Arc detection method, electronic equipment and inverter

Abstract

The present invention discloses an arc detection method, an electronic device and an inverter. The method comprises: during an IV scan of a photovoltaic system, determining whether the output voltage of a photovoltaic string of the photovoltaic system is adjusted; if the output voltage of the photovoltaic string of the photovoltaic system is adjusted, stopping the arc detection; when the output current of the photovoltaic string meets a preset condition, determining an arc characteristic value according to the output voltage of the photovoltaic string and the output current of the photovoltaic string; determining an arc detection result according to the arc characteristic value, thereby solving the problem of inaccurate arc detection caused by turning on the arc detection function during the IV scan. The technical solution of the present application improves the accuracy of arc detection during the IV scan, thereby improving the protection of the photovoltaic system against arcs.

Description

Technical Field

[0001] The present invention relates to the technical field of arc detection, and in particular to an arc detection method, electronic equipment and an inverter. Background Art

[0002] With the increasing use of photovoltaic energy in power system scenarios, the frequency of fire accidents caused by DC arcs has also increased. The arc is a gas discharge phenomenon. In the photovoltaic system, once a fault arc occurs, if effective protection is not adopted, it will cause serious safety accidents. Therefore, in practical applications, a DC arc detection device can be configured to extract time domain and frequency domain characteristic signals for analysis and processing to determine whether an arc has occurred and take corresponding protection measures. At the same time, the test of photovoltaic modules usually adopts IV scanning technology, which obtains the current and voltage data of the photovoltaic modules during operation, and then analyzes the health status of the photovoltaic modules based on the current and voltage data.

[0003] Currently, when the arc detection function is turned on during IV scanning, if a sudden change in voltage and current occurs during the IV scanning, it will interfere with the time domain and frequency domain characteristics of the arc detection, resulting in inaccurate arc detection. Summary of the invention

[0004] The embodiments of the present application provide an arc detection method, an electronic device, and an inverter, aiming to solve the problem of inaccurate arc detection when the arc detection function is turned on during IV scanning.

[0005] The embodiment of the present application provides an arc detection method, the arc detection method comprising:

[0006] During an IV scan of a photovoltaic system, determining whether an output voltage of a photovoltaic string of the photovoltaic system is adjusted;

[0007] If the output voltage of the photovoltaic strings of the photovoltaic system is adjusted, arc detection is stopped;

[0008] When the output current of the photovoltaic string meets a preset condition, determining an arc characteristic value according to the output voltage of the photovoltaic string and the output current of the photovoltaic string;

[0009] An arc detection result is determined according to the arc characteristic value.

[0010] Optionally, during the IV scanning of the photovoltaic system, the step of determining whether the output voltage of the photovoltaic strings of the photovoltaic system is adjusted comprises:

[0011] During the period when the IV scanning device of the photovoltaic system performs an IV scan, obtaining the output voltage of the photovoltaic string;

[0012] Determining whether the output voltage of the photovoltaic string reaches a preset voltage;

[0013] If the output voltage of the photovoltaic string does not reach the preset voltage, it is determined that the output voltage of the photovoltaic string needs to be adjusted.

[0014] Optionally, if the output voltage of the photovoltaic strings of the photovoltaic system is adjusted, the step of stopping arc detection includes:

[0015] If the output voltage of the photovoltaic strings of the photovoltaic system is adjusted, a voltage adjustment signal is sent to the arc detection device of the photovoltaic system to control the arc detection device to stop arc detection.

[0016] Optionally, when the output current of the photovoltaic string meets a preset condition, the step of determining the arc characteristic value according to the output voltage of the photovoltaic string and the output current of the photovoltaic string includes:

[0017] Acquire an output current corresponding to the output voltage of each of the photovoltaic strings within a preset time period of stopping the arc detection, wherein the preset time period is less than a photovoltaic string voltage adjustment period;

[0018] Determining whether the output current is within a preset current range;

[0019] If yes, the arc characteristic value is determined according to the output voltage and the output current of the photovoltaic string.

[0020] Optionally, when the output current of the photovoltaic string meets a preset condition, the step of determining the arc characteristic value according to the output voltage of the photovoltaic string and the output current of the photovoltaic string includes:

[0021] After a preset time period, the arc characteristic value is determined according to the output voltage and the output current of the photovoltaic string, and the preset time period is less than a voltage adjustment period of the photovoltaic string.

[0022] Optionally, the difference between the photovoltaic string voltage adjustment period and the preset time length is the arc detection time length during which the output voltage of the photovoltaic string is adjusted once during the IV scan.

[0023] Optionally, the method further comprises:

[0024] Detecting whether the IV scan is performed;

[0025] If so, the step of determining whether the output voltage of the photovoltaic strings of the photovoltaic system is adjusted during the IV scan of the photovoltaic system is performed.

[0026] Optionally, after the step of determining the arc detection result according to the arc characteristic value, the method further includes:

[0027] When the arc detection result indicates that an arc fault occurs, the inverter is controlled to be shut down.

[0028] Optionally, during the IV scanning of the photovoltaic system, after the step of determining whether the output voltage of the photovoltaic strings of the photovoltaic system is adjusted, the method further comprises:

[0029] If the output voltage of the photovoltaic string does not need to be adjusted, determining a scanning sample set of the photovoltaic string according to the output voltage of the photovoltaic string, the output current of the photovoltaic string and the open circuit voltage of the photovoltaic string;

[0030] An IV scanning curve is generated according to the scanning sample set.

