Photovoltaic system DC arc fault detection method, device, equipment and medium

Abstract

The present invention discloses a method, apparatus, device, and computer-readable storage medium for detecting DC arc faults in a photovoltaic system. The method comprises obtaining an AC signal on the DC side of an inverter in the photovoltaic system; extracting a signal characteristic of a preset arc detection frequency band from the DC side AC signal as a first arc signal characteristic, and extracting a signal characteristic of a preset communication frequency band from the DC side AC signal as a first communication signal characteristic; and determining that a true DC arc fault has occurred in the photovoltaic system when a suspected DC arc fault is determined to have occurred based on the first arc signal characteristic, and when a power optimizer in the photovoltaic system is determined to be not communicating based on the first communication signal characteristic. The DC arc fault detection scheme of the present invention achieves compatibility with both the power optimizer and arc detection functions while avoiding the impact of power optimizer communication on arc detection and reducing the false detection rate of arc detection.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic power stations, and in particular to a method, device, equipment and computer-readable storage medium for detecting DC arc faults in a photovoltaic system. Background Art

[0002] Arcing is a gas discharge phenomenon. In photovoltaic systems, once an arc fault occurs, if effective protective measures are not taken, the high temperature generated by the continuous DC arc can easily cause a fire, resulting in a major safety accident. In existing arc detection technology, the DC side signal is extracted to detect and identify the arc frequency domain characteristics to detect whether a DC arc fault has occurred. In photovoltaic systems, in order to solve the power mismatch caused by local shadowing of photovoltaic modules and module aging, a power optimizer needs to be connected in series to adjust the power output of each photovoltaic panel and improve the power generation efficiency of the string. The optimizer control device needs to exchange information with the power optimizers of each sub-node through PLC (Power Line Communication).

[0003] Since power optimizer communication requires coupling high-frequency harmonic signals through cables, and the frequency domain characteristics of arc detection are mainly extracted from the harmonic signals coupled by cables, the power optimizer's communication will inevitably affect arc detection, resulting in arc detection errors. Summary of the Invention

[0004] The main purpose of the present invention is to provide a method, device, equipment and computer-readable storage medium for detecting DC arc faults in a photovoltaic system, aiming to solve the technical problem that when the power optimizer and arc detection functions are compatible in a photovoltaic system, the power optimizer communication may cause arc detection errors.

[0005] To achieve the above object, the present invention provides a method for detecting a DC arc fault in a photovoltaic system, the method comprising the following steps:

[0006] Acquiring an AC signal on the DC side of an inverter in the photovoltaic system;

[0007] Extracting a signal feature of a preset arc detection frequency band from the DC-side AC signal as a first arc signal feature, and extracting a signal feature of a preset communication frequency band from the DC-side AC signal as a first communication signal feature;

[0008] When a suspected DC arc fault is determined to have occurred based on the first arc signal characteristic, and when it is determined based on the first communication signal characteristic that the power optimizer in the photovoltaic system is not communicating, it is determined that a real DC arc fault has occurred in the photovoltaic system.

[0009] 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, the method further includes:

[0010] Get the preset historical data set;

[0011] Calculating an arc fault determination threshold based on each second arc signal feature in the historical data set;

[0012] The first arc signal characteristic is compared with the arc fault determination threshold, and whether a suspected DC arc fault occurs is determined based on the comparison result.

[0013] Optionally, after the steps of extracting a signal feature of a preset arc detection frequency band in the DC side AC signal as the first arc signal feature, and extracting a signal feature of a preset communication frequency band in the DC side AC signal as the first communication signal feature, the step further includes:

[0014] When it is determined based on the first communication signal feature that the power optimizer in the photovoltaic system is not communicating, the first arc signal feature is added to the historical data set.

[0015] Optionally, the step of calculating an arc fault determination threshold based on each second arc signal feature in the historical data set includes:

[0016] The average value of each second arc signal feature in the historical data set is calculated, and the average value is multiplied by a preset multiple to obtain the arc fault determination threshold value.

[0017] Optionally, the photovoltaic system includes a plurality of the power optimizers, and one power optimizer is used to optimize the power of at least one photovoltaic component in the photovoltaic system;

[0018] After the step of determining that a real DC arc fault occurs in the photovoltaic system, the method further includes:

[0019] Obtaining the component voltage of the corresponding photovoltaic component from each of the power optimizers;

[0020] Get the voltage anomaly detection threshold;

[0021] If the module voltage of the photovoltaic module is less than the voltage anomaly detection threshold, it is determined that the photovoltaic module is a photovoltaic module that has a DC arc fault.

[0022] Optionally, after the steps of extracting a signal feature of a preset arc detection frequency band in the DC side AC signal as the first arc signal feature, and extracting a signal feature of a preset communication frequency band in the DC side AC signal as the first communication signal feature, the step further includes:

[0023] When it is determined based on the first arc signal characteristic that no suspected DC arc fault has occurred, or when it is determined based on the first communication signal characteristic that the power optimizer in the photovoltaic system is communicating, the step of obtaining the DC side AC signal of the inverter in the photovoltaic system is returned to execution.

[0024] Optionally, the step of extracting a signal feature of a preset arc detection frequency band in the DC-side AC signal as a first arc signal feature includes:

[0025] Performing time domain to frequency domain conversion on the DC side AC signal to obtain a frequency domain signal;

[0026] Feature extraction is performed on the signal of the preset arc detection frequency band in the frequency domain signal to obtain a first arc signal feature, wherein the feature extraction at least includes calculating one or more of the mean, root mean square value, variance and kurtosis of the signal in the preset arc detection frequency band.

[0027] 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, the method further includes:

[0028] Get the currently set arc fault detection sensitivity value;

[0029] From the arc fault determination thresholds corresponding to various preset sensitivity values, selecting the arc fault determination threshold corresponding to the currently set arc fault detection sensitivity value as the target threshold;

[0030] The first arc signal characteristic is compared with the target threshold, and whether a suspected DC arc fault occurs is determined based on the comparison result.

[0031] Optionally, after determining that a suspected DC arc fault has occurred in the photovoltaic system based on the first arc signal characteristic and determining that the power optimizer in the photovoltaic system is not communicating based on the first communication signal characteristic, the method further includes:

[0032] Controlling the inverter to shut down in case of a fault to report an arc fault;

[0033] When the preset self-starting condition is met and the duration of the inverter fault shutdown reaches a preset duration, the inverter is controlled to start, and the step of obtaining the DC side AC signal of the inverter in the photovoltaic system is performed.

