An assembly level photovoltaic fast turn-off and a control method thereof

Abstract

The application provides a kind of assembly level photovoltaic quick shutoff and its control method, multi-source sensing unit realizes the voltage, current, temperature and arc detection of photovoltaic power station DC side;Communication control unit transmits signal by long-distance radio communication mode;Shutoff execution unit carries out high voltage quick shutoff of photovoltaic power station DC side;Master unit is connected with multi-source sensing unit, power management unit and shutoff execution unit by communication control unit, receives multi-source sensing unit detection data, and carries out local autonomous shutoff, remote instruction shutoff and power failure automatic shutoff three shutoff mode control of photovoltaic power station DC side by shutoff execution unit, multiple shutoffs are connected by LORA wireless ad hoc network, each shutoff corresponds to a photovoltaic module, and each shutoff is connected with remote monitoring platform by wireless or public network. Realize assembly level accurate monitoring, fault autonomous judgment and quick shutoff, realize the balance of low cost and high performance.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic power electronics safety technology, and in particular provides a module-level photovoltaic fast shutdown device and its control method. Background Technology

[0002] Currently, with the continuous increase in global photovoltaic installed capacity, the high-voltage safety issue on the DC side of photovoltaic power plants has become a core concern for the industry.

[0003] According to mandatory standards such as the US NEC (National Electrical Code) 2017 / 2020 and the international IEC (International Electrotechnical Commission) 62109, photovoltaic systems must be equipped with fast shutdown devices to ensure that in emergency situations (such as fire or maintenance), the DC-side voltage can be reduced to a safe range (typically ≤30V) within 30 seconds to protect the lives of maintenance personnel. Currently, the mainstream module-level shutdown solutions on the market are mainly divided into two categories: one uses PLC (Power Line Carrier) communication, which has high arc detection accuracy but suffers from high procurement costs, complex communication debugging, and high service costs; the other supports one-to-one and one-to-two deployments, offering good synchronization and a compact structure, but has drawbacks such as simplified detection functions, reliance on external signals for shutdown, and relatively high overall costs.

[0004] The closest existing technology is Chinese patent CN115276234A, which discloses a photovoltaic shutdown device with PLC communication. However, this solution has problems such as complex communication wiring and high transformation costs, and cannot meet the needs of rapid transformation of old power plants.

[0005] In addition, current circuit breakers generally have the following shortcomings: First, communication methods are limited by cabling, resulting in poor deployment flexibility and high transformation costs; second, some products lack complete status detection functions, making it impossible to achieve precise operation and maintenance at the component level; third, fault response speed is insufficient, with some products relying on host commands for shutdown, making it impossible to achieve local autonomous fault shutdown; and fourth, it is difficult to balance cost and performance, either with excessively high costs affecting large-scale deployment or reduced performance failing to meet safety standards.

[0006] Therefore, developing a safe, reliable, low-cost, easy-to-install, and fully functional module-level photovoltaic fast shutdown device has become the key to solving the current pain points in the industry. Summary of the Invention

[0007] Based on this, the present invention provides a module-level photovoltaic fast shutdown device and its control method to achieve accurate monitoring and autonomous fault judgment on the DC side of the photovoltaic power station, ensure fast and reliable shutdown under high voltage environment, improve response speed, ensure safety and reduce cost.

[0008] To achieve the above objectives, in a first aspect, the present invention provides a module-level photovoltaic fast shutdown device, comprising a multi-source sensing unit, a communication control unit, a power management unit, a shutdown execution unit, and a main control unit; the multi-source sensing unit realizes voltage, current, temperature, and arcing detection on the DC side of the photovoltaic power station; the communication control unit transmits signals using long-distance radio communication; the power management unit performs wide voltage input conversion; the shutdown execution unit performs high-voltage fast shutdown on the DC side of the photovoltaic power station; the main control unit is signal-connected to the multi-source sensing unit, the power management unit, and the shutdown execution unit through the communication control unit, receives detection data from the multi-source sensing unit, and performs three shutdown modes control on the DC side of the photovoltaic power station through the shutdown direct unit: local autonomous shutdown, remote command shutdown, and automatic shutdown in case of power failure; multiple shutdown devices are cascaded through a LoRa wireless self-organizing network, each shutdown device corresponds to one photovoltaic module, and each shutdown device is connected to a remote monitoring platform via wireless or public network.