[0031] Optionally, determining the arc characteristic value according to the output voltage of the photovoltaic string and the output current of the photovoltaic string includes:

[0032] Performing a fast Fourier analysis on the output voltage of the photovoltaic string, the output current and the open circuit voltage of the photovoltaic string to obtain an analysis result;

[0033] Acquire arc characteristics, wherein the arc characteristics include at least one of a mean value, a root mean square value, a variance, and a kurtosis;

[0034] Based on the analysis result, the arc characteristic value corresponding to the arc characteristic is calculated according to the characteristic calculation method of the arc characteristic.

[0035] In addition, to achieve the above-mentioned purpose, the present invention also provides an electronic device, which includes: a memory, a processor, and an arc detection program stored in the memory and executable on the processor, wherein the arc detection program implements the steps of the above-mentioned arc detection method when executed by the processor.

[0036] In addition, to achieve the above-mentioned purpose, the present invention also provides an inverter, which includes an arc detection device, an IV scanning device and an electronic device, and the arc detection device and the IV scanning device are communicatively connected.

[0037] Optionally, the arc detection device and the IV scanning device are integrated.

[0038] The technical scheme of an arc detection method, an electronic device and an inverter provided in the embodiment of the present application is adopted to determine whether the output voltage of the photovoltaic string of the photovoltaic system is adjusted during the IV scanning of the photovoltaic system, stop arc detection if the output voltage of the photovoltaic string of the photovoltaic system is adjusted, determine arc characteristic values ​​according to the output voltage and output current of the photovoltaic string when the output current of the photovoltaic string meets the preset conditions, and then determine the arc detection result according to the arc characteristic values. Since the IV scanning device is judged whether the IV scanning device is working by detecting whether the output voltage of the photovoltaic string of the photovoltaic system occurs during the IV scanning, the arc detection function is shielded when the IV scanning device is working, and the output current tracking adjustment of the photovoltaic string of the photovoltaic system is stabilized before the arc fault is normally detected and identified, thereby solving the problem of inaccurate arc detection caused by the interference of the sudden change of the output voltage and output current of the photovoltaic string on the arc detection during the IV scanning, improving the accuracy of arc detection, and thus improving the protection of the photovoltaic system against arc. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of the structure of a photovoltaic system involved in an embodiment of the present invention;

[0040] Figure 2 A schematic diagram of the structure of an inverter involved in an embodiment of the present invention;

[0041] Figure 3 A schematic diagram of the structure of an electronic device involved in an embodiment of the present invention;

[0042] Figure 4 It is a schematic diagram of the flow chart of the first embodiment of the arc detection method of the present invention;

[0043] Figure 5 A schematic diagram of a flow chart of arc fault detection during IV scanning of the present invention;

[0044] Figure 6 It is a schematic diagram of the flow of the present invention performing arc detection function according to the IV scanning voltage adjustment signal;

[0045] Figure 7 Schematic diagram of the relationship between the photovoltaic string voltage adjustment period and the preset duration of the present invention.

[0046] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. The above-mentioned drawings are only an embodiment diagram, not the entire invention. DETAILED DESCRIPTION

[0047] The present application aims to solve the problem of inaccurate arc detection caused by the interference of sudden changes in the output voltage and output current of the photovoltaic strings during IV scanning on arc detection. The present application proposes an arc detection method, which uses a method to determine whether the output voltage of the photovoltaic strings of the photovoltaic system is adjusted during the IV scanning of the photovoltaic system. If the output voltage of the photovoltaic strings of the photovoltaic system is adjusted, the arc detection is stopped. When the output current of the photovoltaic strings meets the preset conditions, the arc characteristic value is determined according to the output voltage and output current of the photovoltaic strings, and then the arc detection result is determined according to the arc characteristic value. The technical solution. Since it is determined whether the IV scanning device is working by detecting whether the output voltage of the photovoltaic strings of the photovoltaic system occurs during the IV scanning, when the IV scanning device is working, the arc detection function is shielded, and the output current tracking and adjustment of the photovoltaic strings of the photovoltaic system is stabilized before the arc fault is normally detected and identified, the accuracy of arc detection is improved, and the protection of the photovoltaic system against arc is improved.

[0048] In order to better understand the above technical solution, exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0049] like Figure 1 As shown, Figure 1 The schematic diagram of the structure of the photovoltaic system involved in the embodiment of the present invention. The photovoltaic system of the present application includes at least one photovoltaic string (PV), and each photovoltaic string includes at least one photovoltaic module, an inverter, a power grid and a load. Among them, the inverter is connected to the power grid and an optional load. Optionally, when each photovoltaic string includes multiple photovoltaic modules, each photovoltaic module is connected in series.

[0050] Optionally, a combiner box may be included between the photovoltaic string and the inverter, and the combiner box is connected to m photovoltaic strings. The combiner box is used to obtain the open circuit voltage of the photovoltaic string and send the open circuit voltage of the photovoltaic string to the electronic device; the inverter is used to determine the scanning initial voltage according to the open circuit voltage of the photovoltaic string, and control the output voltage of the photovoltaic string to gradually change from the scanning initial voltage to the preset voltage lower limit value based on the first preset step size.

[0051] Optionally, the combiner box is further used to obtain the output current of the photovoltaic string at the output voltage of each photovoltaic string, and send the output voltage and the output current of the photovoltaic string to the electronic device. Optionally, the electronic device is used to determine the scan sample set of each photovoltaic string according to the open circuit voltage of the photovoltaic string, the output voltage of the photovoltaic string, and the output current of the photovoltaic string.

[0052] Those skilled in the art will understand that Figure 1 The structure of the photovoltaic system shown in the figure does not constitute a limitation on the photovoltaic system, and may include more or less components than shown in the figure, or combine certain components, or arrange the components differently.

