A Distributed Arc Detection Method

Abstract

This invention discloses a distributed arc detection method for detecting whether arcing has occurred in the connection lines between photovoltaic panels in a photovoltaic array. The detection method includes the following steps: pre-deploying arc detection modules in a distributed manner within the photovoltaic array; if one arc detection module detects an arcing signal, then the following steps are performed: obtaining the detection results of the other arc detection modules for the arcing signal; if none of the other arc detection modules detect an arcing signal, then ignoring the arcing signal detected by one of the arc detection modules. This invention utilizes the distributed arc detection modules in the photovoltaic array to reduce the impact of cable impedance and the distributed capacitance of the photovoltaic panels to ground on the attenuation of the arcing signal, and reduces interference from inverter machine noise, making it less likely to cause missed / false arcing detection; furthermore, by identifying the ID of the arc detection module with the strongest arcing characteristics, the location of the arcing fault is pinpointed, reducing the work of troubleshooting the fault location.

Description

[0001] Related information

[0002] This application is a divisional application of the invention patent application filed on December 28, 2021, with application number 2021116152540 and invention title "Distributed Arc Detection System, Photovoltaic System Having the Same and Arc Detection Method". Technical Field

[0003] This invention relates to the field of power electronics, and more particularly to a distributed arc detection method. Background Technology

[0004] With the development of photovoltaic power generation technology, the power output of a single photovoltaic inverter is constantly increasing, and the number of photovoltaic modules connected to the inverter is also increasing. Consequently, the number of connection points is also increasing, leading to a greater risk of DC arcing faults. Simultaneously, as the number of photovoltaic modules increases, the cable length also increases, and the line impedance between the arcing location and the arcing sensor also increases. This weakens the strength of the arc characteristic signal when an arc occurs, increasing the risk of missed arcing detection. Furthermore, as the machine power increases, the internal noise level may also increase. Since currently used arc detection devices are mostly integrated inside the inverter or concentrated near the inverter (see Chinese Patent No. CN207475487U), the closer the arc detection device is to the inverter, the stronger the interference from machine noise, potentially leading to false triggering of arcing detection, causing unnecessary shutdowns and affecting power generation.

[0005] On the other hand, as the power of photovoltaic inverters increases, if the inverter issues an arcing alarm but does not have an arc fault location function, a large number of connection points need to be checked one by one, which is a very time-consuming and labor-intensive task.

[0006] Currently, arcing detection devices are mostly located near the inverter. As the number of detection channels increases, factors such as noise interference and MCU computing power are affecting the accuracy and stability of arcing detection. Summary of the Invention

[0007] The purpose of this invention is to provide a distributed arc detection method, which reduces the difficulty of detecting DC arc faults in increasingly powerful photovoltaic systems by using a distributed arc detection device, thereby improving the detection accuracy and reducing the false alarm rate.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A distributed arc detection system includes a main control module and multiple arc detection modules distributed in a photovoltaic array. Each arc detection module includes:

[0010] An electrical signal detector is configured to detect electrical signals at the location of the arc detection module;

[0011] An arc fault detector is configured to calculate arc characteristic signal values ​​based on the electrical signals detected by a corresponding electrical signal detector.

[0012] A communication circuit unit is configured to enable communication between the corresponding arc fault detector and the main control module.

[0013] Furthermore, the communication circuit unit of the arc detection module communicates bidirectionally with the main control module;

[0014] In response to the arcing prediction result of one of the arc fault detectors, the main control module requests the arcing characteristic signal values ​​calculated by the other arc fault detectors. If the arcing characteristic signal values ​​of the other arc fault detectors are all lower than the preset threshold, the arcing prediction result is determined to be a misjudgment result.

[0015] Furthermore, if the arcing characteristic signal value of at least one of the other arc fault detectors reaches the preset threshold, the main control module triggers the photovoltaic module shutdown device of the photovoltaic array.

[0016] Furthermore, if the arcing characteristic signal value of at least one of the other arc fault detectors reaches the preset threshold, the main control module sorts the arcing characteristic signal values ​​of each arc fault detector by size, and determines the arcing fault location based on the arc fault detector corresponding to the largest arcing characteristic signal value obtained from the sorting.

[0017] Furthermore, if the distance between two adjacent arc detection modules in the photovoltaic array is less than the arc signal extension range of the arc fault in the photovoltaic array, and multiple arc fault detectors whose arc characteristic signal values ​​reach a preset threshold are not adjacent or whose spacing exceeds a preset distance value, then the main control module determines that the arc prediction result is a misjudgment result.

[0018] Furthermore, the arc detection module is positioned between two adjacent photovoltaic panels in the photovoltaic array, and the communication information between the arc fault detector and the main control module also includes the corresponding photovoltaic panel positioning information or photovoltaic panel position index information.

[0019] Furthermore, the arc fault detector includes a signal processing circuit unit and a power supply circuit unit that provides power to it, wherein the power supply circuit unit obtains power by connecting the positive and negative terminals of the corresponding photovoltaic panel.

[0020] Furthermore, the arc fault detector also includes a filter circuit unit, the input terminal of which is electrically connected to the electrical signal detector, and its output terminal is electrically connected to the signal processing circuit unit.

[0021] The filter circuit unit includes a first-stage filter circuit.

[0022] Furthermore, the arc fault detector is configured as a stand-alone module installed on the photovoltaic panel in the photovoltaic array, or it is configured to be integrated into the photovoltaic power optimizer or photovoltaic module shutdown device.

[0023] Furthermore, the electrical signal detector is a current transformer, and the communication circuit unit is a wired communication circuit or a wireless communication circuit;

[0024] The main control module is configured as a standalone module or integrated into the photovoltaic inverter.

[0025] On the other hand, the present invention also provides a photovoltaic system, including a photovoltaic inverter, distributed photovoltaic modules, and a distributed arc detection system as described above.

[0026] Furthermore, the present invention also provides a distributed arc detection method for detecting whether arcing occurs in the connection lines between photovoltaic panels in a photovoltaic array. The detection method includes the following steps:

[0027] Arc detection modules are pre-deployed in a distributed manner within the photovoltaic array;

[0028] If one of the arc detection modules detects an arcing signal, the following steps are performed:

[0029] Obtain the arc signal detection results from other arc detection modules. If none of the other arc detection modules detect the arc signal, then ignore the arc signal detected by one of the arc detection modules.

[0030] Furthermore, if at least one other arc detection module detects an arcing signal, it will respond to the photovoltaic array by taking action.

[0031] Furthermore, if at least one other arc detection module detects an arcing signal, and the spacing between two of the arc detection modules that detected the arcing signal is less than a preset distance value, then a response processing action is taken on the photovoltaic array; otherwise, the detected arcing signal is ignored.

[0032] Furthermore, after responding to the photovoltaic array, the process also includes:

[0033] Based on the partial or complete arc detection module that detects the arcing signal, the location of the corresponding photovoltaic panel is determined, and the wiring of the photovoltaic panel is inspected.

[0034] Furthermore, if at least one other arc detection module detects an arcing signal, the arcing characteristic signal values ​​detected by each arc detection module are sorted by size, and the arcing fault location is determined based on the arc detection module corresponding to the largest arcing characteristic signal value obtained from the sorting.

[0035] Furthermore, each arc detection module includes:

[0036] An electrical signal detector is configured to detect electrical signals at the location of the arc detection module;

[0037] An arc fault detector is configured to calculate arc characteristic signal values ​​based on the electrical signals detected by a corresponding electrical signal detector.

[0038] The communication circuit unit is configured to enable communication between the corresponding arc fault detector and the main control module of the detection system.

[0039] Furthermore, the communication circuit unit of the arc detection module communicates bidirectionally with the main control module;

[0040] In response to the arcing prediction result of one of the arc fault detectors, the main control module requests the arcing characteristic signal values ​​calculated by the other arc fault detectors. If the arcing characteristic signal values ​​of the other arc fault detectors are all lower than the preset threshold, the arcing prediction result is determined to be a misjudgment result.

[0041] Furthermore, if the arcing characteristic signal value of at least one of the other arc fault detectors reaches the preset threshold, the main control module triggers the photovoltaic module shutdown device of the photovoltaic array.

[0042] Furthermore, if the arcing characteristic signal value of at least one of the other arc fault detectors reaches the preset threshold, the main control module sorts the arcing characteristic signal values ​​of each arc fault detector by size, and determines the arcing fault location based on the arc fault detector corresponding to the largest arcing characteristic signal value obtained from the sorting.

[0043] Furthermore, if the distance between two adjacent arc detection modules in the photovoltaic array is less than the arc signal extension range of the arc fault in the photovoltaic array, and multiple arc fault detectors whose arc characteristic signal values ​​reach a preset threshold are not adjacent or whose spacing exceeds a preset distance value, then the main control module determines that the arc prediction result is a misjudgment result.

[0044] Furthermore, the arc detection module is positioned between two adjacent photovoltaic panels in the photovoltaic array, and the communication information between the arc fault detector and the main control module also includes the corresponding photovoltaic panel positioning information or photovoltaic panel position index information.

[0045] Furthermore, the arc fault detector includes a signal processing circuit unit and a power supply circuit unit that provides power to it, wherein the power supply circuit unit obtains power by connecting the positive and negative terminals of the corresponding photovoltaic panel.

[0046] Furthermore, the arc fault detector also includes a filter circuit unit, the input terminal of which is electrically connected to the electrical signal detector, and its output terminal is electrically connected to the signal processing circuit unit.

[0047] The filter circuit unit includes a first-stage filter circuit.

[0048] Furthermore, the arc fault detector is configured as a stand-alone module installed on the photovoltaic panel in the photovoltaic array, or it is configured to be integrated into the photovoltaic power optimizer or photovoltaic module shutdown device.

[0049] Furthermore, the electrical signal detector is a current transformer, and the communication circuit unit is a wired communication circuit or a wireless communication circuit;

[0050] The main control module is configured as a standalone module or integrated into the photovoltaic inverter.

[0051] The beneficial effects of the technical solution provided by this invention are as follows:

[0052] a. The distributed arc detection mode is less affected by machine noise, reducing false arc detections;

[0053] b. In the distributed arcing detection module, at least one module is close to the arcing fault point, resulting in less attenuation of the arcing characteristic signal and reducing missed arcing detections;

[0054] c. By identifying the identity or location of the detection module that detected arcing, the location of the arcing fault point can be located, which can be used as a reference for inspection personnel when troubleshooting the fault. Attached Figure Description

[0055] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0056] Figure 1This is a schematic diagram of the structure of a photovoltaic system with a distributed arc detection system provided in an embodiment of the present invention;

[0057] Figure 2 This is a schematic diagram showing the connection between a single arc detection module and a single photovoltaic panel provided in an embodiment of the present invention;

[0058] Figure 3 This is a schematic diagram of the structure of a simple filter circuit provided in an embodiment of the present invention;

[0059] Figure 4 This is a schematic diagram of the structure of a complex filter amplifier circuit in the prior art;

[0060] Figure 5 This is a schematic diagram of an arcing fault occurring in one string of a photovoltaic system provided in an embodiment of the present invention;

[0061] Figure 6 This is a schematic diagram of the basic process of distributed arc detection provided in the embodiments of the present invention;

[0062] Figure 7 This is a detailed flowchart illustrating the distributed arc detection process provided in an embodiment of the present invention. Detailed Implementation

[0063] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0064] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, apparatus, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0065] In one embodiment of the present invention, a distributed arc detection system is provided, comprising a main control module and multiple arc detection modules distributed in a photovoltaic array. A photovoltaic system having this distributed arc detection system is as follows: Figure 1 As shown, it includes a photovoltaic inverter, multiple photovoltaic panel strings, and multiple distributed arc detection modules. Each arc detection module includes:

[0066] In one embodiment, the electrical signal detector may be a current transformer (CT), such as... Figure 1 and Figure 2 As shown, the CT is configured to detect the current signal at the location of the arc detection module;

[0067] In one embodiment, the arc fault detector may be an arc fault detector (AFD), such as... Figure 1 As shown, the AFD is set between two photovoltaic panels and is configured to calculate the arcing characteristic signal value based on the electrical signal detected by the corresponding electrical signal detector.

[0068] A communication circuit unit, configured to enable communication between the corresponding arc fault detector and the main control module, can, in one embodiment of the invention, be part of the AFD (Automatic Field Control Device). The main control module is integrated within the photovoltaic inverter, and a communication network can be formed between the communication circuit units of each AFD and the communication circuit unit within the photovoltaic inverter. Clearly, it is equally feasible to have the communication circuit unit as an independent device located outside the AFD, or to have the main control module as an independent module located outside the photovoltaic inverter. Various devices that can communicate with it include inverters, photovoltaic module shutdown devices, and other distributed AFDs.

[0069] Specifically, such as Figure 2 As shown, the AFD includes an internal power supply circuit that can draw power from the positive and negative terminals of a nearby PV photovoltaic panel to power the internal electrical components of the AFD (such as the filter circuit unit, signal processing circuit unit, and communication circuit unit); the input terminal of the filter circuit unit is electrically connected to the CT, and its output terminal is electrically connected to the signal processing circuit unit.

[0070] Each AFD module acquires current signals through its own CT. Specifically, the arc detection CT is fitted onto the positive or negative line of the photovoltaic panel to sample the arc current signal. The arc signal is a high-frequency AC signal that is superimposed on the DC current. Since the output current of photovoltaic panels generally does not exceed 20A, the anti-saturation performance requirements of the CT core are relatively low, resulting in good economic efficiency. The signal sampled by the CT is filtered and amplified before being input to the signal processing circuit unit for analysis and calculation. If the arc characteristic signal calculated by the AFD exceeds a threshold, it is determined that a DC arc has been detected. The communication circuit unit in each module then sends the result to the inverter, the photovoltaic module's fast shutdown device, or other AFD modules. For example, the result is sent to the next-level judgment and circuit breaking device via the communication circuit to ultimately complete the arc extinguishing action. When one of the distributed AFDs detects an arcing fault, it can send information to the main control module (photovoltaic inverter) through the communication circuit unit. This invention differs from the prior art in that the arc detection device is integrated inside the photovoltaic inverter. In this embodiment, the arc detection modules are distributed outside the photovoltaic inverter, so they will not be affected by machine noise and thus will not cause false arcing alarms. If an arcing fault occurs at a connection point, at least one of the distributed arc detection modules will always be close to or relatively close to the arcing fault point, so there will be no missed arcing alarms caused by the weakening of the arc characteristic signal due to the long-distance line impedance.

[0071] In this embodiment, the distributed arc detection system has at least one arc detection module located closest to the arc occurrence position. This module can acquire the strongest arc signal. Therefore, the AFD's filtering circuit unit can be designed with a very simple structure. Figure 4 The commonly used filter amplifier circuit currently includes two stages of amplification, two stages of high-pass filtering, and two stages of low-pass filtering, resulting in a complex structure; while the embodiments of the present invention can employ... Figure 3 The simple filter circuit unit shown can consist of only one stage of low-pass filter circuit, or it can consist of one stage of differential amplifier circuit and one stage of low-pass filter circuit, with a simple structure.

[0072] The communication circuit unit can transmit the arcing fault signal and arcing-related parameter signals sent by the signal processing circuit unit to the photovoltaic inverter, photovoltaic module shutdown device, or other AFD modules, causing the inverter to disconnect from the grid or disconnect the DC side circuit, while simultaneously providing relevant information such as the arcing location. This communication circuit includes, but is not limited to, communication circuits using wired or wireless communication methods such as PLC, GPRS, and WIFI.

[0073] In one embodiment of the present invention, the distributed arc detection modules can also communicate with each other, either directly or indirectly through the communication circuit of the main control module and the AFD. In the latter case, the communication circuit unit of the arc detection module communicates bidirectionally with the main control module. Compared to the previous embodiment, this embodiment provides a detection system that further improves the accuracy of arc detection. The distance between two adjacent arc detection modules in the photovoltaic array is less than the arc signal extension range of the arc fault in the photovoltaic array. The operation process of its main control module is as follows:

[0074] In response to the arcing prediction result of one of the arc fault detectors (AFD), the main control module requests the arcing characteristic signal values ​​calculated by the other arc fault detectors. If the arcing characteristic signal values ​​of the other arc fault detectors are all lower than a preset threshold, or if multiple arc fault detectors with arcing characteristic signal values ​​reaching the preset threshold are not deployed adjacently or the deployment distance exceeds a preset distance value, then the arcing prediction result is determined to be a misjudgment result.

[0075] If the arc detection modules are distributed and communicate directly with each other, then when one arc fault detector (AFD) sends the arc prediction result to the other AFDs, the other AFDs will spontaneously send their calculated arc characteristic signal values ​​to the main control module.

[0076] In other words, when deploying CT and AFD, the spacing between adjacent arc detection modules is set according to the extension capability of the arc signal. For example, if there are five PV photovoltaic panels connected in series in the order of a, b, c, d, and e, and an arc occurs between a and b, the system detects whether an arc characteristic signal greater than a preset threshold can be detected between b and c, c and d, and d and e. If an arc can be detected between b and c, but not between c and d, then the arc detection modules need to be distributed as densely as possible throughout the photovoltaic array. Figure 1 As shown, the most dense arrangement involves placing an arc detection module between every two adjacent PV panels. However, if arcing can be detected between b and c, c and d, and d and e, it is not necessary to distribute them in the most dense manner throughout the PV array. Instead, they can be spaced out. For example, the first arc detection module (CT+AFD) can be placed between a and b, skipping the one between b and c, and the second arc detection module can be placed between c and d or between d and e. Figure 1 The diagram shows the most densely distributed AFD modules. In practical applications, an AFD module can be arranged every few photovoltaic panels as needed. The arc signal extension range needs to be determined based on the actual situation of the PV photovoltaic panels, and then the distributed arc detection modules should be deployed accordingly.

[0077] Under this premise, if an arc occurs at a point, at least two arc detection modules can detect it. Therefore, the main control module requests the arc characteristic signal values ​​calculated by the other arc fault detectors. If the result of the request is that no arc is detected, or the arc detection modules that detect the arc are not adjacent or close (secondary adjacent), then the arc prediction result is judged as a misjudgment result and ignored, that is, no intervention (shutdown) action is taken on the photovoltaic system.

[0078] Conversely, if the arcing characteristic signal value of at least one of the other arc fault detectors reaches the preset threshold, the main control module triggers the photovoltaic module shutdown device of the photovoltaic array. In another embodiment, it is further determined whether multiple AFDs that detect arcing are adjacent or close. "Close" means that if a first arcing detection module is set between photovoltaic panels a and b, and a second arcing detection module is set between c and d, then the first arcing detection module and the second arcing detection module are close, and are essentially adjacent, because there are no other arcing detection modules between them.