[0009] Furthermore, the main control unit is configured to receive detection data from the multi-source sensing unit, run a fault judgment algorithm, issue a shutdown command to the shutdown execution unit, and synchronously control the communication unit to upload status information.

[0010] Furthermore, the shutdown execution unit is configured to receive a shutdown command from the main control unit, quickly disconnect the photovoltaic module from the subsequent circuit, and reduce the DC side voltage to a safe range.

[0011] Furthermore, the shutdown execution unit uses dual N-channel MOSFETs as the core switching devices and incorporates an RC snubber circuit and a freewheeling diode to suppress shutdown spikes.

[0012] Furthermore, the multi-source sensing unit includes a current detection module, a voltage detection module, and a temperature detection module. The component status sensing includes: the current detection module is configured with a mutual inductance sensor positioned close to the terminals for non-contact acquisition, collecting the photovoltaic module's output current in real time; the voltage detection module is configured with a high-voltage divider circuit, paired with an optocoupler for electrical isolation between the high-voltage and low-voltage sides, collecting the photovoltaic module's output voltage in real time; the temperature detection module's thermistor monitors the device temperature in real time, automatically triggering derating or shutdown protection if the temperature exceeds a threshold.

[0013] Furthermore, the multi-source sensing unit also includes an arc detection module, which captures arc fault signals and triggers shutdown commands based on high-frequency arc signal detection and arc extinguishing control logic.

[0014] Furthermore, the power management unit adopts a BUCK-type multi-channel step-down chip to stably convert the photovoltaic high voltage into multiple low voltage outputs, which power the main control unit, communication unit, and audible and visual alarm unit respectively. The input terminal is connected in series with a fast-blow fuse and a TVS diode to form a dual protection mechanism against overcurrent and surge.

[0015] Furthermore, the communication control unit is equipped with an integrated patch antenna to achieve wireless communication, supporting three shutdown modes: local manual shutdown, remote command shutdown, and automatic shutdown upon power failure. It constructs safety redundancy, enables communication between the shutdown unit and the local monitoring box and the remote monitoring platform, uploads detection data and fault information, and receives remote shutdown commands.

[0016] To achieve the above objectives, in a second aspect, the present invention provides a module-level photovoltaic fast shutdown control method, comprising the following steps: S1: System power-on initialization, the power management unit converts the photovoltaic high voltage into the low voltage power required by each unit, the main control unit, multi-source sensing unit and communication unit start up synchronously, and complete the self-test system process; S2: The multi-source sensing unit collects the voltage, current, temperature data and arcing signals of the photovoltaic module in real time and transmits the data to the main control unit; S3: The main control unit filters and analyzes the collected data to determine whether there are faults such as arcing, over-temperature, over-current, and over-voltage. At the same time, it uploads the real-time status data to the local monitoring box and the remote monitoring platform through the communication unit. S4: If a fault is detected, the main control unit immediately sends a shutdown command to the shutdown execution unit to control the MOS transistor to turn off quickly; if a remote shutdown command is received, the main control unit also triggers the shutdown execution unit to shut down; in the event of power failure, a capacitor energy storage circuit is used, and when power fails, the capacitor discharges to drive the gate of the MOS transistor to achieve shutdown. S5: After troubleshooting, the circuit breaker can be restored to normal operation and re-collect data and upload status by local manual reset or remote command reset.

[0017] S6: Multiple circuit breakers are cascaded through a LoRa wireless self-organizing network and output to the string combiner. Each circuit breaker corresponds to a photovoltaic module, enabling independent monitoring and shutdown at the module level. The status data of all circuit breakers are aggregated to the local monitoring box and then transmitted to the remote monitoring platform via wireless or public network, enabling centralized management, fault location and remote operation and maintenance of large-scale power plants.

