate great influence on a communication frequency band and nearby frequency points when carrying out PLC communication, wide-range frequency domain signal change is caused, the arc signal characteristics and the communication signal characteristics obtained during the PLC communication can be not counted in the historical data, so that the adaptive threshold change caused by the PLC communication can be eliminated.
This embodiment combines power optimizer and arc detection function, through increase optimizer PLC communication frequency channel in arc detection device to whether discernment optimizer is carrying out the communication, has eliminated the interference of PLC communication to arc detection, realizes the compatibility of two functions. The problem of false alarm influence of PLC communication on arc detection of the optimizer is solved, self-adaptive threshold change caused by PLC communication is eliminated, the arc identification capability is improved, and efficient, safe and stable operation of a power station system is guaranteed.
In addition, an embodiment of the present invention further provides a photovoltaic system dc arc fault detection apparatus, and referring to fig. 5, the photovoltaic system dc arc fault detection apparatus includes:
the acquisition module 10 is configured to acquire a dc side ac signal of an inverter in the photovoltaic system;
an extraction module 20, configured to extract a signal feature of a preset arc detection frequency band in the dc-side ac signal as a first arc signal feature, and extract a signal feature of a preset communication frequency band in the dc-side ac signal as a first communication signal feature;
and the determining module 30 is configured to determine that a real dc arc fault occurs in the photovoltaic system when it is determined that a suspected dc arc fault occurs based on the first arc signal characteristic and it is determined that a power optimizer in the photovoltaic system does not perform communication based on the first communication signal characteristic.
Further, the obtaining module 10 is further configured to obtain a preset historical data set;
the photovoltaic system direct current arc fault detection device still includes:
the calculation module is used for calculating to obtain an arc fault judgment threshold value based on each second arc signal characteristic in the historical data set;
and the first comparison module is used for comparing the first arc signal characteristic with the arc fault judgment threshold value and judging whether a suspicious direct current arc fault occurs or not based on the comparison result.
Further, the photovoltaic system direct current arc fault detection device further includes:
an adding module for adding the first arc signature to the historical data set when it is determined that a power optimizer in the photovoltaic system is not communicating based on the first communication signature.
Further, the calculation module is further configured to:
and calculating the mean value of the characteristics of each second arc signal in the historical data set, and multiplying the mean value by a preset multiple to obtain the arc fault judgment threshold value.
Further, the photovoltaic system comprises a plurality of power optimizers, and one power optimizer is used for performing power optimization on at least one photovoltaic module in the photovoltaic system;
the obtaining module 10 is further configured to: respectively obtaining component voltages of corresponding photovoltaic components from the power optimizers; acquiring a voltage anomaly detection threshold;
the determining module 30 is further configured to determine that the photovoltaic module is a photovoltaic module with a dc arc fault if the module voltage of the photovoltaic module is smaller than the voltage anomaly detection threshold.
Further, the obtaining module 10 is further configured to:
and when the suspicious direct current arc fault is judged not to occur based on the first arc signal characteristic or the power optimizer in the photovoltaic system is judged to be in communication based on the first communication signal characteristic, returning to execute the operation of acquiring the direct current side alternating current signal of the inverter in the photovoltaic system.
Further, the extraction module 20 is further configured to:
converting the time domain to the frequency domain of the alternating current signal at the direct current side to obtain a frequency domain signal;
and performing feature extraction on a signal of a preset arc detection frequency band in the frequency domain signal to obtain a first arc signal feature, wherein the feature extraction at least comprises one or more items of a mean value, a root mean square value, a variance and a kurtosis of the signal in the preset arc detection frequency band.
Further, the obtaining module 10 is further configured to obtain a currently set arc fault detection sensitivity value;
the photovoltaic system direct current arc fault detection device still includes:
the selection module is used for selecting the arc fault judgment threshold value corresponding to the currently set arc fault detection sensitivity value from the arc fault judgment threshold values corresponding to various preset sensitivity values as a target threshold value;
and the second comparison module is used for comparing the first arc signal characteristic with the target threshold value and judging whether a suspicious direct current arc fault occurs or not based on the comparison result.
Further, the photovoltaic system direct current arc fault detection device further includes:
the control module is used for controlling the inverter to perform fault shutdown so as to report an arc fault; and when a preset self-starting condition is met and the continuous time of the fault shutdown of the inverter reaches a preset time, controlling the inverter to be started, and executing the operation of acquiring the direct-current side alternating-current signal of the inverter in the photovoltaic system.
The extension of the specific implementation of the dc arc fault detection apparatus of the photovoltaic system of the present invention is substantially the same as that of each embodiment of the dc arc fault detection method of the photovoltaic system, and is not described herein again.
In addition, an embodiment of the present invention further provides a computer-readable storage medium, where a photovoltaic system dc arc fault detection program is stored on the storage medium, and when being executed by a processor, the photovoltaic system dc arc fault detection program implements the following steps of the photovoltaic system dc arc fault detection method.