[0034] To achieve the above object, the present invention further provides a photovoltaic system DC arc fault detection device, the photovoltaic system DC arc fault detection device comprising:

[0035] An acquisition module, configured to acquire an AC signal on the DC side of an inverter in the photovoltaic system;

[0036] an extraction module, 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 to extract a signal feature of a preset communication frequency band in the DC-side AC signal as a first communication signal feature;

[0037] A determination module is configured to determine that a real DC arc fault has occurred in the photovoltaic system when a suspected DC arc fault has occurred based on the first arc signal characteristic and when it is determined that the power optimizer in the photovoltaic system has not communicated based on the first communication signal characteristic.

[0038] To achieve the above-mentioned objectives, the present invention also provides a photovoltaic system DC arc fault detection device, which includes: a memory, a processor, and a photovoltaic system DC arc fault detection program stored in the memory and executable on the processor. When the photovoltaic system DC arc fault detection program is executed by the processor, the steps of the photovoltaic system DC arc fault detection method described above are implemented.

[0039] In addition, to achieve the above-mentioned purpose, the present invention also proposes a computer-readable storage medium, on which a photovoltaic system DC arc fault detection program is stored. When the photovoltaic system DC arc fault detection program is executed by a processor, the steps of the photovoltaic system DC arc fault detection method as described above are implemented.

[0040] In the present invention, the DC-side AC signal of the inverter in the photovoltaic system is obtained; the signal characteristics of a preset arc detection frequency band in the DC-side AC signal are extracted as the first arc signal characteristics, and the signal characteristics of a preset communication frequency band in the DC-side AC signal are extracted as the first communication signal characteristics. When a suspected DC arc fault is determined to have occurred based on the first arc signal characteristics, and when the power optimizer in the photovoltaic system is determined to be not communicating based on the first communication signal characteristics, a true DC arc fault is determined to have occurred in the photovoltaic system. The DC arc fault detection scheme of the present invention achieves compatibility with the power optimizer and arc detection functions while avoiding the impact of the power optimizer's communication on arc detection and reducing the false detection rate of arc detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic diagram of the hardware operating environment involved in an embodiment of the present invention;

[0042] Figure 2 This is a flow chart of a first embodiment of a method for detecting DC arc faults in a photovoltaic system according to the present invention;

[0043] Figure 3A schematic diagram of a photovoltaic system architecture according to an embodiment of the present invention;

[0044] Figure 4 A schematic diagram of a DC arc fault detection process according to an embodiment of the present invention;

[0045] Figure 5 Schematic diagram of the functional modules of a preferred embodiment of the photovoltaic system DC arc fault detection device of the present invention.

[0046] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0047] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0048] like Figure 1 As shown, Figure 1 It is a schematic diagram of the device structure of the hardware operating environment involved in the embodiment of the present invention.

[0049] It should be noted that the photovoltaic system DC arc fault detection device in the embodiment of the present invention can be a smart phone, a personal computer, a server and other devices, and is not specifically limited here.

[0050] like Figure 1 As shown, the photovoltaic system DC arc fault detection device may include: a processor 1001, such as a CPU, a network interface 1004, a user interface 1003, a memory 1005, and a communication bus 1002. 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 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.

[0051] Those skilled in the art will understand that Figure 1 The device structure shown in the figure does not constitute a limitation on the DC arc fault detection device for photovoltaic systems, and may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently.

[0052] like Figure 1As shown, the memory 1005 as a 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 and supports the operation of the photovoltaic system DC arc fault detection program and other software or programs. Figure 1 In the device shown, the user interface 1003 is mainly used to communicate data with the client; the network interface 1004 is mainly used to establish a communication connection with the server; and the processor 1001 can be used to call the photovoltaic system DC arc fault detection program stored in the memory 1005 and perform the following operations:

[0053] Acquiring an AC signal on the DC side of an inverter in the photovoltaic system;

[0054] Extracting a signal feature of a preset arc detection frequency band from the DC-side AC signal as a first arc signal feature, and extracting a signal feature of a preset communication frequency band from the DC-side AC signal as a first communication signal feature;

[0055] When a suspected DC arc fault is determined to have occurred based on the first arc signal characteristic, and when it is determined based on the first communication signal characteristic that the power optimizer in the photovoltaic system is not communicating, it is determined that a real DC arc fault has occurred in the photovoltaic system.

[0056] Furthermore, 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 also be used to call the photovoltaic system DC arc fault detection program stored in the memory 1005 and perform the following operations:

[0057] Get the preset historical data set;

[0058] Calculating an arc fault determination threshold based on each second arc signal feature in the historical data set;

[0059] The first arc signal characteristic is compared with the arc fault determination threshold, and whether a suspected DC arc fault occurs is determined based on the comparison result.

[0060] Furthermore, after 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 also be used to call the photovoltaic system DC arc fault detection program stored in the memory 1005 and perform the following operations:

[0061] When it is determined based on the first communication signal feature that the power optimizer in the photovoltaic system is not communicating, the first arc signal feature is added to the historical data set.

[0062] Furthermore, the operation of calculating the arc fault determination threshold based on each second arc signal feature in the historical data set includes:

[0063] The average value of each second arc signal feature in the historical data set is calculated, and the average value is multiplied by a preset multiple to obtain the arc fault determination threshold value.

[0064] Furthermore, the photovoltaic system includes a plurality of the power optimizers, and one power optimizer is used to optimize the power of at least one photovoltaic component in the photovoltaic system;

[0065] After determining that a real DC arc fault has occurred in the photovoltaic system, the processor 1001 may further be configured to call a photovoltaic system DC arc fault detection program stored in the memory 1005 and perform the following operations:

[0066] Obtaining the component voltage of the corresponding photovoltaic component from each of the power optimizers;

[0067] Get the voltage anomaly detection threshold;

[0068] If the module voltage of the photovoltaic module is less than the voltage anomaly detection threshold, it is determined that the photovoltaic module is a photovoltaic module that has a DC arc fault.

[0069] Furthermore, after 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 also be used to call the photovoltaic system DC arc fault detection program stored in the memory 1005 and perform the following operations:

[0070] When it is determined based on the first arc signal characteristic that no suspected DC arc fault has occurred, or when it is determined based on the first communication signal characteristic that the power optimizer in the photovoltaic system is communicating, the operation of obtaining the DC side AC signal of the inverter in the photovoltaic system is returned to execution.