[0053] like Figure 2 As shown, Figure 2 This is a schematic diagram of the structure of the inverter of the present application. An arc detection device and an IV scanning device are included in the inverter, and the arc detection device and the IV scanning device are communicatively connected. Optionally, the inverter also includes an electronic device that can store programs, variables, and support information interaction. The electronic device is connected to the arc detection device and the IV scanning device, respectively. Optionally, the arc detection device and the IV scanning device can also be integrated in the same device, and the device is connected to the electronic device. Optionally, the electronic device can be integrated with the inverter.

[0054] Optionally, the inverter is also used to boost the DC bus voltage so that the current flows from the inverter to the photovoltaic string in a first direction, and to step down the DC bus voltage until the current flows from the photovoltaic component to the inverter in a second direction, and the second direction is opposite to the first direction; the junction box is also used to determine the DC bus voltage at the moment when the current flow direction is reversed as the open circuit voltage of the photovoltaic string.

[0055] Optionally, after the string output voltage value reaches a preset voltage lower limit, the inverter and / or the combiner box starts the DC short-circuit mode; the combiner box collects the short-circuit current flowing through the photovoltaic string in the DC short-circuit mode, and sends the short-circuit current to the electronic device; the electronic device adds the short-circuit current value to the scan sample set.

[0056] Optionally, the electronic device is also used to perform data fitting according to the scanning sample set after obtaining the scanning sample set of each photovoltaic string, so as to determine the IV scanning curve of the photovoltaic string, wherein the scanning starting point of the IV scanning curve of the photovoltaic string is the open circuit voltage of the corresponding photovoltaic string.

[0057] Those skilled in the art will understand that Figure 2 The structure of the inverter shown in the figure does not constitute a limitation of the inverter, and the inverter may include more or less components than those shown in the figure, or combine certain components, or arrange the components differently.

[0058] like Figure 3 As shown, Figure 3 It is a schematic diagram of the structure of an electronic device involved in an embodiment of the present invention.

[0059] like Figure 3As shown, the electronic device may include: a processor 1001, such as a CPU, a memory 1005, a user interface 1003, a network interface 1004, and a communication bus 1002. Among them, the communication bus 1002 is used to realize the connection and communication between these components. The user interface 1003 may include a display screen (Display), an input unit such as a keyboard (Keyboard), and the optional user interface 1003 may also include a standard wired interface and a wireless interface. The network interface 1004 may optionally include a standard wired interface and a wireless interface (such as a WI-FI interface). The memory 1005 may be a high-speed RAM memory, or a stable memory (non-volatile memory), such as a disk memory. The memory 1005 may also be a storage device independent of the aforementioned processor 1001.

[0060] Those skilled in the art will understand that Figure 3 The structure of the electronic device shown in the figure does not constitute a limitation of the electronic device, and may include more or less components than shown in the figure, or combine certain components, or arrange the components differently.

[0061] like Figure 3 As shown, the memory 1005 as a storage medium may include an operating system, a network communication module, a user interface module and an arc detection program. The operating system is a program that manages and controls the hardware and software resources of electronic equipment, the arc detection program and the operation of other software or programs.

[0062] exist Figure 3 In the electronic device shown, the user interface 1003 is mainly used to connect to the terminal and communicate data with the terminal; the network interface 1004 is mainly used for the background server and communicates data with the background server; the processor 1001 can be used to call the arc detection program stored in the memory 1005.

[0063] In this embodiment, the electronic device includes: a memory 1005, a processor 1001, and an arc detection program stored in the memory and executable on the processor, wherein:

[0064] When the processor 1001 calls the arc detection program stored in the memory 1005, the following operations are performed:

[0065] During an IV scan of a photovoltaic system, determining whether an output voltage of a photovoltaic string of the photovoltaic system is adjusted;

[0066] If the output voltage of the photovoltaic strings of the photovoltaic system is adjusted, arc detection is stopped;

[0067] When the output current of the photovoltaic string meets a preset condition, determining an arc characteristic value according to the output voltage of the photovoltaic string and the output current of the photovoltaic string;

[0068] An arc detection result is determined according to the arc characteristic value.

[0069] When the processor 1001 calls the arc detection program stored in the memory 1005, it also performs the following operations:

[0070] During the period when the IV scanning device of the photovoltaic system performs an IV scan, obtaining the output voltage of the photovoltaic string;

[0071] Determining whether the output voltage of the photovoltaic string reaches a preset voltage;

[0072] If the output voltage of the photovoltaic string does not reach the preset voltage, it is determined that the output voltage of the photovoltaic string needs to be adjusted.

[0073] If the output voltage of the photovoltaic strings of the photovoltaic system is adjusted, a voltage adjustment signal is sent to the arc detection device of the photovoltaic system to control the arc detection device to stop arc detection.

[0074] When the processor 1001 calls the arc detection program stored in the memory 1005, it also performs the following operations:

[0075] Acquire an output current corresponding to the output voltage of each of the photovoltaic strings within a preset time period of stopping the arc detection, wherein the preset time period is less than a photovoltaic string voltage adjustment period;

[0076] Determining whether the output current is within a preset current range;

[0077] If yes, the arc characteristic value is determined according to the output voltage and the output current of the photovoltaic string.

[0078] When the processor 1001 calls the arc detection program stored in the memory 1005, it also performs the following operations:

[0079] After a preset time period, the arc characteristic value is determined according to the output voltage and the output current of the photovoltaic string, and the preset time period is less than a voltage adjustment period of the photovoltaic string.

[0080] When the processor 1001 calls the arc detection program stored in the memory 1005, it also performs the following operations:

[0081] The difference between the photovoltaic string voltage adjustment period and the preset time length is the arc detection time length during which the output voltage of the photovoltaic string is adjusted once during the IV scan.