[0018] Among them, the single parameter threshold verification is as follows: First, the basic threshold verification is performed on the four parameters of voltage, current, temperature, and arcing signal, and abnormal states are marked: voltage abnormality is marked as component output voltage <10V or >60V; current abnormality is marked as current mutation rate >30%; temperature abnormality is marked as MOSFET temperature >85℃ warning or >100℃ fault; arcing abnormality is marked as the proportion of high-frequency energy output by the arcing detection module exceeds the threshold. Multi-parameter fusion judgment: Based on the anomaly flag of a single parameter, multi-parameter fusion judgment is performed to eliminate the possibility of misjudgment by a single parameter and confirm the true fault type: arcing fault is when arcing abnormality + current abnormality + voltage abnormality are met simultaneously; over-temperature fault is when temperature fault + current <5A are met simultaneously; component fault is when voltage abnormality + current abnormality are met simultaneously; warning fault is when only temperature warning or only current abnormality is detected. Tiered response execution: Different response strategies are executed according to the severity of the fault: Level 1 emergency faults trigger immediate shutdown; Level 2 early warning faults start a 100ms delay count, and if the abnormality continues, shutdown is triggered; the fault count is reset to zero in normal state.

[0019] The arc extinguishing control logic of S4 specifically includes: Fast gate discharge: The main controller uses the MCP1416T driver chip to quickly extract the stored charge from the gate of the MOSFET with a maximum sink current capability of 2A, compressing the turn-off time of the MOSFET to less than 10ns and quickly cutting off the power supply current for arcing faults. Peak suppression and freewheeling: During the turn-off process, the RC absorption circuit (100Ω+100nF) quickly absorbs the voltage spikes generated when the MOSFET is turned off, preventing the spike voltage from breaking down the device or causing a new arc; at the same time, the freewheeling diode FR107 provides a freewheeling path for the residual current in the line, allowing the residual energy of the arc to be released quickly and accelerating the extinction of the arc. Redundant arc extinguishing during power failure: If the system loses power during a fault, the energy storage capacitor of the shutdown execution unit will automatically discharge to provide a driving voltage for the gate of the MOSFET, automatically turning off the MOSFET, and completing the arc extinguishing without the need for main control power supply. Compared with existing technologies, the technical advantages of the module-level photovoltaic fast shutdown device and its control method provided by this invention are at least reflected in the following aspects: Firstly, it integrates triple detection of voltage, current, and temperature, as well as arc detection functions, to achieve precise monitoring at the component level and autonomous fault diagnosis; it also optimizes the shutdown execution module to ensure rapid and reliable shutdown under high-voltage conditions and improve response speed. Secondly, it enables wireless communication without additional wiring, reducing deployment and upgrade costs and improving networking flexibility; while controlling costs, it ensures core security performance, meets relevant international and domestic standards, and achieves a balance between low cost and high performance. Attached Figure Description

[0020] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The accompanying drawings, which are included to provide a further understanding of the invention and constitute a part of this application, illustrate exemplary embodiments of the invention and, together with their descriptions, serve to explain the invention and do not constitute an undue limitation thereof.

[0021] Figure 1This is a block diagram of the overall structure of a photovoltaic fast shutdown device; Figure 2 This is the main circuit diagram of the circuit breaker; Figure 3 This is a schematic diagram of the arc detection principle; Figure 4 This is a flowchart of the shutdown process; Figure 5 This is a diagram showing the circuit breaker connection. Figure 6 This is a hardware architecture design diagram of the shutdown device. Detailed Implementation

[0022] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use.

[0023] Addressing the technical pain points of existing photovoltaic module-level fast shutdown devices, such as high cost, complex communication debugging, incomplete detection functions, untimely shutdown response, and poor deployment flexibility, this invention optimizes the hardware architecture, integrates comprehensive detection functions, and adopts wireless communication. It employs a combined architecture of multi-source sensing units, wireless communication, and triple shutdown, integrating voltage, current, and temperature detection, as well as arc detection. It features three shutdown modes: local autonomous shutdown, remote command shutdown, and power failure shutdown. Furthermore, it utilizes wireless communication (such as LoRa), eliminating the need for additional wiring and enabling independent monitoring and networking at the module level. This achieves the technical goals of low cost, high reliability, and convenient operation and maintenance, making it directly applicable to mass production and adaptable to the safety protection and operation and maintenance needs of various photovoltaic power plants, aligning with the global photovoltaic industry's safety development trends.