[0079] In one embodiment of the present invention, accurate location of arc fault points can be achieved in a distributed arc fault detection system. The specific scheme is as follows: If the arc fault characteristic signal value of at least one of the other arc fault detectors reaches the preset threshold, the main control module sorts the arc fault characteristic signal values ​​of each arc fault detector by size, and determines the arc fault location based on the arc fault detector corresponding to the largest arc fault characteristic signal value obtained from the sorting. As described above, the arc detection module is located between two adjacent photovoltaic panels in the photovoltaic array. The communication information from the arc fault detector to the main control module also includes the corresponding photovoltaic panel positioning information or photovoltaic panel position index information, such as sending the arc fault detector's own ID number, and further associating it with its corresponding PV photovoltaic panel through the arc fault detector ID number. Simultaneously, it can also determine whether these AFD modules sending arc fault characteristic signal values ​​exceeding the threshold are adjacent, and whether the voltage and current of the string in which the AFD sending arc fault characteristic signal values ​​exceeding the threshold are abnormally changing, thereby distinguishing whether the arcing is a series arcing, a ground arcing, or a parallel arcing. Figure 7As shown, if several AFDs with large arcing characteristic signal values ​​are adjacent or close together, and the voltage / current of the string containing these AFDs changes abnormally, it is determined to be a ground-to-ground arcing; if several AFDs with large arcing characteristic signal values ​​are adjacent or close together, and the voltage / current of the string containing these AFDs does not change abnormally, it is determined to be a series arcing; if several AFDs with large arcing characteristic signal values ​​are not adjacent or close together, and the voltage / current of the string containing these AFDs changes abnormally, it is determined to be a parallel arcing. Using these conditions to make a comprehensive judgment can reduce the possibility of false alarms from certain AFD modules due to interference in sporadic situations. Furthermore, it allows maintenance personnel to focus their inspection work on the area between the AFD with the strongest arcing characteristic signal value and several photovoltaic panels adjacent to it after an arcing fault occurs in the system. With a distributed AFD deployed on each photovoltaic panel, panel-level localization of the arcing fault can be achieved.

[0080] The signal processing circuit unit is used to calculate the signal after it has been processed by the filtering and amplification circuit. It uses time-domain, frequency-domain, or a combination of time-frequency domain calculation methods to determine whether an arcing fault exists and outputs an alarm signal and arcing-related parameter signals. Depending on the calculation method used, this signal processing circuit unit can be implemented solely by hardware circuitry or through a microcontroller software algorithm. Figure 5 This diagram illustrates an arcing fault. For example, a string of photovoltaic inverters consists of seven photovoltaic panels, PV1-PV7, each equipped with a distributed arc detection device (AFD1-AFD7). If an arc occurs between photovoltaic panels PV2 and PV3, the AFD3, the closest distributed arc detection module to the arcing location, will detect the strongest arcing characteristic signal. The arcing characteristic signals detected by AFD2 and AFD4 will be attenuated compared to those detected by AFD3 due to the distributed capacitance between the cables and the photovoltaic panels to ground. However, they will still be stronger than the arcing characteristic values ​​detected by AFDs further away. Therefore, if an AFD detects an arcing characteristic value exceeding a threshold, before the inverter finally determines that an arcing fault has caused grid disconnection and shutdown, it is possible to further improve the accuracy of arcing detection by checking whether the IDs of several AFDs sending arcing characteristic signal values ​​exceeding the threshold are adjacent or similar. The ID number of the AFD with the largest arcing characteristic signal value is then sent to facilitate fault location.

[0081] Utilizing this feature, photovoltaic inverters can mark and analyze distributed arc fault detection (AFD) devices that trigger arcing alarms when reaching the threshold, thus identifying the AFD closest to the arcing location. The threshold is derived from extensive arcing tests conducted in actual power plants, summarizing various arcing characteristic values, including but not limited to time-domain peak value, maximum value, and frequency-domain amplitude values ​​affected by the arc. Specific arcing detection methods are as follows... Figure 6As shown: Each AFD continuously collects and processes current signals through a CT to obtain various arcing characteristic values. If these characteristic values ​​reach a threshold, an alarm signal and ID value are immediately issued. Simultaneously, the arcing characteristic value triggered at the threshold is also sent. This arcing characteristic value can be a time-domain peak value, maximum value, or frequency-domain amplitude value, all influenced by the electric arc. The inverter finds the ID value of the AFD device corresponding to the maximum value among the obtained arcing characteristic values ​​and determines whether it is adjacent or close to the ID of the AFD with a larger arcing characteristic value. This value is then displayed to the user or inspection personnel, providing troubleshooting suggestions.

[0082] In this embodiment, the arc fault detector (AFD) has multiple configuration forms. For example, it can be configured as an independent module installed on the photovoltaic panels in the photovoltaic array, or it can be integrated into the photovoltaic power optimizer or photovoltaic module shutdown device. If it is attached to the photovoltaic power optimizer or photovoltaic module shutdown device, it can share its power supply circuit, microcontroller computing power, or shutdown circuit, further reducing hardware costs. The microcontroller computing power used in its module can be very small, and the impact on the original function is negligible. Because distributed arc detection can detect the strongest arc signal by the AFD module closest to the arc point, it experiences less interference and signal attenuation. Therefore, the arc detection algorithm does not require the complex microcontrollers of traditional methods that require high computing power; a simple algorithm can achieve good results. Furthermore, by utilizing the shutdown circuit of the photovoltaic power optimizer or photovoltaic module shutdown device through the communication circuit, the arc can be quickly extinguished.

[0083] In one embodiment of the present invention, a distributed arc detection method is provided for detecting whether arcing occurs in the connection lines between photovoltaic panels in a photovoltaic array. The detection method includes the following steps:

[0084] Arc detection modules are pre-deployed in a distributed manner within the photovoltaic array;

[0085] If one of the arc detection modules detects an arcing signal, the following steps are performed:

[0086] Obtain the detection results of the arc signal from other arc detection modules. If none of the other arc detection modules detect the arc signal, then ignore the arc signal detected by one of the arc detection modules.

[0087] If at least one other arc detection module detects an arcing signal, a response action is taken on the photovoltaic array; or,

[0088] If at least one other arc detection module detects an arcing signal, and the spacing between two of the arc detection modules that detected the arcing signal is less than a preset distance value, then the photovoltaic array will be processed accordingly; otherwise, the detected arcing signal will be ignored.

[0089] This arc detection method embodiment and the above-described arc detection system embodiment belong to the same inventive concept. All contents of the above-described system embodiment are incorporated into this method embodiment by reference, and will not be repeated here.

[0090] Preferably, after responding to the photovoltaic array, the process further includes:

[0091] Based on the partial or complete arc detection modules that detected the arcing signal, the locations of multiple corresponding photovoltaic panels are determined, and the wiring of the photovoltaic panels is inspected. This narrows the fault investigation scope to the photovoltaic panels corresponding to the arc detection modules that detected the arcing signal, improving fault repair efficiency.

[0092] In this embodiment of the invention, the level of arc fault location is further improved by the following implementation method: When at least one other arc detection module detects an arc signal, the arc characteristic signal values ​​detected by each arc detection module are sorted by size, and the arc fault location is determined according to the arc detection module corresponding to the largest arc characteristic signal value obtained by sorting. For example, the arc fault detector can be associated with its corresponding PV photovoltaic panel by sending its own ID number, or the location information of the PV photovoltaic panel can be sent directly.

[0093] Distributed AFD (Automatic Field Deposition) devices can be positioned closer to potential arcing locations, reducing the impact of cable impedance and photovoltaic panel-to-ground capacitance on arcing signal attenuation, resulting in higher detection accuracy and better performance in high-power photovoltaic systems. Furthermore, they are significantly less susceptible to interference from inverter noise, reducing the likelihood of false arcing detections. Additionally, the ID of the AFD device detecting arcing characteristics can pinpoint the location of the arcing fault, significantly reducing maintenance and troubleshooting work.

[0094] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0095] The above description is only a specific embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A distributed arc detection method, characterized in that, The detection method for detecting whether arcing occurs in the connection lines between photovoltaic panels in a photovoltaic array includes the following steps: Multiple arc detection modules are pre-distributed in the photovoltaic array; the spacing between two adjacent arc detection modules in the photovoltaic array is less than the arc signal extension range of the arc fault in the photovoltaic array. If one of the arc detection modules detects an arcing signal, the following steps are performed: Obtain the arc signal detection results from other arc detection modules. If none of the other arc detection modules detect the arc signal, then ignore the arc signal detected by one of the arc detection modules.

2. The distributed arc detection method according to claim 1, characterized in that, If at least one other arc detection module detects an arcing signal, it will respond to the photovoltaic array.

3. The distributed arc detection method according to claim 1, characterized in that, If at least one other arc detection module detects an arcing signal, and the spacing between two of the arc detection modules that detected the arcing signal is less than a preset distance value, then the photovoltaic array will be processed accordingly; otherwise, the detected arcing signal will be ignored.

4. The distributed arc detection method according to claim 1, characterized in that, After responding to the photovoltaic array, the process also includes: Based on the partial or complete arc detection module that detects the arcing signal, the location of the corresponding photovoltaic panel is determined, and the wiring of the photovoltaic panel is inspected.

5. The distributed arc detection method according to claim 1, characterized in that, If at least one other arc detection module detects an arcing signal, the arcing characteristic signal values ​​detected by each arc detection module are sorted by size, and the arcing fault location is determined based on the arc detection module corresponding to the largest arcing characteristic signal value obtained from the sorting.

6. The distributed arc detection method according to claim 1, characterized in that, Each arc detection module includes: An electrical signal detector is configured to detect electrical signals at the location of the arc detection module; An arc fault detector is configured to calculate arc characteristic signal values ​​based on the electrical signals detected by a corresponding electrical signal detector. The communication circuit unit is configured to enable communication between the corresponding arc fault detector and the main control module of the detection system.

7. The distributed arc detection method according to claim 6, characterized in that, The communication circuit unit of the arc detection module communicates bidirectionally with the main control module; In response to the arcing prediction result of one of the arc fault detectors, the main control module requests the arcing characteristic signal values ​​calculated by the other arc fault detectors. If the arcing characteristic signal values ​​of the other arc fault detectors are all lower than the preset threshold, the arcing prediction result is determined to be a misjudgment result.

8. The distributed arc detection method according to claim 7, characterized in that, If the arcing characteristic signal value of at least one of the other arc fault detectors reaches the preset threshold, the main control module triggers the photovoltaic module shutdown device of the photovoltaic array.

9. The distributed arc detection method according to claim 7, characterized in that, If the arcing characteristic signal value of at least one of the other arc fault detectors reaches the preset threshold, the main control module sorts the arcing characteristic signal values ​​of each arc fault detector by size, and determines the arc fault location based on the arc fault detector corresponding to the largest arcing characteristic signal value obtained from the sorting.

10. The distributed arc detection method according to claim 7, characterized in that, If multiple arc fault detectors whose arcing characteristic signal values ​​reach a preset threshold are not deployed adjacently or whose deployment spacing exceeds a preset distance value, the main control module determines that the arcing prediction result is a misjudgment result.

11. The distributed arc detection method according to claim 6, characterized in that, The arc detection module is positioned between two adjacent photovoltaic panels in the photovoltaic array. The communication information between the arc fault detector and the main control module also includes the corresponding photovoltaic panel positioning information or photovoltaic panel position index information.

12. The distributed arc detection method according to claim 6, characterized in that, The arc fault detector includes a signal processing circuit unit and a power supply circuit unit that provides power to it, wherein the power supply circuit unit obtains power by connecting the positive and negative terminals of the corresponding photovoltaic panel.

13. The distributed arc detection method according to claim 12, characterized in that, The arc fault detector further includes a filter circuit unit, the input terminal of which is electrically connected to the electrical signal detector, and its output terminal is electrically connected to the signal processing circuit unit. The filter circuit unit includes a first-stage filter circuit.

14. The distributed arc detection method according to claim 6, characterized in that, The arc fault detector is configured as a stand-alone module installed on the photovoltaic panel in the photovoltaic array, or it is configured to be integrated into the photovoltaic power optimizer or photovoltaic module shutdown device.

15. The distributed arc detection method according to claim 6, characterized in that, The electrical signal detector is a current transformer, and the communication circuit unit is a wired communication circuit or a wireless communication circuit; the main control module is configured as an independent module or integrated into the photovoltaic inverter.

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