[0082] When the processor 1001 calls the arc detection program stored in the memory 1005, it also performs the following operations:

[0083] Detecting whether the IV scan is performed;

[0084] If so, the step of determining whether the output voltage of the photovoltaic strings of the photovoltaic system is adjusted during the IV scan of the photovoltaic system is performed.

[0085] When the processor 1001 calls the arc detection program stored in the memory 1005, it also performs the following operations:

[0086] When the arc detection result indicates that an arc fault occurs, the inverter is controlled to be shut down.

[0087] When the processor 1001 calls the arc detection program stored in the memory 1005, it also performs the following operations:

[0088] If the output voltage of the photovoltaic string does not need to be adjusted, determining a scanning sample set of the photovoltaic string according to the output voltage of the photovoltaic string, the output current of the photovoltaic string and the open circuit voltage of the photovoltaic string;

[0089] An IV scanning curve is generated according to the scanning sample set.

[0090] When the processor 1001 calls the arc detection program stored in the memory 1005, it also performs the following operations:

[0091] Performing a fast Fourier analysis on the output voltage of the photovoltaic string, the output current and the open circuit voltage of the photovoltaic string to obtain an analysis result;

[0092] Acquire arc characteristics, wherein the arc characteristics include at least one of a mean value, a root mean square value, a variance, and a kurtosis;

[0093] Based on the analysis result, the arc characteristic value corresponding to the arc characteristic is calculated according to the characteristic calculation method of the arc characteristic.

[0094] The technical solution of the present application will be described below in the form of embodiments.

[0095] First embodiment.

[0096] like Figure 4 As shown, in the first embodiment of the present application, the arc detection method of the present application is applied to an electronic device of an inverter, and the arc detection method of the present application includes the following steps:

[0097] Step S110 , during the IV scan of the photovoltaic system, determining whether the output voltage of the photovoltaic strings of the photovoltaic system is adjusted.

[0098] In this embodiment, during the IV scan of the photovoltaic system, the arc detection function is executed or the arc detection is stopped for a preset time period, depending on whether the output voltage of the photovoltaic string is adjusted. That is, during the IV scan, if the string voltage is adjusted according to the preset step length, the arc detection function is stopped for a preset time period, and after the string current is stable, the arc detection function is turned on for normal detection to prevent the influence of voltage and current mutations on the time domain and frequency domain characteristic signals of arc detection. If the inverter does not perform IV scanning, the arc detection function is performed normally.

[0099] Among them, during the IV scanning of the photovoltaic system, the IV data of the photovoltaic module will be generated; IV data refers to the current-voltage data of the photovoltaic module during operation. Since IV data can directly reflect the health status of the photovoltaic module, the IV scanning function of obtaining the IV data of the photovoltaic module is an important technology for the photovoltaic system to evaluate its power generation capacity and diagnose faults. The specific process is: the inverter dynamically changes the size of the photovoltaic module load, and starts scanning from the open circuit voltage (i.e., the maximum voltage) of the photovoltaic module until the photovoltaic module voltage approaches zero voltage, and obtains a set of two-dimensional arrays of different voltages and currents. An IV curve is constructed based on the discrete data in all the two-dimensional arrays, and feature recognition is performed through the IV curve to determine whether the photovoltaic module is blocked, damaged, or has abnormal conditions such as hot spots.

[0100] In this embodiment, during the IV scanning of the photovoltaic system, within the voltage adjustment cycle of each photovoltaic string, the output voltage of each photovoltaic string of the photovoltaic system will be adjusted according to a preset step size, that is, the output voltage of each photovoltaic string of the photovoltaic system will be gradually adjusted from the open circuit voltage to the preset voltage according to the preset step size. Among them, since there are multiple photovoltaic strings in the photovoltaic system, the open circuit voltage of each photovoltaic string can be obtained; the maximum open circuit voltage of each open circuit voltage is determined, and the initial scanning voltage is determined according to the maximum open circuit voltage, and the initial scanning voltage is greater than or equal to the maximum open circuit voltage, so that the output voltage of the photovoltaic string of the photovoltaic system is gradually adjusted from the initial scanning voltage to the preset voltage according to the preset step size.

[0101] Optionally, during the IV scanning of the photovoltaic system, the step of determining whether the output voltage of the photovoltaic strings of the photovoltaic system is adjusted comprises:

[0102] Step S111, obtaining the output voltage of the photovoltaic string during the IV scanning performed by the IV scanning device of the photovoltaic system;

[0103] Step S112, determining whether the output voltage of the photovoltaic string reaches a preset voltage;

[0104] Step S113: if the output voltage of the photovoltaic string does not reach the preset voltage, it is determined that the output voltage of the photovoltaic string needs to be adjusted.

[0105] In this embodiment, IV scanning is a function performed by an IV scanning device of a photovoltaic system controlled by an electronic device. During the period when the IV scanning device of the photovoltaic system performs IV scanning, the output voltage of the photovoltaic string is gradually adjusted from the open circuit voltage to the preset voltage. The preset voltage can be set according to actual conditions, for example, the preset voltage can be zero voltage; or all voltages between the open circuit voltage and the zero voltage can be divided into multiple voltage intervals according to actual conditions, and the preset voltage can be the lower limit of a voltage interval.

[0106] Optionally, during the IV scanning of the photovoltaic system's IV scanning device, the electronic device acquires the output voltage of the photovoltaic string in real time and determines the relationship between the output voltage of the photovoltaic string and a preset voltage. The relationship between the output voltage of the photovoltaic string and the preset voltage may be determined as follows: when the difference between the output voltage and the preset voltage is greater than 0, it indicates that the output voltage has not reached the preset voltage; when the difference between the output voltage and the preset voltage is less than 0, it indicates that the output voltage has reached the preset voltage.