The embodiments of the photovoltaic system dc arc fault detection apparatus and the computer-readable storage medium of the present invention can refer to the embodiments of the photovoltaic system dc arc fault detection method of the present invention, and are not described herein again.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.
Through the above description of the embodiments, those skilled in the art will clearly understand that the method of the above embodiments can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware, but in many cases, the former is a better implementation manner. Based on such understanding, the technical solutions of the present invention may be embodied in the form of a software product, which is stored in a storage medium (such as ROM/RAM, magnetic disk, optical disk) and includes instructions for enabling a terminal device (such as a mobile phone, a computer, a server, an air conditioner, or a network device) to execute the method according to the embodiments of the present invention.
The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (12)
1. A photovoltaic system direct current arc fault detection method is characterized by comprising the following steps:
acquiring a direct-current side alternating-current signal of an inverter in the photovoltaic system;
extracting a signal characteristic of a preset arc detection frequency band in the direct current side alternating current signal as a first arc signal characteristic, and extracting a signal characteristic of a preset communication frequency band in the direct current side alternating current signal as a first communication signal characteristic;
and when the suspicious direct current arc fault is judged to occur based on the first arc signal characteristic and the power optimizer in the photovoltaic system is judged not to be in communication based on the first communication signal characteristic, determining that the real direct current arc fault occurs in the photovoltaic system.
2. The method for detecting a dc arc fault in a photovoltaic system according to claim 1, wherein after the step of extracting the signal feature of the preset arc detection frequency band in the dc-side ac signal as the first arc signal feature, the method further comprises:
acquiring a preset historical data set;
calculating to obtain an arc fault judgment threshold value based on each second arc signal characteristic in the historical data set;
and comparing the first arc signal characteristic with the arc fault determination threshold, and determining whether a suspicious direct current arc fault occurs or not based on the comparison result.
3. The method according to claim 2, wherein after the step of extracting the signal characteristic of the preset arc detection frequency band in the dc-side ac signal as the first arc signal characteristic and the signal characteristic of the preset communication frequency band in the dc-side ac signal as the first communication signal characteristic, the method further comprises:
adding the first arc signature to the historical data set when it is determined that a power optimizer in the photovoltaic system is not communicating based on the first communication signature.
4. The method according to claim 2, wherein the step of calculating an arc fault determination threshold based on the second arc signal characteristics in the historical data set comprises:
and calculating the mean value of the characteristics of each second arc signal in the historical data set, and multiplying the mean value by a preset multiple to obtain the arc fault judgment threshold value.
5. The method according to claim 1, wherein the photovoltaic system comprises a plurality of power optimizers, one of the power optimizers is used for power optimization of at least one photovoltaic module in the photovoltaic system;
after the step of determining that the photovoltaic system has a real dc arc fault, the method further includes:
respectively obtaining component voltages of corresponding photovoltaic components from each power optimizer;
acquiring a voltage abnormity detection threshold value;
and if the voltage of the photovoltaic module is smaller than the voltage abnormity detection threshold value, determining that the photovoltaic module is the photovoltaic module with the direct current arc fault.
6. The method according to claim 1, wherein after the step of extracting the signal characteristic of the preset arc detection frequency band in the dc-side ac signal as the first arc signal characteristic and the signal characteristic of the preset communication frequency band in the dc-side ac signal as the first communication signal characteristic, the method further comprises:
and when the suspicious direct current arc fault is judged not to occur based on the first arc signal characteristic or the power optimizer in the photovoltaic system is judged to be in communication based on the first communication signal characteristic, returning to execute the step of acquiring the direct current side alternating current signal of the inverter in the photovoltaic system.
7. The method for detecting the direct-current arc fault of the photovoltaic system according to claim 1, wherein the step of extracting the signal characteristic of the preset arc detection frequency band in the direct-current side alternating-current signal as the first arc signal characteristic comprises:
converting the time domain to the frequency domain of the alternating current signal at the direct current side to obtain a frequency domain signal;
and performing feature extraction on a signal of a preset arc detection frequency band in the frequency domain signal to obtain a first arc signal feature, wherein the feature extraction at least comprises one or more items of a mean value, a root mean square value, a variance and a kurtosis of the signal in the preset arc detection frequency band.
8. The method for detecting a dc arc fault in a photovoltaic system according to claim 1, wherein after the step of extracting the signal feature of the preset arc detection frequency band in the dc-side ac signal as the first arc signal feature, the method further comprises:
acquiring a currently set arc fault detection sensitivity value;
selecting an arc fault judgment threshold value corresponding to the currently set arc fault detection sensitivity value from arc fault judgment threshold values corresponding to various preset sensitivity values as a target threshold value;
and comparing the first arc signal characteristic with the target threshold value, and judging whether a suspicious direct current arc fault occurs or not based on the comparison result.