[0071] Furthermore, 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 includes:

[0072] Performing time domain to frequency domain conversion on the DC side AC signal to obtain a frequency domain signal;

[0073] Feature extraction is performed on the signal of the preset arc detection frequency band in the frequency domain signal to obtain a first arc signal feature, wherein the feature extraction at least includes calculating one or more of the mean, root mean square value, variance and kurtosis of the signal in the preset arc detection frequency band.

[0074] Furthermore, 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 also be used to call the photovoltaic system DC arc fault detection program stored in the memory 1005 and perform the following operations:

[0075] Get the currently set arc fault detection sensitivity value;

[0076] From the arc fault determination thresholds corresponding to various preset sensitivity values, selecting the arc fault determination threshold corresponding to the currently set arc fault detection sensitivity value as the target threshold;

[0077] The first arc signal characteristic is compared with the target threshold, and whether a suspected DC arc fault occurs is determined based on the comparison result.

[0078] Furthermore, when it is determined based on the first arc signal characteristic that a suspected DC arc fault has occurred, and based on the first communication signal characteristic that the power optimizer in the photovoltaic system is not communicating, after determining that a real DC arc fault has occurred in the photovoltaic system, the processor 1001 may also be used to call a photovoltaic system DC arc fault detection program stored in the memory 1005 and perform the following operations:

[0079] Controlling the inverter to shut down in case of a fault to report an arc fault;

[0080] When the preset self-starting condition is met and the duration of the inverter fault shutdown reaches a preset duration, the inverter is controlled to start, and the operation of obtaining the DC side AC signal of the inverter in the photovoltaic system is performed.

[0081] Based on the above structure, various embodiments of a method for detecting a DC arc fault in a photovoltaic system are proposed.

[0082] Reference Figure 2 , Figure 2 FIG. 1 is a flow chart of a first embodiment of a method for detecting DC arc faults in a photovoltaic system according to the present invention.

[0083] The embodiment of the present invention provides an embodiment of a method for detecting a DC arc fault in a photovoltaic system. It should be noted that although a logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than here. In this embodiment, the execution subject of the method for detecting a DC arc fault in a photovoltaic system is not limited in this embodiment. For ease of description, the following embodiments are described with the arc detection device as the execution subject. In a specific implementation, the arc detection device can be located inside the photovoltaic system inverter or outside the inverter, but can establish communication with the inverter. In this embodiment, the method for detecting a DC arc fault in a photovoltaic system includes:

[0084] Step S10, obtaining a DC side AC signal of an inverter in the photovoltaic system;

[0085] In the photovoltaic system, the DC side of the inverter is connected to the photovoltaic string, and the AC side is connected to the power grid and the load, and is used to convert the DC power output from this end of the photovoltaic string into AC power, and output it to the power grid and / or the load. The optimizer control device is a device for controlling the power optimizer, which is connected in series with the inverter or is located inside the inverter (the following explanation is based on the example of the optimizer control device being located inside the inverter). The power optimizer optimizes the power of at least one photovoltaic component, and the power optimizer and the photovoltaic component it optimizes can be regarded as one (the specific connection method is not limited in this embodiment); each photovoltaic component is connected in series in sequence through the positive and negative poles of the power optimizer to form a photovoltaic string, and the positive and negative poles of the photovoltaic string are connected to the positive and negative poles of the inverter DC side. When there are multiple photovoltaic strings, each photovoltaic string is connected to the inverter respectively, that is, each photovoltaic string is in a parallel relationship. During the operation of the photovoltaic system, the optimizer control device communicates with the power optimizer regularly or irregularly. In this embodiment, there is no restriction on the communication frequency between the optimizer control device and the power optimizer. Figure 3 As shown, a schematic diagram of the architecture of a photovoltaic system is shown, but it is only a schematic diagram and should not be understood as bringing any limitation to the architecture, function and scope of use of the photovoltaic system in this embodiment.

[0086] When DC arc fault detection is required, the arc detection device acquires the AC signal on the DC side of the inverter in the photovoltaic system. Because the DC side current signal also contains some AC signals, the acquired DC side current signal is referred to as the DC side AC signal.

[0087] Step S20, extracting a signal feature of a preset arc detection frequency band in the DC-side AC signal as a first arc signal feature, and extracting a signal feature of a preset communication frequency band in the DC-side AC signal as a first communication signal feature;

[0088] After obtaining the DC side AC signal, the arc detection device can extract the signal characteristics of the preset arc detection frequency band in the DC side AC signal, wherein the preset arc detection frequency band is a pre-set frequency band, which is considered to be the frequency band where the arc signal characteristics are located, so the extracted signal characteristics are called arc signal characteristics (hereinafter referred to as the first arc signal characteristics for distinction).

[0089] The arc detection device can also extract signal characteristics of a preset communication frequency band in the DC side AC signal, wherein the preset communication frequency band is the frequency band used by the optimizer control device to communicate with the power optimizer. Depending on the equipment and communication method used, the preset communication frequency band may be different. The extracted signal characteristics are called communication signal characteristics (hereinafter referred to as the first communication signal characteristics for distinction).

[0090] The method for extracting the first arc signal feature and the first communication signal feature is not limited in this embodiment, and a commonly used frequency domain signal feature extraction method can be used.

[0091] It should be noted that there may or may not be overlap between the preset arc detection frequency band and the preset communication frequency band. In the case of overlap, the optimizer control device will definitely affect the arc detection when communicating with the power optimizer. In the case of no overlap, the closer the preset arc detection frequency band is to the preset communication frequency band, the greater the impact on arc detection when the optimizer control device communicates with the power optimizer.

[0092] Step S30 , when it is determined based on the first arc signal characteristic that a suspected DC arc fault has occurred, and based on the first communication signal characteristic that the power optimizer in the photovoltaic system has not communicated, it is determined that a real DC arc fault has occurred in the photovoltaic system.

[0093] After extracting the first arc signal signature, the arc detection device can determine whether a suspected DC arc fault exists based on the first arc signal signature. It should be noted that because communication between the optimizer control device and the power optimizer will affect the results of DC arc fault detection based on the arc signal signature, even if a DC arc fault is determined based on the first arc signal signature, the result may not be accurate. Therefore, determining whether a DC arc fault exists based on the first arc signal signature is referred to as "determining whether a suspected DC arc fault exists based on the first arc signal signature."

[0094] The specific method for determining whether there is a suspected DC arc fault based on the first arc signal characteristics is not limited in this embodiment. For example, it can be compared with a pre-set fixed threshold or an adaptive threshold, and whether there is a suspected DC arc fault can be determined based on the comparison result.

[0095] After extracting the first communication signal characteristic, the arc detection device can determine whether the power optimizer is communicating based on the first communication signal characteristic. It should be understood that the power optimizer communicating refers to communicating with the optimizer control device. The specific method for determining whether the power optimizer is communicating based on the first communication signal characteristic is not limited in this embodiment. For example, the method can be used to compare the first communication signal characteristic with a preset fixed threshold or an adaptive threshold, and determine whether the power optimizer is communicating based on the comparison result.

[0096] When a suspected DC arc fault is determined to have occurred based on the first arc signal characteristic and the power optimizer is determined to have not communicated based on the first communication signal characteristic, it can be determined that the communication between the optimizer control device and the power optimizer is not affected at this time, and the DC arc fault determined to have occurred based on the first arc signal characteristic is credible, that is, the arc detection device can determine that a real DC arc fault has occurred in the photovoltaic system.

[0097] Furthermore, in one embodiment, after determining that a true DC arc fault has occurred in the photovoltaic system, the arc detection device can take corresponding measures to avoid the impact of the DC arc fault. The specific measures taken are not limited in this embodiment, and for example, an alarm device can be controlled to sound an alarm.

[0098] Furthermore, in one embodiment, the arc detection device may first determine whether a suspected DC arc fault has occurred based on the first arc signal characteristic. If a suspected DC arc fault has occurred, the arc detection device may then determine whether the power optimizer is communicating based on the first communication signal characteristic. If a suspected DC arc fault has not occurred, the detection of whether the power optimizer is communicating may be discontinued, and it may be determined that no actual DC arc fault has occurred in the photovoltaic system. Alternatively, in another embodiment, when only a true DC fault needs to be detected, the arc detection device may first determine whether the power optimizer is communicating based on the first communication signal characteristic. If the power optimizer is not communicating, the arc detection device may then determine whether a suspected DC arc fault has occurred based on the first arc signal characteristic. If the power optimizer is communicating, the detection of whether a suspected DC arc fault has occurred may be discontinued.

[0099] Furthermore, in one embodiment, when a suspected DC arc fault is determined to have occurred based on the first arc signal characteristic, and when the power optimizer is determined to be communicating based on the first communication signal characteristic, the arc detection device can determine that a suspected DC arc fault has occurred in the photovoltaic system. This means, to a technician, that a DC arc fault may have occurred in the photovoltaic system. When a suspected DC arc fault is determined to have occurred, the arc detection device can also, as needed, configure corresponding countermeasures. These countermeasures can be configured to be different from, or lower in level than, countermeasures for a true DC arc fault, as needed. For example, when a suspected DC arc fault is determined to have occurred, the arc detection device can output an alarm. When a true DC arc fault is determined to have occurred, the arc detection device can directly shut down the inverter to prevent damage caused by the arc fault.

[0100] Furthermore, in one embodiment, after step S20, the following steps are further included:

[0101] In step a, when it is determined based on the first arc signal characteristic that no suspected DC arc fault has occurred, or when it is determined based on the first communication signal characteristic that the power optimizer in the photovoltaic system is communicating, the process returns to step S10.

[0102] When it is determined based on the first arc signal characteristic that a suspected DC arc fault has not occurred, or when it is determined based on the first communication signal characteristic that the power optimizer is communicating, it cannot be confirmed that a true DC arc fault has occurred in the photovoltaic system. To avoid false detection (determining that a true DC arc fault has occurred when it has not actually occurred), the arc detection device may, as needed, not take corresponding countermeasures and directly return to executing the operation of obtaining the DC-side AC signal for arc signal feature extraction and communication signal feature extraction. It is understandable that the communication time between the power optimizer and the optimizer control device is generally very short. When it is determined based on the first arc signal characteristic that a suspected DC arc fault has occurred and based on the first communication signal characteristic that the power optimizer is communicating, even if no corresponding countermeasures are taken, the next communication gap will soon arrive. Therefore, if a DC arc fault has actually occurred, it can still be detected in the next communication gap, thereby avoiding the adverse effects of the DC arc fault.

[0103] Furthermore, in one embodiment, 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 in step S20 includes:

[0104] Step S201, performing time domain to frequency domain conversion on the DC side AC signal to obtain a frequency domain signal;

[0105] In this embodiment, a method for extracting the characteristics of the first arc signal in the DC side AC signal is proposed. Specifically, the arc detection device can first convert the DC side AC signal from the time domain to the frequency domain to obtain a frequency domain signal. It can be understood that the acquired DC side AC signal is a signal composed of current values ​​at different times and belongs to a signal in the time domain. In order to extract the characteristics of the signal in the preset arc detection frequency band in the signal, the DC side AC signal can be first converted from the time domain to the frequency domain. The converted signal is called a frequency domain signal. In this embodiment, there is no limitation on the method used to convert the signal from the time domain to the frequency domain. For example, a fast Fourier transform method can be used.

[0106] Step S202: performing feature extraction on the signal of the preset arc detection frequency band in the frequency domain signal to obtain a first arc signal feature, wherein the feature extraction at least includes calculating one or more of the mean, root mean square value, variance and kurtosis of the signal in the preset arc detection frequency band.

[0107] After converting the frequency domain signal to obtain the frequency domain signal, the signal within the preset arc detection frequency band can be extracted from the frequency domain signal, and feature extraction is performed on this portion of the signal to obtain the first arc signal feature. Depending on specific needs, feature extraction can include at least calculating one or more of the mean, root mean square value, variance, and kurtosis of the signal within the preset arc detection frequency band. The methods for calculating the mean, root mean square value, variance, and kurtosis are not described in detail here. It is understood that in other embodiments, feature extraction can also include other feature extraction methods.

[0108] Furthermore, in one embodiment, the method for extracting the first communication signal feature in the DC side AC signal can also be to first convert the signal from the time domain to the frequency domain, then extract the signal in the preset communication detection frequency band from the frequency domain signal, and perform feature extraction on this part of the signal to obtain the first communication signal feature. The feature extraction can at least include calculating one or more of the mean, root mean square value, variance and kurtosis of the signal in the preset arc detection frequency band.

[0109] In this embodiment, the DC-side AC signal of the inverter in the photovoltaic system is obtained; signal characteristics of a preset arc detection frequency band in the DC-side AC signal are extracted as first arc signal characteristics, and signal characteristics of a preset communication frequency band in the DC-side AC signal are extracted as first communication signal characteristics. When a suspected DC arc fault is determined to have occurred based on the first arc signal characteristics, and when the power optimizer in the photovoltaic system is determined to be non-communicating based on the first communication signal characteristics, a true DC arc fault is determined to have occurred in the photovoltaic system. The DC arc fault detection scheme in this embodiment achieves compatibility with both the power optimizer and arc detection functions while avoiding the impact of power optimizer communication on arc detection and reducing the false detection rate of arc detection.

[0110] Furthermore, based on the first embodiment described above, a second embodiment of the method for detecting DC arc faults in a photovoltaic system of the present invention is proposed. In this embodiment, after the step S20 of extracting the signal characteristics of the preset arc detection frequency band in the DC-side AC signal as the first arc signal characteristics, the method further includes:

[0111] Step S40, obtaining a preset historical data set;

[0112] In this embodiment, a method for detecting suspected DC arc faults based on an adaptive threshold is proposed. The adaptive threshold is adaptively determined based on historical data, used to compare the threshold with the first arc signal signature, thereby improving arc detection accuracy. Specifically, a historical dataset can be used to store arc signal signatures extracted from DC-side AC signals over a period of time. This is referred to as the second arc signal signature to distinguish it from the first arc signal signature. In this embodiment, there is no restriction on the length of time arc signal signatures stored in the historical dataset; this can be set as needed.

[0113] Step S50, calculating an arc fault determination threshold based on each second arc signal feature in the historical data set;

[0114] When it is necessary to determine whether a suspected DC arc fault has occurred based on the first arc signal characteristics, the arc detection device can first calculate the arc fault determination threshold based on each second arc signal characteristic in the historical data set. The arc fault determination threshold is an adaptively determined threshold.

[0115] The method for calculating the arc fault determination threshold based on each second arc signal characteristic is not limited in this embodiment. For example, each second arc signal characteristic can be averaged or weighted averaged, and the specific method can be set as needed. When the second arc signal characteristic includes multiple characteristic values, such as four types of characteristic values: mean, root mean square value, variance, and kurtosis, the arc detection device can calculate the arc fault determination threshold corresponding to the characteristic value of the same type based on the characteristic value of each second arc signal characteristic. In this way, the arc fault determination threshold corresponding to each type of characteristic value can be ultimately obtained.

[0116] Step S60: Compare the first arc signal characteristic with the arc fault determination threshold, and determine whether a suspected DC arc fault occurs based on the comparison result.

[0117] After obtaining the arc fault determination threshold, the arc detection device can compare the first arc signal characteristic with the arc fault determination threshold to obtain a comparison result. Based on the comparison result, it can determine whether a suspected DC arc fault has occurred. The comparison result reflects the magnitude relationship between the first arc signal characteristic and the arc fault determination threshold. The comparison result that determines the occurrence of a suspected DC arc fault can be configured as needed and is not limited in this embodiment. For example, in one embodiment, a suspected DC arc fault can be determined when the first arc signal characteristic is greater than the arc fault determination threshold. In a specific embodiment, when the first arc signal characteristic includes multiple types of characteristic values, each type of characteristic value can be compared with the corresponding type of arc fault determination threshold.

[0118] Furthermore, in one embodiment, after step S20, the following steps are further included:

[0119] Step S70 : When it is determined based on the first communication signal characteristic that the power optimizer in the photovoltaic system is not communicating, the first arc signal characteristic is added to the historical data set.

[0120] In order to avoid adding the arc signal characteristics extracted based on the DC side AC signal affected by communication interference to the historical data set, thereby affecting the calculation accuracy of the adaptive threshold and further affecting the accuracy of arc fault detection, in this embodiment, the arc detection device can add the first arc signal characteristics to the historical data set only when it determines that the power optimizer in the photovoltaic system is not communicating based on the first communication signal characteristics.

[0121] Furthermore, in one embodiment, step S50 includes:

[0122] Step S501 : calculating the mean value of each second arc signal feature in the historical data set, and multiplying the mean value by a preset multiple to obtain the arc fault determination threshold value.

[0123] In this embodiment, a method for calculating an arc fault determination threshold is proposed. Specifically, the arc detection device may first calculate the mean of each second arc signal characteristic in a historical data set, and then multiply the mean by a preset multiple to obtain the arc fault determination threshold. When a suspected DC arc fault is determined to have occurred when the first arc signal characteristic is less than the arc fault determination threshold, the preset multiple is generally set to be greater than 0 and less than 1 to avoid false detections caused by small fluctuations in the DC-side AC signal, even when no DC arc fault has actually occurred.

[0124] Furthermore, based on the first and / or second embodiments described above, a third embodiment of the method for detecting DC arc faults in a photovoltaic system of the present invention is proposed. In this embodiment, the photovoltaic system includes multiple power optimizers, one of which is used to optimize the power of at least one photovoltaic module in the photovoltaic system. After step S30, the method further includes:

[0125] Step A10, obtaining the component voltage of the corresponding photovoltaic component from each of the power optimizers;

[0126] In this embodiment, the power optimizer is used to obtain the voltage of the optimized photovoltaic module (hereinafter referred to as the module voltage) for locating the photovoltaic module where the DC arc fault occurs.

[0127] Specifically, the power optimizer can detect the component voltage of the photovoltaic component optimized by the detector. By utilizing the communication between the power optimizer and the optimizer control device, the power optimizer can send the component voltage of the photovoltaic component it optimizes to the optimizer control device, and the arc detection device can obtain the component voltage of the photovoltaic component from the optimizer control device.

[0128] Step A20, obtaining a voltage anomaly detection threshold;

[0129] Step A30: If the module voltage of the photovoltaic module is less than the voltage anomaly detection threshold, it is determined that the photovoltaic module is a photovoltaic module that has a DC arc fault.

[0130] When a DC arc fault occurs in a photovoltaic module, damaging some of the module's cells, the module's voltage decreases accordingly. The voltage anomaly detection threshold is used to determine whether a DC arc fault has occurred in the photovoltaic module. When the module voltage is less than the voltage anomaly detection threshold, a DC arc fault is determined. The voltage anomaly detection threshold can be a fixed threshold set in advance as needed, or it can be adaptively determined, and is not limited in this embodiment.

[0131] In this embodiment, after determining that a real DC arc fault has occurred, the component voltage of the photovoltaic module is obtained from the power optimizer, and the component voltage is compared with the voltage anomaly detection threshold to locate the photovoltaic module where the DC arc fault has occurred. This allows technicians to clearly understand the location of the photovoltaic module where the DC arc fault has occurred, and then perform maintenance management, thereby improving the efficiency of DC arc fault troubleshooting.

[0132] Furthermore, in one embodiment, a method for obtaining a voltage anomaly detection threshold is proposed. Specifically, the obtained component voltages of each photovoltaic module can be averaged and multiplied by a preset multiple (hereinafter referred to as the first preset multiple for distinction) to obtain the voltage anomaly detection threshold. The first preset multiple is greater than 0 and less than 1, and the specific value can be set as needed. A larger setting results in a lower missed detection rate, but false detections may occur. A lower setting results in a lower false detection rate, but missed detections may occur.

[0133] It should be noted that when no DC arc fault occurs, the component voltages of each photovoltaic module are almost the same. When a DC arc fault occurs in a photovoltaic module, its component voltage will be lower than the average level of the component voltages of each photovoltaic module. Therefore, by multiplying the average value of the component voltages of each photovoltaic module by a first preset multiple as the voltage anomaly detection threshold, and then comparing the component voltage of the photovoltaic module with the voltage anomaly detection threshold, it is possible to detect whether a DC arc fault has occurred in the photovoltaic module.

[0134] Furthermore, in one embodiment, another method for obtaining a voltage anomaly detection threshold is proposed. Specifically, the arc detection device can pre-acquire the component voltage of each photovoltaic module when no DC arc fault occurs in the photovoltaic system (hereinafter referred to as the historical component voltage). For each photovoltaic module, the historical component voltage of the photovoltaic module when no DC arc fault occurs is used as the voltage anomaly detection threshold corresponding to the photovoltaic module. The obtained component voltage of the photovoltaic module is compared with the voltage anomaly detection threshold corresponding to the photovoltaic module. If it is less than the corresponding voltage anomaly detection threshold, the arc detection device can determine that a DC arc fault has occurred in the photovoltaic module. It is understandable that when a DC arc fault occurs in a photovoltaic module, its component voltage will be lower than its voltage level when no DC arc fault occurs. Therefore, by using the component voltage of the photovoltaic module when no DC arc fault occurs as the voltage anomaly detection threshold, and then comparing the component voltage of the photovoltaic module with the voltage anomaly detection threshold, it is possible to detect whether a DC arc fault has occurred in the photovoltaic module.

[0135] Furthermore, in one embodiment, 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 in step S20, the method further includes:

[0136] Step A40, obtaining the currently set arc fault detection sensitivity value;

[0137] In this embodiment, whether a DC arc fault occurs can be determined by comparing the first arc signal characteristic with a preset fixed threshold. However, in order to improve the flexibility of detection, arc fault judgment thresholds corresponding to different sensitivities can be set in advance to meet the sensitivity requirements of different users for arc detection.

[0138] The arc detection device can obtain the currently set arc fault detection sensitivity. The arc detection device can provide a user-input method for arc fault detection sensitivity, allowing the user to adjust the arc detection sensitivity as needed. A higher sensitivity indicates a lower missed detection rate, but may result in false detections. A lower sensitivity indicates a lower false detection rate, but may result in missed detections.

[0139] Step A50, selecting, from among the preset arc fault determination thresholds corresponding to various sensitivity values, an arc fault determination threshold corresponding to the currently set arc fault detection sensitivity value as a target threshold;

[0140] The arc detection device selects, from among various preset arc fault detection threshold values ​​corresponding to various sensitivity values, an arc fault detection threshold value corresponding to the currently set arc fault detection sensitivity value as the threshold value for comparison with the currently extracted first arc signal feature, hereinafter referred to as the target threshold value for purposes of distinction. In one embodiment, when a suspected DC arc fault is determined to have occurred when the first arc signal feature is less than the arc fault detection threshold value, the arc fault detection threshold value may be set higher for lower sensitivity values.

[0141] Step A60: Compare the first arc signal characteristic with the target threshold, and determine whether a suspected DC arc fault occurs based on the comparison result.

[0142] After determining the target threshold, the arc detection device can compare the first arc signal characteristic with the target threshold and, based on the comparison result, determine whether a suspected DC arc fault has occurred. The comparison result reflects the magnitude relationship between the first arc signal characteristic and the target threshold. The comparison result that determines the occurrence of a suspected DC arc fault can be configured as needed and is not limited in this embodiment. For example, in one embodiment, a suspected DC arc fault can be determined when the first arc signal characteristic is greater than the target threshold. In specific embodiments, when the first arc signal characteristic includes multiple types of characteristic values, each type of characteristic value can be compared with the corresponding target threshold.

[0143] Furthermore, in one embodiment, after step S30, the following steps are further included:

[0144] Step A70, controlling the inverter to shut down due to a fault to report an arc fault;

[0145] This embodiment proposes a response measure for determining a true DC arc fault in a photovoltaic system. Specifically, upon determining a true DC arc fault, the arc detection device can control the inverter to shut down, reporting the arc fault via a fault-stop mechanism. In specific embodiments, the inverter shutdown mechanism can specifically stop converting DC power to AC power, while other functions can continue to operate.

[0146] Step A80, when the preset self-starting condition is met and the duration of the inverter fault shutdown reaches a preset duration, control the inverter to start up and execute the step of obtaining the DC side AC signal of the inverter in the photovoltaic system.

[0147] Furthermore, in one embodiment, after the inverter shuts down due to a fault, the arc detection device can, if preset self-start conditions are met, time the inverter shutdown duration. When the preset duration is reached, the inverter can be controlled to restart. After the inverter is controlled to restart, the arc detection device continues to acquire the DC-side AC signal of the photovoltaic system inverter and continue to detect DC arc faults. The preset self-start conditions can be set as needed. For example, the user can set self-start to be enabled. Alternatively, if the inverter shuts down due to a fault N times in a day, self-start is disabled, and self-start is enabled within N times. N can be set as needed, for example, to 5 times.

[0148] Furthermore, in one embodiment, the process of DC arc fault detection can be as follows: Figure 4 shown.

[0149] The first step is to initialize the parameters after the inverter is powered on, and preset the arc detection frequency band [F1-F2] and the optimizer communication frequency band [f1-f2];

[0150] In the second step, during grid-connected operation, the arc detection device collects the AC signal on the DC side of the inverter in real time and performs fast Fourier transform (FFT) analysis;

[0151] The third step is to extract the arc signal characteristics of the frequency band [F1~F2] ( Figure 4 The arc characteristics are used in the figure), including but not limited to at least one signal feature such as mean, root mean square value, variance, kurtosis, etc.; extract the communication signal features of the frequency band [f1~f2] ( Figure 4 (represented by communication characteristics), including but not limited to at least one signal characteristic such as mean, root mean square value, variance, kurtosis, etc.;

[0152] The fourth step is to compare the arc signal characteristics with the preset threshold or adaptive threshold to determine whether an arc occurs; if an arc occurs, execute the fifth step; if no arc occurs, execute the second step;

[0153] Step 5: Compare the communication signal characteristics with the preset threshold or adaptive threshold to determine whether PLC communication is in progress. If the optimizer is in PLC communication, execute step 2. If the optimizer is not in communication, execute step 6.

[0154] Step 6: The inverter shuts down due to fault and reports an arc fault.

[0155] When using adaptive threshold, the threshold is determined by historical data ( Figure 4 The optimizer will have a greater impact on the communication frequency band and its nearby frequency points when performing PLC communication, causing wide-range frequency domain signal changes. Therefore, the arc signal characteristics and communication signal characteristics obtained during PLC communication can be excluded from the historical data to exclude the adaptive threshold changes caused by PLC communication.

[0156] This implementation combines the power optimizer and arc detection functions. By adding the optimizer's PLC communication frequency band to the arc detection device to identify whether the optimizer is communicating, it eliminates interference from PLC communication on arc detection and achieves compatibility between the two functions. This eliminates the false alarm effects of optimizer PLC communication on arc detection and eliminates adaptive threshold changes caused by PLC communication, improving arc detection capabilities and ensuring efficient, safe, and stable operation of the power plant system.

[0157] In addition, the embodiment of the present invention also provides a photovoltaic system DC arc fault detection device, referring to Figure 5 , the photovoltaic system DC arc fault detection device includes:

[0158] An acquisition module 10 is configured to acquire an AC signal on the DC side of an inverter in the photovoltaic system;

[0159] an extraction module 20, configured to extract a signal feature of a preset arc detection frequency band from the DC-side AC signal as a first arc signal feature, and to extract a signal feature of a preset communication frequency band from the DC-side AC signal as a first communication signal feature;

[0160] The determination module 30 is configured to determine that a real DC arc fault has occurred in the photovoltaic system when a suspected DC arc fault has occurred based on the first arc signal characteristic and when it is determined that the power optimizer in the photovoltaic system has not communicated based on the first communication signal characteristic.

[0161] Furthermore, the acquisition module 10 is also used to acquire a preset historical data set;

[0162] The photovoltaic system DC arc fault detection device further includes:

[0163] a calculation module, configured to calculate an arc fault determination threshold based on each second arc signal feature in the historical data set;

[0164] The first comparison module is configured to compare the first arc signal characteristic with the arc fault determination threshold, and determine whether a suspected DC arc fault occurs based on the comparison result.

[0165] Furthermore, the photovoltaic system DC arc fault detection device further includes:

[0166] An adding module is configured to add the first arc signal feature to the historical data set when it is determined based on the first communication signal feature that the power optimizer in the photovoltaic system is not communicating.

[0167] Furthermore, the calculation module is also used for:

[0168] The average value of each second arc signal feature in the historical data set is calculated, and the average value is multiplied by a preset multiple to obtain the arc fault determination threshold value.

[0169] Furthermore, the photovoltaic system includes a plurality of the power optimizers, and one power optimizer is used to optimize the power of at least one photovoltaic component in the photovoltaic system;

[0170] The acquisition module 10 is further configured to: acquire the component voltage of the corresponding photovoltaic component from each power optimizer; and acquire a voltage anomaly detection threshold;

[0171] The determining module 30 is further configured to determine that the photovoltaic assembly is a photovoltaic assembly having a DC arc fault if the assembly voltage of the photovoltaic assembly is less than the voltage anomaly detection threshold.

[0172] Furthermore, the acquisition module 10 is further configured to:

[0173] When it is determined based on the first arc signal characteristic that no suspected DC arc fault has occurred, or when it is determined based on the first communication signal characteristic that the power optimizer in the photovoltaic system is communicating, the operation of obtaining the DC side AC signal of the inverter in the photovoltaic system is returned to execution.

[0174] Furthermore, the extraction module 20 is further configured to:

[0175] Performing time domain to frequency domain conversion on the DC side AC signal to obtain a frequency domain signal;

[0176] Feature extraction is performed on the signal of the preset arc detection frequency band in the frequency domain signal to obtain a first arc signal feature, wherein the feature extraction at least includes calculating one or more of the mean, root mean square value, variance and kurtosis of the signal in the preset arc detection frequency band.

[0177] Furthermore, the acquisition module 10 is further configured to acquire a currently set arc fault detection sensitivity value;

[0178] The photovoltaic system DC arc fault detection device further includes:

[0179] a selection module, configured to select, from among the arc fault determination thresholds corresponding to various preset sensitivity values, an arc fault determination threshold corresponding to the currently set arc fault detection sensitivity value as a target threshold;

[0180] The second comparison module is configured to compare the first arc signal characteristic with the target threshold value, and determine whether a suspected DC arc fault occurs based on the comparison result.

[0181] Furthermore, the photovoltaic system DC arc fault detection device further includes:

[0182] A control module is used to control the inverter to shut down due to a fault to report an arc fault; when a preset self-start condition is met and the duration of the inverter shutdown due to a fault reaches a preset duration, control the inverter to start up and execute the operation of obtaining the DC side AC signal of the inverter in the photovoltaic system.

[0183] The expanded content of the specific implementation of the photovoltaic system DC arc fault detection device of the present invention is basically the same as the embodiments of the photovoltaic system DC arc fault detection method described above, and will not be elaborated here.

[0184] In addition, an embodiment of the present invention further proposes a computer-readable storage medium, on which a photovoltaic system DC arc fault detection program is stored. When the photovoltaic system DC arc fault detection program is executed by a processor, the steps of the photovoltaic system DC arc fault detection method described below are implemented.

[0185] The various embodiments of the photovoltaic system DC arc fault detection device and the computer-readable storage medium of the present invention may refer to the various embodiments of the photovoltaic system DC arc fault detection method of the present invention, and will not be repeated here.

[0186] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0187] The serial numbers of the above embodiments of the present invention are for description only and do not represent the advantages or disadvantages of the embodiments.

[0188] Through the description of the above embodiments, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus the necessary general hardware platform, and of course can also be implemented by hardware, but in many cases the former is a better embodiment. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can 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 a number of instructions for enabling a terminal device (which can be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in each embodiment of the present invention.

[0189] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for detecting DC arc faults in a photovoltaic system, characterized in that: The photovoltaic system DC arc fault detection method comprises the following steps: Acquiring an AC signal on the DC side of an inverter in the photovoltaic system; Extracting a signal feature of a preset arc detection frequency band from the DC-side AC signal as a first arc signal feature, and extracting a signal feature of a preset communication frequency band from the DC-side AC signal as a first communication signal feature; When it is determined based on the first arc signal characteristic that a suspected DC arc fault has occurred, and based on the first communication signal characteristic that the power optimizer in the photovoltaic system has not communicated, it is determined that a real DC arc fault has occurred in the photovoltaic system; The photovoltaic system includes a plurality of power optimizers, one of the power optimizers being used to optimize the power of at least one photovoltaic component in the photovoltaic system; After the step of determining that a real DC arc fault occurs in the photovoltaic system, the method further includes: Obtaining the component voltage of the corresponding photovoltaic component from each of the power optimizers; Get the voltage anomaly detection threshold; If the module voltage of the photovoltaic module is less than the voltage anomaly detection threshold, it is determined that the photovoltaic module is a photovoltaic module that has a DC arc fault.

2. The photovoltaic system DC arc fault detection method according to claim 1, characterized in that: 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 includes: Get the preset historical data set; Calculating an arc fault determination threshold based on each second arc signal feature in the historical data set; The first arc signal characteristic is compared with the arc fault determination threshold, and whether a suspected DC arc fault occurs is determined based on the comparison result.

3. The photovoltaic system DC arc fault detection method according to claim 2, characterized in that: After the steps 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: When it is determined based on the first communication signal feature that the power optimizer in the photovoltaic system is not communicating, the first arc signal feature is added to the historical data set.

4. The photovoltaic system DC arc fault detection method according to claim 2, wherein: The step of calculating the arc fault determination threshold based on each second arc signal feature in the historical data set includes: The average value of each second arc signal feature in the historical data set is calculated, and the average value is multiplied by a preset multiple to obtain the arc fault determination threshold value.

5. The photovoltaic system DC arc fault detection method according to claim 1, wherein: After the steps 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: When it is determined based on the first arc signal characteristic that no suspected DC arc fault has occurred, or when it is determined based on the first communication signal characteristic that the power optimizer in the photovoltaic system is communicating, the step of obtaining the DC side AC signal of the inverter in the photovoltaic system is returned to execution.

6. The photovoltaic system DC arc fault detection method according to claim 1, wherein: 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 comprises: Performing time domain to frequency domain conversion on the DC side AC signal to obtain a frequency domain signal; Feature extraction is performed on the signal of the preset arc detection frequency band in the frequency domain signal to obtain a first arc signal feature, wherein the feature extraction at least includes calculating one or more of the mean, root mean square value, variance and kurtosis of the signal in the preset arc detection frequency band.

7. The photovoltaic system DC arc fault detection method 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 includes: Get the currently set arc fault detection sensitivity value; From the arc fault determination thresholds corresponding to various preset sensitivity values, selecting the arc fault determination threshold corresponding to the currently set arc fault detection sensitivity value as the target threshold; The first arc signal characteristic is compared with the target threshold, and whether a suspected DC arc fault occurs is determined based on the comparison result.

8. The photovoltaic system DC arc fault detection method according to any one of claims 1 to 7, characterized in that: After determining that a suspected DC arc fault has occurred in the photovoltaic system based on the first arc signal characteristic and that the power optimizer in the photovoltaic system is not communicating based on the first communication signal characteristic, the method further includes: Controlling the inverter to shut down in case of a fault to report an arc fault; When the preset self-starting condition is met and the duration of the inverter fault shutdown reaches a preset duration, the inverter is controlled to start, and the step of obtaining the DC side AC signal of the inverter in the photovoltaic system is performed.

9. A photovoltaic system DC arc fault detection device, characterized in that: The photovoltaic system DC arc fault detection device comprises: An acquisition module, configured to acquire an AC signal on the DC side of an inverter in the photovoltaic system; an extraction module, 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 to extract a signal feature of a preset communication frequency band in the DC-side AC signal as a first communication signal feature; a determination module, configured to determine that a real DC arc fault has occurred in the photovoltaic system when it is determined based on the first arc signal characteristic that a suspected DC arc fault has occurred and when it is determined based on the first communication signal characteristic that the power optimizer in the photovoltaic system has not communicated; The photovoltaic system includes a plurality of power optimizers, one of the power optimizers being used to optimize the power of at least one photovoltaic component in the photovoltaic system; The acquisition module is further configured to: acquire the component voltage of the corresponding photovoltaic component from each of the power optimizers; and acquire a voltage anomaly detection threshold; The determination module is further configured to determine that the photovoltaic assembly is a photovoltaic assembly having a DC arc fault if the assembly voltage of the photovoltaic assembly is less than the voltage anomaly detection threshold.

10. A photovoltaic system DC arc fault detection device, characterized in that: The photovoltaic system DC arc fault detection device includes: a memory, a processor, and a photovoltaic system DC arc fault detection program stored in the memory and executable on the processor. When the photovoltaic system DC arc fault detection program is executed by the processor, the steps of the photovoltaic system DC arc fault detection method according to any one of claims 1 to 8 are implemented.

11. A computer-readable storage medium, characterized in that The computer-readable storage medium stores 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 8.

Images