[0107] Optionally, when the output voltage of the photovoltaic string does not reach the preset voltage, it is determined that the output voltage of the photovoltaic string still needs to be adjusted, and the output voltage of the photovoltaic string continues to be adjusted based on the preset step size. Optionally, when the output voltage of the photovoltaic string reaches the preset voltage, it is determined that the output voltage of the photovoltaic string does not need to be adjusted, which means that there will be no sudden changes in current and voltage at this time, and the normal arc detection function can be performed at this time.

[0108] Optionally, a photovoltaic string voltage adjustment cycle may be set, and voltage adjustment may be performed in each photovoltaic string voltage adjustment cycle. Timing may be started at each voltage adjustment, for example, the first timing is when the open circuit voltage is scanned. After the timing is over, a new photovoltaic string voltage adjustment cycle is restarted, and the voltage is adjusted downward. Therefore, arc detection may be stopped at each photovoltaic string voltage adjustment cycle, that is, when the voltage adjustment timing starts.

[0109] According to the above technical solution, during the IV scanning device of the photovoltaic system performs IV scanning, the electronic device in the inverter obtains the output voltage of the photovoltaic string, determines whether the output voltage of the photovoltaic string reaches a preset voltage, and when the output voltage of the photovoltaic string does not reach the preset voltage, determines that the output voltage of the photovoltaic string needs to be adjusted, thereby monitoring the voltage adjustment status of the photovoltaic string in real time, so that the IV scanning device can perform the IV scanning function normally.

[0110] Step S120 , if the output voltage of the photovoltaic strings of the photovoltaic system is adjusted, arc detection is stopped.

[0111] In this embodiment, arc detection is performed during the IV scanning of the photovoltaic system. When the output voltage of the photovoltaic strings of the photovoltaic system is adjusted, the output voltage and output current of the photovoltaic strings may suddenly change, and the sudden change of the output voltage and output current may make the arc detection result inaccurate. Therefore, when the output voltage of the photovoltaic strings of the photovoltaic system is adjusted, the arc detection function needs to be stopped. Optionally, when the arc detection function is stopped, the IV scanning function will continue.

[0112] Optionally, when the output voltage of the photovoltaic strings of the photovoltaic system is adjusted, a voltage adjustment signal is sent to the arc detection device of the photovoltaic system to control the arc detection device to stop arc detection. Wherein, there is a communication connection function between the IV scanning device and the arc detection device. Optionally, when the output voltage of the photovoltaic strings of the photovoltaic system is adjusted, the IV scanning device synchronizes the IV scanning instruction and the voltage adjustment signal to the arc detection device, so that after the arc detection device receives the voltage adjustment signal and the IV scanning instruction, the arc detection device stops arc detection. Optionally, when the output voltage of the photovoltaic strings of the photovoltaic system is adjusted, the IV scanning device sends the IV scanning instruction and the voltage adjustment signal to the electronic device; after receiving the IV scanning instruction and the voltage adjustment signal sent by the IV scanning device, the electronic device generates a stop arc detection signal, and forwards the stop arc detection signal to the arc detection device, thereby controlling the arc detection device to stop arc detection.

[0113] According to the above technical solution, the present application stops the arc detection function when it is detected that the output voltage of the photovoltaic strings of the photovoltaic system is adjusted, thereby avoiding the phenomenon of inaccurate arc detection results caused by sudden changes in the output voltage and output current of the photovoltaic strings when the output voltage of the photovoltaic strings of the photovoltaic system is adjusted.

[0114] Step S130, when the output current of the photovoltaic string meets a preset condition, determining an arc characteristic value according to the output voltage of the photovoltaic string and the output current of the photovoltaic string.

[0115] In this embodiment, after stopping the arc detection function, it is further determined whether the output current of the photovoltaic string meets the preset conditions. When the output current of the photovoltaic string meets the preset conditions, the arc detection is restored. If the output current of the photovoltaic string does not meet the preset conditions, it is necessary to wait until the preset conditions are met before the arc detection can be restored. Among them, the output current of the photovoltaic string meets the preset conditions, which means that the output current of the photovoltaic string is stable, that is, there is no sudden change. If the output current of the photovoltaic string does not meet the preset conditions, that is, the output current of the photovoltaic string is unstable, it means that the output current suddenly changes during the process of adjusting the output voltage of the photovoltaic string. Among them, arc detection mainly extracts the time domain and frequency domain characteristic signals of the IV data generated during the IV scan (that is, the output voltage of the photovoltaic string and the output current of the photovoltaic string), that is, extracts the arc characteristic values, and then analyzes and processes them to determine whether an arc occurs.

[0116] Optionally, when the output current of the photovoltaic string meets a preset condition, the step of determining the arc characteristic value according to the output voltage of the photovoltaic string and the output current of the photovoltaic string includes:

[0117] Step S131, obtaining the output current corresponding to the output voltage of each photovoltaic string within a preset time length of stopping the arc detection, wherein the preset time length is less than a photovoltaic string voltage adjustment period;

[0118] Step S132, determining whether the output current is within a preset current range;

[0119] Step S133: If yes, determine the arc characteristic value according to the output voltage and the output current of the photovoltaic string.

[0120] In this embodiment, specifically, refer to Figure 7 , wherein the preset duration is the photovoltaic string current tracking adjustment duration, that is, the duration for current stability detection. The above preset duration is less than the photovoltaic string voltage adjustment cycle, and the difference between the photovoltaic string voltage adjustment cycle and the preset duration is the arc detection duration of the photovoltaic string output voltage adjustment once during the IV scan. The preset duration is determined by the speed at which the string current tracking adjustment stabilizes after the output voltage of the photovoltaic string is adjusted. The faster the string current adjustment speed, the shorter the preset duration. Under the condition that the total scanning duration requirement of the IV scanning function is met, the photovoltaic string voltage adjustment cycle, the stronger the arc detection function's arc recognition ability.

[0121] Optionally, after stopping the arc detection, the output current corresponding to the output voltage of the photovoltaic string at each moment within the preset time length of stopping the arc detection can be obtained. If the output current of the photovoltaic string is within the preset current range at each moment within the preset time length, it means that the output current of the photovoltaic string is stable, and then the arc detection can be started, that is, the arc characteristic value is determined according to the output voltage of the photovoltaic string and the output current of the photovoltaic string. If there are continuous output currents of the photovoltaic string that are not within the preset current range within the preset time length, it means that the output current of the photovoltaic string is unstable, and the arc detection cannot be started at this time.

[0122] The preset current range can be set according to actual conditions.

[0123] Optionally, the output current corresponding to the output voltage of all photovoltaic strings between the open circuit voltage and the zero voltage can be determined, that is, the preset current range can be the current interval corresponding to the output current corresponding to the open circuit voltage and the output current corresponding to the zero voltage, and then determine whether the output current corresponding to the output voltage of each photovoltaic string is within the preset current range. Optionally, after the output voltage between the open circuit voltage and the zero voltage is divided into a plurality of interval voltages according to actual conditions, each interval voltage corresponds to an interval current, and the interval current can be determined according to the interval voltage where the output voltage of the current photovoltaic string is located, and then the interval current is determined as the preset current range, and then determine whether the output current corresponding to the output voltage of each photovoltaic string is within the preset current range.

[0124] Optionally, the output current average value can be calculated based on the output current corresponding to the output voltage of each photovoltaic string within the preset time length of stopping arc detection, and it can be determined whether the current average value is within the preset current range. If so, arc detection is performed, that is, the arc characteristic value is determined based on the output voltage and output current of the photovoltaic string.

[0125] According to the above technical solution, the present application determines whether the output current corresponding to the output voltage of each photovoltaic string is within the preset current range within the preset time length of stopping arc detection. If the output current is within the preset current range, arc detection is performed, thereby avoiding false alarms of arc detection when the current and voltage suddenly change, thereby improving the protection of the photovoltaic system against arcs. At the same time, by setting the preset time length and the photovoltaic string voltage adjustment cycle, normal detection and identification of arc faults during IV scanning can be supported to prevent missed detection of arc initiation during IV scanning.

[0126] Optionally, when the output current of the photovoltaic string meets a preset condition, the step of determining the arc characteristic value according to the output voltage of the photovoltaic string and the output current of the photovoltaic string includes:

[0127] Step S231, after a preset time period, determining the arc characteristic value according to the output voltage and the output current of the photovoltaic string, wherein the preset time period is less than a photovoltaic string voltage adjustment period.

[0128] In this embodiment, the preset duration is less than the photovoltaic string voltage adjustment period, and the difference between the photovoltaic string voltage adjustment period and the preset duration is the arc detection duration of the photovoltaic string output voltage adjustment once during the IV scan. Optionally, after the preset duration, it may be automatically determined that the output current is within the preset current range, and then the arc detection is started, that is, after the preset duration, the arc characteristic value is determined according to the output voltage and output current of the photovoltaic string.

[0129] According to the above technical solution, the present application determines the arc characteristic value according to the output voltage and output current of the photovoltaic string after a preset time, thereby avoiding false alarms of arc detection when the current and voltage suddenly change, thereby improving the protection of the photovoltaic system against arcs. At the same time, by setting the preset time and the photovoltaic string voltage adjustment cycle, it can support normal detection and identification of arc faults during IV scanning, and prevent missed detection of arc initiation during IV scanning.

[0130] Optionally, when the output current of the photovoltaic string meets the preset conditions, the electronic device performs arc detection. In the process of arc detection, the built-in program of the arc detection device performs fast Fourier analysis on the collected signal and extracts arc features. Among them, the arc feature includes but is not limited to at least one of the mean, root mean square value, variance, and kurtosis. For example, the arc feature can be only the mean, or the mean and peak value, or the mean, root mean square value, variance, and kurtosis. Each arc feature has a corresponding feature calculation method, and a corresponding feature calculation method can be set for each arc feature according to actual conditions. Specifically, the specific process of arc detection can be: performing fast Fourier analysis on the output voltage of the photovoltaic string, the output current, and the open circuit voltage of the photovoltaic string to obtain an analysis result; obtaining arc features, the arc features including at least one of the mean, root mean square value, variance, and kurtosis; based on the analysis result, according to the feature calculation method of the arc feature, the arc feature value corresponding to the arc feature is calculated. Since the output voltage, output current and open circuit voltage of the photovoltaic string are analyzed and the corresponding arc characteristic values ​​are extracted in the above manner, the final arc detection result is more accurate.

[0131] Step S140, determining an arc detection result according to the arc characteristic value.

[0132] In this embodiment, after determining the arc characteristic value according to the above method, the arc detection result can be further determined according to the arc characteristic value. The arc detection result includes the occurrence of an arc fault and the absence of an arc fault. Optionally, the arc detection result can also be the output voltage and output current corresponding to the preset time period of the arc.

[0133] Optionally, the arc characteristic value and the preset threshold value can be compared. If the arc characteristic value is greater than the preset threshold value, it is determined that an arc occurs; if the arc characteristic value is less than or equal to the preset threshold value, it is determined that no arc occurs. Optionally, a corresponding preset threshold value can be set for each arc characteristic value according to the actual situation. When there are multiple arc characteristic values, it is determined that an arc occurs only when all arc characteristic values ​​are greater than the corresponding preset threshold value, otherwise, no arc occurs. Optionally, a corresponding weight and a corresponding preset threshold value can also be set for each arc characteristic value. When there are multiple arc characteristic values, the arc characteristic values ​​greater than the corresponding preset threshold value are extracted, and the final calculation result is calculated in combination with the corresponding weight. When the calculation result does not meet the preset condition, it is determined that an arc occurs, wherein the preset condition can be set according to the actual situation. Determining the arc detection result according to the arc characteristic value is not limited to the above method, and the arc detection result can also be determined according to the specific application scenario and the corresponding rules set according to the specific needs.

[0134] Optionally, when the arc detection result indicates that an arc fault has occurred, the inverter is controlled to shut down. The inverter stops due to a fault, an arc fault is reported, and maintenance personnel conduct line inspection to avoid major safety accidents.

[0135] According to the above technical solution, this embodiment adopts a technical solution of judging whether the output voltage of the photovoltaic strings of the photovoltaic system is adjusted during the IV scanning of the photovoltaic system, stopping arc detection if the output voltage of the photovoltaic strings of the photovoltaic system is adjusted, and determining arc characteristic values ​​according to the output voltage and output current of the photovoltaic strings when the output current of the photovoltaic strings meets the preset conditions, and then determining the arc detection result according to the arc characteristic values. Since the IV scanning device is judged whether it is working by detecting whether the output voltage of the photovoltaic strings of the photovoltaic system occurs during the IV scanning, the arc detection function is shielded when the IV scanning device is working, and the arc fault is normally detected and identified after the output current tracking adjustment of the photovoltaic strings of the photovoltaic system is stable, thereby solving the problem of inaccurate arc detection caused by the interference of the sudden change of the output voltage and output current of the photovoltaic strings during the IV scanning, improving the accuracy of arc detection, and thus improving the protection of the photovoltaic system against arc.

[0136] Second embodiment.

[0137] Based on the first embodiment and before step S110, in the second embodiment of the present application, the arc detection method of the present application includes the following steps:

[0138] Step S310, detecting whether the IV scan is performed;

[0139] If so, executing step S110, during the IV scan of the photovoltaic system, determining whether the output voltage of the photovoltaic strings of the photovoltaic system is adjusted;

[0140] Step S120, if the output voltage of the photovoltaic string of the photovoltaic system is adjusted, stop arc detection;

[0141] Step S130, when the output current of the photovoltaic string meets a preset condition, determining an arc characteristic value according to the output voltage of the photovoltaic string and the output current of the photovoltaic string;

[0142] Step S140, determining an arc detection result according to the arc characteristic value.

[0143] In this embodiment, during the inverter grid connection, the arc detection device takes the AC signal of the inverter DC side in real time; if the inverter does not perform the IV scanning function, the arc detection function is performed normally. If the inverter needs to perform the IV scanning function, the initial scanning voltage is determined by the open circuit voltage, and after the photovoltaic string voltage adjustment cycle, the output voltage of the photovoltaic string is adjusted downward according to the preset step size. At the same time, the IV scanning device transmits the IV scanning instruction and the voltage adjustment signal to the arc detection device; after the arc detection device receives the voltage adjustment signal, it stops arc detection for a preset time, and performs arc detection after the output current of the photovoltaic string is adjusted and stabilized.

[0144] Optionally, when it is detected that no arc occurs, it is also possible to re-detect whether the IV scan is performed, so that normal IV scans can be performed on all photovoltaic strings of the photovoltaic system and arc accuracy can be improved during the IV scan.

[0145] Specifically, refer to Figure 5 , first initialize the parameters. Then, check whether to perform IV scanning;

[0146] If IV scanning is performed, the arc detection function is performed according to the IV scanning voltage change signal to determine whether an arc occurs. If so, it means that an arc fault is detected. If not, re-detect whether to perform IV scanning.

[0147] If IV scanning is not performed, the arc detection function is performed normally. It is determined whether an arc occurs. If so, it indicates that an arc fault is detected. If not, it is re-detected whether to perform IV scanning.

[0148] Reference Figure 6 , Figure 6 The figure is a flow chart of the arc detection function according to the IV scanning voltage adjustment signal. Specifically, the process is as follows: first, perform IV scanning, and determine the initial voltage by the open circuit voltage. Then, when the voltage adjustment cycle of the photovoltaic string is reached, the voltage is adjusted according to the preset step length; then, stop the arc detection for a preset time and wait for the current to stabilize; then, when the current is stable, perform the arc detection function. While executing the arc detection function, return to the step of performing voltage adjustment according to the preset step length when the voltage adjustment cycle of the photovoltaic string is reached; finally, if the output voltage of the photovoltaic string is less than the lower limit of the preset voltage, end the IV scan.

[0149] According to the above technical solution, this embodiment adopts a technical means of detecting whether the IV scan is executed and executing the arc detection function according to the IV scan voltage change signal when the IV scan is executed. This solves the problem of inaccurate arc detection caused by the interference of sudden changes in the output voltage and output current of the photovoltaic string during the IV scan on the arc detection, improves the accuracy of arc detection, and further improves the protection of the photovoltaic system against arcs.

[0150] Third embodiment.

[0151] After the first implementation step S110, in a third embodiment of the present application, the arc detection method of the present application includes the following steps:

[0152] Step S110, during the IV scan of the photovoltaic system, determining whether the output voltage of the photovoltaic strings of the photovoltaic system is adjusted;

[0153] Step S410, if the output voltage of the photovoltaic string does not need to be adjusted, determining a scanning sample set of the photovoltaic string according to the output voltage of the photovoltaic string, the output current of the photovoltaic string and the open circuit voltage of the photovoltaic string;

[0154] Step S420: generating an IV scanning curve according to the scanning sample set.

[0155] In this embodiment, when the output voltage of the photovoltaic system does not need to be adjusted, the scanning sample set of each photovoltaic string is determined according to the open circuit voltage of the photovoltaic string, the output voltage of the photovoltaic string and the current of the photovoltaic string, and the IV scanning curve corresponding to each photovoltaic string is drawn to end the IV scanning. Then, feature recognition is performed through the IV curve to determine whether the photovoltaic module is blocked, damaged or has abnormal conditions such as hot spots.

[0156] According to the above technical solution, this embodiment adopts a technical means of generating an IV scanning curve when the output voltage of the photovoltaic string does not need to be adjusted. Since the abnormality of the photovoltaic component can be judged by the IV scanning curve, the safe maintenance of the photovoltaic system can be achieved.

[0157] The embodiments of the present invention provide embodiments of the arc detection method. It should be noted that although the logical order is shown in the flow chart, in some cases, the steps shown or described may be performed in a different order than here.

Claims

1. An arc detection method, characterized in that: The arc detection method comprises: During an IV scan of a photovoltaic system, determining whether an output voltage of a photovoltaic string of the photovoltaic system is adjusted; If the output voltage of the photovoltaic strings of the photovoltaic system is adjusted, arc detection is stopped; When the output current of the photovoltaic string meets a preset condition, determining an arc characteristic value according to the output voltage of the photovoltaic string and the output current of the photovoltaic string, wherein the preset condition is that the output current of the photovoltaic string is stable; An arc detection result is determined according to the arc characteristic value.

2. The arc detection method according to claim 1, characterized in that: During the IV scanning of the photovoltaic system, the step of determining whether the output voltage of the photovoltaic strings of the photovoltaic system is adjusted comprises: During the period when the IV scanning device of the photovoltaic system performs an IV scan, obtaining the output voltage of the photovoltaic string; Determining whether the output voltage of the photovoltaic string reaches a preset voltage; If the output voltage of the photovoltaic string does not reach the preset voltage, it is determined that the output voltage of the photovoltaic string needs to be adjusted.

3. The arc detection method according to claim 1, characterized in that: If the output voltage of the photovoltaic strings of the photovoltaic system is adjusted, the step of stopping arc detection includes: If the output voltage of the photovoltaic strings of the photovoltaic system is adjusted, a voltage adjustment signal is sent to the arc detection device of the photovoltaic system to control the arc detection device to stop arc detection.

4. The arc detection method according to claim 1, characterized in that: When the output current of the photovoltaic string meets a preset condition, the step of determining the arc characteristic value according to the output voltage of the photovoltaic string and the output current of the photovoltaic string comprises: Acquire an output current corresponding to the output voltage of each of the photovoltaic strings within a preset time period of stopping the arc detection, wherein the preset time period is less than a photovoltaic string voltage adjustment period; Determining whether the output current is within a preset current range; If yes, the arc characteristic value is determined according to the output voltage and the output current of the photovoltaic string.

5. The arc detection method according to claim 1, characterized in that: When the output current of the photovoltaic string meets a preset condition, the step of determining the arc characteristic value according to the output voltage of the photovoltaic string and the output current of the photovoltaic string comprises: After a preset time period, the arc characteristic value is determined according to the output voltage and the output current of the photovoltaic string, and the preset time period is less than a voltage adjustment period of the photovoltaic string.

6. The arc detection method according to claim 4 or 5, characterized in that: The difference between the photovoltaic string voltage adjustment period and the preset time length is the arc detection time length during which the output voltage of the photovoltaic string is adjusted once during the IV scan.

7. The arc detection method according to claim 1, characterized in that: The arc detection method further comprises: Detecting whether the IV scan is performed; If so, the step of determining whether the output voltage of the photovoltaic strings of the photovoltaic system is adjusted during the IV scan of the photovoltaic system is performed.

8. The arc detection method according to claim 1, characterized in that: After the step of determining the arc detection result according to the arc characteristic value, the method further includes: When the arc detection result indicates that an arc fault occurs, the inverter is controlled to be shut down.

9. The arc detection method according to claim 1, characterized in that: After the step of determining whether the output voltage of the photovoltaic strings of the photovoltaic system is adjusted during the IV scanning of the photovoltaic system, the method further comprises: If the output voltage of the photovoltaic string does not need to be adjusted, determining a scanning sample set of the photovoltaic string according to the output voltage of the photovoltaic string, the output current of the photovoltaic string and the open circuit voltage of the photovoltaic string; An IV scanning curve is generated according to the scanning sample set.

10. The arc detection method according to claim 1, characterized in that: Determining the arc characteristic value according to the output voltage of the photovoltaic string and the output current of the photovoltaic string comprises: Performing a fast Fourier analysis on the output voltage of the photovoltaic string, the output current and the open circuit voltage of the photovoltaic string to obtain an analysis result; Acquire arc characteristics, wherein the arc characteristics include at least one of a mean value, a root mean square value, a variance, and a kurtosis; Based on the analysis result, the arc characteristic value corresponding to the arc characteristic is calculated according to the characteristic calculation method of the arc characteristic.

11. An electronic device, characterized in that: The electronic device comprises: a memory, a processor, and an arc detection program stored in the memory and executable on the processor, wherein the arc detection program, when executed by the processor, implements the steps of the arc detection method according to any one of claims 1 to 10.

12. An inverter, characterized in that: The inverter includes an arc detection device, an IV scanning device, and the electronic device as claimed in claim 11, and the arc detection device and the IV scanning device are communicatively connected.

13. The inverter according to claim 12, characterized in that: The arc detection device and the IV scanning device are integrated.

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