9. The method according to any one of claims 1 to 8, wherein after the step of determining that a real dc arc fault occurs in the photovoltaic system when it is determined that a suspected dc arc fault occurs based on the first arc signal characteristic and it is determined that a power optimizer in the photovoltaic system is not communicating based on the first communication signal characteristic, the method further comprises:
controlling the inverter to perform fault shutdown so as to report an arc fault;
and when a preset self-starting condition is met and the continuous time of the fault shutdown of the inverter reaches a preset time, controlling the inverter to be started, and executing the step of acquiring the direct-current side alternating current signal of the inverter in the photovoltaic system.
10. A photovoltaic system direct current arc fault detection device, characterized in that, photovoltaic system direct current arc fault detection device includes:
the acquisition module is used for acquiring a direct-current side alternating-current signal of an inverter in the photovoltaic system;
the extraction module is used for extracting a signal characteristic of a preset arc detection frequency band in the direct current side alternating current signal as a first arc signal characteristic and extracting a signal characteristic of a preset communication frequency band in the direct current side alternating current signal as a first communication signal characteristic;
and the determining module is used for determining that the photovoltaic system has a real direct current arc fault when the suspicious direct current arc fault is determined to occur based on the first arc signal characteristic and the power optimizer in the photovoltaic system is determined not to be in communication based on the first communication signal characteristic.
11. A photovoltaic system DC arc fault detection device, comprising: a memory, a processor, and a photovoltaic system dc arc fault detection program stored on the memory and executable on the processor, the photovoltaic system dc arc fault detection program when executed by the processor implementing the steps of the photovoltaic system dc arc fault detection method of any of claims 1 to 9.
12. A computer readable storage medium, characterized in that the computer readable storage medium has stored thereon a photovoltaic system dc arc fault detection program, which when executed by a processor implements the steps of the photovoltaic system dc arc fault detection method according to any one of claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210614970.5A CN115021676A (en) | 2022-06-01 | 2022-06-01 | Photovoltaic system direct current arc fault detection method, device, equipment and medium |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210614970.5A CN115021676A (en) | 2022-06-01 | 2022-06-01 | Photovoltaic system direct current arc fault detection method, device, equipment and medium |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115021676A true CN115021676A (en) | 2022-09-06 |
Family
ID=83070529
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210614970.5A Pending CN115021676A (en) | 2022-06-01 | 2022-06-01 | Photovoltaic system direct current arc fault detection method, device, equipment and medium |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115021676A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2023231404A1 (en) * | 2022-06-01 | 2023-12-07 | 阳光电源股份有限公司 | Photovoltaic system direct-current arc fault detection method, apparatus and device, and medium |
-
2022
- 2022-06-01 CN CN202210614970.5A patent/CN115021676A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2023231404A1 (en) * | 2022-06-01 | 2023-12-07 | 阳光电源股份有限公司 | Photovoltaic system direct-current arc fault detection method, apparatus and device, and medium |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP2806518B1 (en) | Serial arc detection based on harmonic content of DC current signal | |
| WO2016191187A1 (en) | Communication-less fault section identification for hybrid hvdc transmission systems | |
| EP3923434A1 (en) | Energy storage system electric arc detection and protection method and related device | |
| AU2019431775B9 (en) | Power conversion apparatus, and method controlling output impedance of power conversion apparatus | |
| CN115021676A (en) | Photovoltaic system direct current arc fault detection method, device, equipment and medium | |
| CN114696742B (en) | Photovoltaic system direct current arc fault detection method, device, equipment and medium | |
| US10103545B2 (en) | Method and system for detecting islanding effect in power electrical network topology | |
| CN112582978B (en) | Leakage protection method and device and charging pile | |
| JP2014128191A (en) | Methods for locating ground faults and insulation degradation condition in energy conversion systems | |
| US11329471B2 (en) | Arc detection circuit, breaker system, connection box system, power conditioner, micro inverter, DC optimizer, and arc detection method | |
| JP2005024469A (en) | Higher harmonic monitoring system, and higher harmonic monitoring method | |
| EP4206699A1 (en) | Abnormality detection device, abnormality detection method, and program | |
| KR101277141B1 (en) | Electric watt-hour meter and method for monitoring power distribution system | |
| CN113381693B (en) | Alternating current fault identification method for inverter and photovoltaic system | |
| CN113282160B (en) | UPS service life prediction method, equipment and computer readable storage medium | |
| CN110649651B (en) | Alternating current-direct current bidirectional converter, adaptive method thereof and electronic device | |
| CN110320469B (en) | Method and instrument for detecting shutoff device | |
| KR101413788B1 (en) | Method and apparratus of malfunction detection of transformer | |
| CN112084662A (en) | Method and device for detecting electrical service life of circuit breaker | |
| CN115616364B (en) | Fault arc detection method, device, equipment and storage medium | |
| EP4296697A1 (en) | Method and system of detection of dropped loads resulting from an electrical power quality event | |
| CN115308549A (en) | Arc detection method, electronic device and inverter | |
| US20240039473A1 (en) | System and method for determining the operating state of solar photovoltaic modules | |
| CN110247383B (en) | Method and device for eliminating ferromagnetic resonance in active compensation system | |
| CN117148049B (en) | Direct current arc discharge fault detection system, method and photovoltaic grid-connected system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |