String-level dc arc fault detection apparatus for photovoltaic power plants and photovoltaic systems

Abstract

This utility model discloses a detection device and photovoltaic system for string-level DC arcing faults in photovoltaic power plants. The detection device includes a signal acquisition module, a processing module, and a switching module. The signal acquisition module is connected to the power supply circuit of the photovoltaic string and is used to acquire electrical parameters in the power supply circuit, which are analog detection signals. The processing module is connected to the signal acquisition module and is used to convert the analog detection signals into digital detection signals, extract features from the digital detection signals, and identify whether the digital detection signals are arcing signals or normal disturbance signals. The switching module is connected in series in the power supply circuit of the photovoltaic string. The processing module is used to control the switching module to open when the digital detection signal is an arcing signal; the processing module is also used to control the switching module to close after the arcing fault is repaired. This utility model helps to reduce the cost of installing arcing fault detection devices in old photovoltaic power plants.

Description

Technical Field

[0001] This utility model relates to the field of photovoltaic power plant safety protection technology, and in particular to a detection device and photovoltaic system for string-level DC arcing faults in photovoltaic power plants. Background Technology

[0002] my country's photovoltaic (PV) industry has developed rapidly on a large scale, with the cumulative installed capacity exceeding 700 GW nationwide. However, many aging PV power plants, some of which have been in operation for over five years, suffer from problems such as aging cables and loose connections. The DC side of PV systems operates at high voltage; insulation damage and poor contact can induce DC arcing, which can easily cause fires and threaten the safety of PV power plants.

[0003] Older photovoltaic (PV) power plants generally lack arc fault detection devices, while the arc fault detection devices used in newly built PV power plants are mostly built into the inverters. These devices can only be deployed during the early planning stages of PV power plants and the inverter manufacturing stage, making them suitable for brand-new PV power plants but not directly applicable to existing older PV power plants. Replacing the entire existing inverter in an older PV power plant to install an arc fault detection device would result in high retrofit costs. Utility Model Content

[0004] This utility model provides a detection device and photovoltaic system for string-level DC arcing faults in photovoltaic power plants, which solves the technical problem that adding arcing fault detection devices to old photovoltaic power plants requires replacing the inverter, resulting in high costs.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: In a first aspect, embodiments of this utility model provide a detection device for string-level DC arcing faults in photovoltaic power plants, comprising: The signal acquisition module is connected to the power supply circuit of the photovoltaic string and is used to acquire the electrical parameters in the power supply circuit, wherein the electrical parameters are analog detection signals; The processing module, connected to the signal acquisition module, is used to convert the analog detection signal into a digital detection signal, extract features from the digital detection signal, and identify the digital detection signal as a fault signal or a normal disturbance signal generated by arcing. A switching module is connected in series in the power supply circuit of the photovoltaic string; the processing module is used to control the switching module to open in the event that the digital detection signal is a fault signal generated by arcing, so as to cut off the power supply circuit of the photovoltaic string; the processing module is also used to control the switching module to close after the arcing fault is repaired, so as to turn on the power supply circuit of the photovoltaic string.

[0006] Optionally, the detection device for string-level DC arcing faults in photovoltaic power plants further includes: A frequency selection module is connected between the signal acquisition module and the processing module. The frequency selection module only allows the analog detection signal of the preset frequency band to enter the processing module.

[0007] Optionally, the detection device for string-level DC arcing faults in photovoltaic power plants further includes: A signal conditioning module, connected between the frequency selection module and the processing module, is used to amplify and filter the analog detection signal.

[0008] Optionally, the signal acquisition module is an arc-coupled coil.

[0009] Optionally, the switching module includes a driving circuit and a switching transistor; The driving circuit is used to drive the switching transistor to disconnect according to the first control signal issued by the processing module when the digital detection signal is a fault signal generated by arcing; the driving circuit is also used to drive the switching transistor to close according to the second control signal issued by the processing module after the arcing fault is repaired.

[0010] Optionally, the switching transistor is a silicon carbide metal-oxide-semiconductor field-effect transistor.

[0011] Optionally, the processing module includes an analog-to-digital conversion unit, which is used to convert the analog detection signal into the digital detection signal.

[0012] Optionally, the detection device for string-level DC arcing faults in photovoltaic power plants further includes: A communication module, connected to the processing module, is used to upload arcing fault information to the terminal device after the processing module identifies the digital detection signal as an arcing signal.

[0013] Optionally, the detection device for string-level DC arcing faults in photovoltaic power plants further includes: A power supply module, connected to the processing module, is used to supply power to the processing module.

[0014] Secondly, this utility model also provides a photovoltaic system, including: a photovoltaic string, an inverter, and a string-level DC arcing fault detection device for a photovoltaic power station as described in any embodiment of this utility model.

[0015] The string-level DC arcing fault detection device for photovoltaic power plants provided in this embodiment is adaptable to photovoltaic power plants of different years of operation and different types. The signal acquisition module and switch module are externally connected to the power supply circuit of the photovoltaic string, eliminating the need to replace the original inverter of the old photovoltaic power plant. This solves the problems of high modification cost, difficult construction and modification, and poor equipment compatibility when retrofitting by replacing the inverter with one that has a built-in arcing fault detection device.

[0016] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this utility model, nor is it intended to limit the scope of this utility model. Other features of this utility model will become readily apparent from the following description. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of this utility model and these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of a detection device for string-level DC arcing faults in a photovoltaic power station, provided by an embodiment of this utility model. Figure 2 This is a schematic diagram of another detection device for string-level DC arcing faults in photovoltaic power plants provided in this embodiment of the present invention; Figure 3 This is a schematic diagram of another detection device for string-level DC arcing faults in photovoltaic power plants provided in this embodiment of the present invention; Figure 4 This is a schematic diagram of another detection device for string-level DC arcing faults in photovoltaic power plants provided in this embodiment of the present invention; Figure 5 This is a schematic diagram of another detection device for string-level DC arcing faults in photovoltaic power plants provided by an embodiment of this utility model. Detailed Implementation

[0019] 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. 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 protection scope of the present invention.

[0020] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model 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 utility model 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 non-exclusive inclusion; for example, a process, method, system, product, or apparatus 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 apparatus.

[0021] This utility model provides a detection device for string-level DC arcing faults in photovoltaic power plants. Figure 1 This is a schematic diagram of a detection device for string-level DC arcing faults in photovoltaic power plants, provided in an embodiment of this utility model. (See also...) Figure 1 A detection device for string-level DC arcing faults in photovoltaic power plants includes a signal acquisition module 110, a processing module 120, and a switching module 130. The signal acquisition module 110 is connected to the power supply circuit of the photovoltaic string 200 and is used to acquire electrical parameters in the power supply circuit, which are analog detection signals. The processing module 120 is connected to the signal acquisition module 110 and is used to convert the analog detection signals into digital detection signals, extract features from the digital detection signals, and identify whether the digital detection signals are fault signals caused by arcing or normal disturbance signals. The switching module 130 is connected in series in the power supply circuit of the photovoltaic string 200. The processing module 120 is used to control the switching module 130 to open when the digital detection signal is a fault signal caused by arcing, thereby cutting off the power supply circuit of the photovoltaic string 200. The processing module 120 is also used to control the switching module 130 to close after the arcing fault is repaired, thereby connecting the power supply circuit of the photovoltaic string 200.

[0022] The photovoltaic power station includes a photovoltaic string 200 and an inverter 300. The photovoltaic string 200 consists of multiple photovoltaic modules 210 connected in series. The photovoltaic string 200 receives sunlight to generate DC power, which is then converted into AC power by the inverter 300 and output to the load for use or connected to the mains power grid. In older photovoltaic power stations, abnormal operating conditions such as aging and damaged cable insulation or loose and faulty connections may occur between the photovoltaic modules 210. Therefore, the power supply circuit of the photovoltaic string 200 is prone to DC arcing, which can lead to fire hazards.

[0023] The power supply circuit of the photovoltaic string 200 refers to the electrical circuit of the photovoltaic string 200 formed by multiple photovoltaic modules 210 connected in series. Specifically, the power supply circuit of the photovoltaic string 200 includes a series connection between two adjacent photovoltaic modules 210, which connects the positive and negative terminals of the two photovoltaic modules 210 respectively. The power supply circuit of the photovoltaic string 200 also includes the connection lines between the positive terminal of the photovoltaic string 200 and the inverter 300, and the connection lines between the negative terminal of the photovoltaic string 200 and the inverter 300.

[0024] For example, the process of upgrading an old photovoltaic power station using the string-level DC arcing fault detection device for photovoltaic power stations provided in this embodiment of the invention is as follows: The signal acquisition module 110 is installed in the power supply circuit of the photovoltaic string 200, and can be deployed without cutting the cable. The switch module 130 is connected in series between two adjacent photovoltaic modules 210. During installation, the cable between the adjacent photovoltaic modules 210 needs to be disconnected, and the switch module 130 is connected in series between the positive terminal of one photovoltaic module 210 and the negative terminal of the other photovoltaic module 210.

[0025] The signal acquisition module 110 is connected to the power supply circuit of the photovoltaic string 200 and can acquire analog detection signals of electrical parameters such as voltage or current in the power supply circuit of the photovoltaic string 200 in real time. The analog detection signal can comprehensively reflect the real-time operating status of the photovoltaic string 200 and provide complete and effective raw signal support for the back-end processing module 120 to identify arcing faults.

[0026] The processing module 120 is the core of the entire detection device for computation and control. For example, the processing module 120 can employ a low-power microprocessor (MCU). The specific logic for the processing module 120 to extract features from the digital detection signal and identify whether the digital detection signal is a fault signal generated by arcing or a normal disturbance signal can refer to existing technologies or be implemented using the embodiments of this utility model. In this embodiment, for example, the processing module 120 receives the analog detection signal output by the signal acquisition module 110, converts the continuous analog detection signal into a digital detection signal that can be recognized and processed by the processor in the processing module 120, and then extracts and analyzes the time-domain and frequency-domain features of the digital detection signal. A convolutional neural network is then used to intelligently classify and identify the digital detection signal after feature extraction, accurately distinguishing whether the current digital detection signal is a fault signal generated by arcing or a normal disturbance signal caused by light fluctuations or the switching on / off of the inverter 300, effectively avoiding misjudgment and missed judgment. Furthermore, the extraction and analysis of time-domain and frequency-domain features of the digital detection signal can distinguish the unique signal characteristics of series arcs and parallel arcs. For example, a series arc will cause significant current fluctuations in the power supply circuit of the photovoltaic string 200, which manifests in the time domain as a continuous decay of current amplitude and sparse pulse distribution. A parallel arc will cause only slight current changes in the power supply circuit of the photovoltaic string 200, but the discharge process of a parallel arc will generate dense high-frequency pulses in a specific frequency band. This embodiment can capture the differentiated waveform information of the two types of arcs by extracting and analyzing the time-domain and frequency-domain features of the digital detection signal. Therefore, this embodiment can not only identify series arcs, but also parallel arcs that are difficult to detect using a single current threshold judgment scheme in related technologies.

[0027] The switch module 130 is connected in series in the power supply circuit of the photovoltaic string 200 and is a power device that performs power supply circuit on / off control. The switch module 130 receives control signals from the processing module 120 and performs corresponding cut-off or on / off operations on the power supply circuit. Specifically, when the processing module 120 detects a normal disturbance signal in the digital detection signal, the processing module 120 maintains the original control state and continues to control the switch module 130 to remain closed, allowing the photovoltaic string 200 to generate electricity normally. When the processing module 120 detects a fault signal caused by arcing in the digital detection signal, the processing module 120 outputs a shutdown control signal, controlling the switch module 130 to open, physically cutting off the power supply circuit of the entire photovoltaic string 200. This embodiment of the invention, by timely cutting off the power supply circuit of the photovoltaic string 200, can quickly cut off the source of arcing energy, achieve instantaneous arc extinguishing, prevent the continuous high-temperature combustion of DC arcing from igniting cables and photovoltaic modules 210, and effectively avoid the occurrence of photovoltaic power station fire accidents. After the maintenance personnel have investigated and completely repaired the arcing fault, the processing module 120 can output a conduction control signal to control the switch module 130 to close, thereby reconnecting the power supply circuit of the photovoltaic string 200 and restoring the photovoltaic string 200 to normal power generation and supply status.

[0028] The string-level DC arcing fault detection device for photovoltaic power plants provided in this embodiment is adaptable to photovoltaic power plants of different years of operation and different types. The signal acquisition module 110 and the switch module 130 are externally connected to the power supply circuit of the photovoltaic string 200, eliminating the need to replace the original inverter 300 of the old photovoltaic power plant. This solves the problems of high modification cost, difficult construction and modification, and poor equipment compatibility when retrofitting by replacing the inverter 300 with a built-in arcing fault detection device.

[0029] Figure 2 This is a schematic diagram of another detection device for string-level DC arcing faults in photovoltaic power plants provided in this embodiment of the invention. (See also...) Figure 2 Based on the above embodiments, optionally, the detection device for string-level DC arcing faults in photovoltaic power plants further includes a frequency selection module 140. The frequency selection module 140 is connected between the signal acquisition module 110 and the processing module 120, and the frequency selection module 140 only allows analog detection signals of a preset frequency band to enter the processing module 120.

[0030] The preset frequency band analog detection signal refers to the high-frequency characteristic signal generated by discharge radiation when a series or parallel arcing fault occurs in the power supply circuit of the photovoltaic string 200. The original analog detection signal output by the signal acquisition module 110 is mixed with a large amount of environmental and equipment operation interference noise. The frequency selection module 140 only conducts the analog detection signal corresponding to the preset frequency band of the arcing fault, filtering out interference noise in other frequency bands. The fault signal generated by the parallel arc has a weak amplitude and is easily masked by noise. After being filtered by the frequency selection module 140, the effective characteristic signal of the parallel arc is highlighted, which can ensure that the processing module 120 can simultaneously identify series and parallel arcs, effectively suppressing the misjudgment of arcing faults under complex operating conditions.

[0031] Based on the above embodiments, the frequency selection module 140 may optionally be a passive RC bandpass filter composed of resistors and capacitors, a passive LC bandpass filter composed of inductors and capacitors, or an active bandpass filter constructed from operational amplifiers. This invention does not limit the type of frequency selection module; in practical applications, a suitable frequency selection module can be selected according to requirements.

[0032] Figure 3 This is a schematic diagram of another detection device for string-level DC arcing faults in photovoltaic power plants provided in this embodiment of the invention. (See also...) Figure 3 Based on the above embodiments, optionally, the detection device for string-level DC arcing faults in photovoltaic power plants further includes a signal conditioning module 150. The signal conditioning module 150 is connected between the frequency selection module 140 and the processing module 120, and is used to amplify and filter the analog detection signal.

[0033] The original analog detection signal acquired by the signal acquisition module 110 has a small amplitude. Even after being filtered by the frequency selection module 140, the effective signal still contains a small amount of residual noise, which cannot directly meet the sampling requirements of the back-end processing module 120. The signal conditioning module 150 amplifies the analog detection signal in the preset frequency band output by the frequency selection module 140 to prevent the fault signal generated by arcing from having too low an amplitude to be identified. The signal conditioning module 150 also performs filtering to further filter out electromagnetic noise interference in the same frequency band as the fault signal generated by arcing, optimize waveform quality, and improve the signal-to-noise ratio. The analog detection signal waveform after conditioning by the signal conditioning module 150 is more regular and the arcing fault characteristics are clearer, making it easier for the processing module 120 to clearly extract the time-domain and frequency-domain characteristics of the fault signal generated by arcing, effectively reducing the risk of missed or false detection of arcing faults.

[0034] Based on the above embodiments, optionally, the signal conditioning module 150 is a signal conditioning circuit composed of an operational amplifier and resistors and capacitors. Alternatively, the signal conditioning module 150 is a conditioning circuit composed of a dedicated integrated signal conditioning chip and external resistors and capacitors. This utility model does not limit the type of signal conditioning module 150; in practical applications, a suitable signal conditioning module 150 can be selected according to requirements.

[0035] Based on the above embodiments, the signal acquisition module 110 may optionally be an arc coupling coil.

[0036] The arc coupling coil is a non-contact inductive acquisition device, installed on the power supply trunk line of the photovoltaic string 200. Installation and adaptation can be completed without cutting the existing DC cable, meeting the retrofit requirements of older photovoltaic power plants. This arc coupling coil possesses wide-band induction characteristics, capable of sensing not only the current fluctuation signal in the power supply circuit of the photovoltaic string 200 caused by series arcs, but also capturing the high-frequency electromagnetic signals radiated outwards by parallel arc discharges. For example, the arc coupling coil employs an openable / closable magnetic core structure.

[0037] Figure 4 This is a schematic diagram of another detection device for string-level DC arcing faults in photovoltaic power plants provided in this embodiment of the invention. (See also...) Figure 4 Based on the above embodiments, optionally, the switching module 130 includes a driving circuit 131 and a switching transistor 132. The driving circuit 131 is used to drive the switching transistor 132 to open according to a first control signal issued by the processing module 120 when the digital detection signal is a fault signal generated by arcing. The driving circuit 131 is also used to drive the switching transistor 132 to close according to a second control signal issued by the processing module 120 after the arcing fault is repaired.

[0038] The control signal output by the processing module 120 has limited driving capability and cannot directly drive the switch 132 to open or close. The drive circuit 131 is a signal power amplification and level conversion circuit that can receive the control signal sent by the processing module 120 and perform power amplification and level conversion. When the processing module 120 identifies the digital detection signal as a fault signal caused by arcing, the processing module 120 outputs a first control signal, i.e., a shutdown control signal. After receiving the first control signal, the drive circuit 131 outputs a drive level, causing the switch 132 to open quickly, cutting off the power supply circuit of the photovoltaic string 200 and achieving arc extinguishing and fire prevention. After the maintenance personnel have investigated and eliminated the potential arcing fault, the processing module 120 outputs a second control signal, i.e., a conduction control signal. The drive circuit 131 drives the switch 132 to close according to the second control signal, conducting the power supply circuit of the photovoltaic string 200.

[0039] For example, the drive circuit 131 is constructed from a drive chip and its peripheral circuitry. This drive chip has a fault-locking function and a remote reset function. When the processing module 120 detects a fault signal caused by arcing in the digital detection signal and outputs a first control signal to the drive circuit 131 to turn off the switch 132, the drive chip enters a fault-locking state, causing the switch 132 to remain open and unable to close automatically. After maintenance personnel have investigated and eliminated the potential arcing fault on-site, they can issue a remote reset command to the drive chip to release its fault-locking state. After the fault-locking state of the drive chip is released, the processing module 120 can output a second control signal to the drive circuit 131 to close the switch 132, thereby turning on the power supply circuit of the photovoltaic string 200.

[0040] Based on the above embodiments, the switching transistor 132 may optionally be a silicon carbide metal-oxide-semiconductor field-effect transistor (SiC MOSFET).

[0041] Among them, SiC MOSFETs have advantages such as high voltage withstand capability, fast switching speed, low conduction loss, and high temperature resistance. The turn-off response time of a SiC MOSFET is less than 2ms. This embodiment of the invention uses a SiC MOSFET as the switching transistor 132. On the one hand, it can quickly turn off when an arcing fault is detected, rapidly cutting off the power supply circuit of the photovoltaic string 200 and achieving arc extinguishing. On the other hand, it can reduce power loss during normal power generation of the photovoltaic string 200, making it suitable for the high-temperature outdoor operating environment of photovoltaic power stations.

[0042] In one embodiment, the switch module 130 may optionally include a manual reset switch connected to the drive circuit 131.

[0043] For example, the manual reset switch is a field-operable physical button connected to the driver chip in the drive circuit 131. After maintenance personnel have investigated and eliminated potential arcing faults on-site, they can press the manual reset switch to release the fault self-locking state of the driver chip in the drive circuit 131, causing the switch module 130 to close again. This structure of the switch module 130 effectively prevents the power supply circuit of the photovoltaic string 200 from automatically turning on when the arcing fault has not been completely eliminated, avoiding the re-induction of arcing, eliminating the risk of secondary fire, and improving the operational safety level of the photovoltaic power station.

[0044] Based on the above embodiments, the processing module 120 may optionally include an analog-to-digital conversion unit, which is used to convert analog detection signals into digital detection signals.

[0045] The analog detection signal output by the signal acquisition module 110 is a continuously changing electrical signal. The analog-to-digital conversion unit may include an analog-to-digital conversion chip and its peripheral circuitry. The analog-to-digital conversion unit can convert the signal format, periodically sampling, quantizing, and encoding the analog detection signal after passing through the frequency selection module 140 and the signal conditioning module 150, converting the continuous analog detection signal into a digital detection signal that can be read by the processing module 120. The converted digital detection signal can then be further processed for time-domain and frequency-domain feature extraction and fed into a convolutional neural network to complete arc fault identification.

[0046] Figure 5 This is a schematic diagram of another detection device for string-level DC arcing faults in photovoltaic power plants provided in this embodiment of the invention. (See also...) Figure 5 Based on the above embodiments, optionally, the detection device for string-level DC arcing faults in photovoltaic power plants further includes a communication module 160. The communication module 160 is connected to the processing module 120 and is used to upload arcing fault information to the terminal device after the processing module 120 identifies the digital detection signal as an arcing signal.

[0047] After the processing module 120 determines the arcing fault, it can send arcing fault information, such as the arcing fault type, the time of arcing occurrence, and arcing characteristic parameters, to the communication module 160. The communication module 160 establishes a data transmission channel with the remote terminal device, remotely uploads the arcing fault information to the terminal device, and automatically generates a maintenance work order on the terminal device. Maintenance personnel can obtain fault alarms in a timely manner through the terminal device, facilitating the immediate implementation of photovoltaic power station shutdown protection and on-site maintenance. For example, the communication module 160 is a programmable logic controller (PLC).

[0048] See also Figure 5 Based on the above embodiments, optionally, the detection device for string-level DC arcing faults in photovoltaic power plants further includes a power supply module 170. The power supply module 170 is connected to the processing module 120 and is used to supply power to the processing module 120.

[0049] The power supply module 170 is an independent external power source, and the processing module 120 does not draw power from the photovoltaic string 200's circuit. Even if the power supply circuit of the photovoltaic string 200 experiences an arcing fault and disconnects, the processing module 120 will not lose power and can continue to operate.

[0050] Optionally, the power supply module 170 can also supply power to the signal acquisition module 110, the switching module 130, the frequency selection module 140, the signal conditioning module 150, and the communication module 160. In practical applications, the power supply module 170 can be flexibly selected to supply power to each module based on its hardware type. If a module requires external power, the power supply module 170 will supply it; if a module has self-powering capabilities or does not require power, the power supply module 170 will not be needed.

[0051] In summary, the detection device for string-level DC arcing faults in photovoltaic power plants provided in this embodiment of the invention acquires the original analog detection signals in the power supply circuit of the photovoltaic string 200 in real time through the signal acquisition module 110, which can capture the characteristic signals of series arcs and parallel arcs. The frequency selection module 140 filters out environmental interference and noise, selecting the effective signals corresponding to the fault signals generated by the arcing. The signal conditioning module 150 amplifies and filters the weak fault signals generated by the arcing, optimizing waveform quality and improving the signal-to-noise ratio. The optimized analog detection signal is sent to the processing module 120 for analog-to-digital conversion to obtain a resolvable digital detection signal. The processing module 120 extracts and analyzes the time-domain and frequency-domain features of the digital detection signal, and uses a convolutional neural network to intelligently classify and identify the digital detection signal after feature extraction, accurately distinguishing whether the digital detection signal is a fault signal generated by arcing or a normal disturbance signal. When the digital detection signal indicates a fault signal caused by arcing, the processing module 120 controls the switch module 130 to disconnect, quickly cutting off the power supply circuit of the photovoltaic string 200 to achieve arc extinction protection. Simultaneously, the fault alarm information is uploaded via the communication module 160, supporting remote operation and maintenance monitoring. After the arcing fault is cleared, the switch module 130 can be closed manually or remotely to restore normal power generation operation of the photovoltaic string 200. This embodiment of the invention achieves the following beneficial effects: 1. It solves the technical problems of high difficulty in detecting arcing faults in traditional old photovoltaic power plants, high false alarm rate under complex operating conditions, difficulty in equipment modification, and poor compatibility of arcing detection devices. It can be adapted to photovoltaic power plants of different ages and types.

[0052] 2. A low-cost and easy-to-deploy DC arcing fault detection device is provided, which can complete the on-site transformation without replacing the original inverter 300 and photovoltaic module 210, greatly reducing the construction and operation and maintenance costs of photovoltaic power station transformation.

[0053] 3. Relying on time-domain and frequency-domain feature extraction and convolutional neural network intelligent recognition algorithms, it can achieve full coverage recognition of series arcs and parallel arcs, and complete millisecond-level fault disconnection in conjunction with switch module 130; at the same time, combined with communication module 160, it can realize remote fault alarm and operation and maintenance linkage, effectively avoid the risk of DC arcing and fire, and improve the operation safety and power generation revenue stability of photovoltaic power plants.

[0054] This utility model embodiment also provides a photovoltaic system. The photovoltaic power station includes a photovoltaic string 200, an inverter 300, and a string-level DC arcing fault detection device for a photovoltaic power station as provided in any embodiment of this utility model, and has corresponding beneficial effects.

[0055] It should be understood that the various forms of the process shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this utility model can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this utility model can be achieved, and this is not limited herein.

[0056] The specific embodiments described above do not constitute a limitation on the scope of protection of this utility model. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A detection device for string-level DC arcing faults in photovoltaic power plants, characterized in that, include: The signal acquisition module is connected to the power supply circuit of the photovoltaic string and is used to acquire the electrical parameters in the power supply circuit, wherein the electrical parameters are analog detection signals; The processing module, connected to the signal acquisition module, is used to convert the analog detection signal into a digital detection signal, extract features from the digital detection signal, and identify the digital detection signal as a fault signal or a normal disturbance signal generated by arcing. A switching module is connected in series in the power supply circuit of the photovoltaic string; the processing module is used to control the switching module to open in the event that the digital detection signal is a fault signal generated by arcing, so as to cut off the power supply circuit of the photovoltaic string; the processing module is also used to control the switching module to close after the arcing fault is repaired, so as to turn on the power supply circuit of the photovoltaic string.

2. The detection device for string-level DC arcing faults in photovoltaic power plants according to claim 1, characterized in that, Also includes: A frequency selection module is connected between the signal acquisition module and the processing module. The frequency selection module only allows the analog detection signal of the preset frequency band to enter the processing module.

3. The detection device for string-level DC arcing faults in photovoltaic power plants according to claim 2, characterized in that, Also includes: A signal conditioning module, connected between the frequency selection module and the processing module, is used to amplify and filter the analog detection signal.

4. The detection device for string-level DC arcing faults in photovoltaic power plants according to claim 1, characterized in that, The signal acquisition module is an arc-coupled coil.

5. The detection device for string-level DC arcing faults in photovoltaic power plants according to claim 1, characterized in that, The switching module includes a driving circuit and a switching transistor; The driving circuit is used to drive the switching transistor to disconnect according to the first control signal issued by the processing module when the digital detection signal is a fault signal generated by arcing; the driving circuit is also used to drive the switching transistor to close according to the second control signal issued by the processing module after the arcing fault is repaired.

6. The detection device for string-level DC arcing faults in photovoltaic power plants according to claim 5, characterized in that, The switching transistor is a silicon carbide metal-oxide-semiconductor field-effect transistor.

7. The detection device for string-level DC arcing faults in photovoltaic power plants according to claim 1, characterized in that, The processing module includes an analog-to-digital conversion unit, which is used to convert the analog detection signal into the digital detection signal.

8. The detection device for string-level DC arcing faults in photovoltaic power plants according to claim 1, characterized in that, Also includes: A communication module, connected to the processing module, is used to upload arcing fault information to the terminal device after the processing module identifies the digital detection signal as an arcing signal.

9. The detection device for string-level DC arcing faults in photovoltaic power plants according to claim 1, characterized in that, Also includes: A power supply module, connected to the processing module, is used to supply power to the processing module.

10. A photovoltaic system, characterized in that, include: Photovoltaic strings, inverters, and a detection device for string-level DC arcing faults in photovoltaic power plants as described in any one of claims 1-9.

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