[0024] In its implementation, this invention provides a module-level photovoltaic fast shutdown device based on an STM32 microcontroller, comprising a main control unit, a shutdown execution unit, a multi-source sensing unit, a power management unit, and a communication control unit. The main control unit uses an STM32G431 chip to coordinate the collaborative work of all units. The shutdown execution unit achieves high-voltage fast shutdown based on dual MOSFETs. The multi-source sensing unit performs triple detection of voltage, current, and temperature, as well as arc detection. The power management unit uses a BUCK step-down chip to achieve wide voltage input conversion. The communication unit uses LORA (Long-Range Radio) wireless communication, eliminating the need for additional wiring. The device achieves three shutdown modes: local autonomous shutdown, remote command shutdown, and automatic shutdown in case of power failure, combining monitoring, early warning, and convenient operation and maintenance. It is suitable for the DC side of photovoltaic power plants, enabling rapid shutdown, status monitoring, and fault early warning of photovoltaic modules, ensuring the safe and stable operation of photovoltaic power plants.

[0025] The following is a complete description of the module-level photovoltaic fast shutdown device based on an STM32 main control proposed in this invention, and the specific implementation method is as follows: Overall Structure: The core of this shutdown unit consists of a main control unit, a shutdown execution unit, a multi-source sensing unit, a power management unit, and a communication control unit. These units work together to achieve full functionality including shutdown, detection, communication, and fault reporting. (See the overall architecture diagram below.) Figure 1 As shown.

[0026] Specific design and implementation of each unit: Main control unit: The STM32G431 is used as the core controller. Based on the ARM Cortex-M4 core, it integrates a high-speed 12-bit ADC and rich peripheral interfaces. It has sufficient computing power and controllable power consumption, and supports complex detection and control algorithms. Its core function is to receive detection data from multi-source sensing units, run fault judgment algorithms, send shutdown instructions to the shutdown execution unit, and synchronously control the communication unit to upload status information. It is the core control center of the entire shutdown device.

[0027] The shutdown execution unit uses dual N-channel MOSFETs (IPP023N10N5) as the core switching device, featuring low on-resistance and low loss. Combined with a dedicated driver chip (MCP1416T), it achieves nanosecond-level switching speeds. An RC snubber circuit and freewheeling diode are designed to suppress shutdown spikes and ensure safe shutdown under 1500V DC high voltage. Its core function is to receive shutdown commands from the main control unit, quickly disconnect the photovoltaic modules from subsequent circuits, and reduce the DC-side voltage to a safe range. Figure 2 As shown. Power-off details: This unit is equipped with a capacitor energy storage circuit. When the system is working normally, the capacitor charges and stores energy; when the system loses power, the capacitor automatically discharges to drive the gate of the MOSFET, turning off the MOSFET, thus achieving automatic power-off without the need for main control power supply, ensuring safety redundancy.

[0028] Multi-source sensing unit: Composed of current detection module, voltage detection module, temperature detection module and arc detection module, to achieve comprehensive sensing of component status. (1) Current detection: The GPCT01Z mutual inductance sensor is used for non-contact acquisition. It is located close to the terminal to improve the detection accuracy and anti-interference ability, and to collect the output current of the photovoltaic module in real time. (2) Voltage detection: A high voltage divider circuit of R1 (100kΩ) + R2 (3.3kΩ) is used, with optocoupler isolation, to adapt to a 1500V DC system, ensuring electrical isolation between the high voltage side and the low voltage side, and to collect the output voltage of the photovoltaic module in real time; (3) Temperature detection: The NTC thermistor is in close contact with the power MOSFET to monitor the device temperature in real time. If the temperature exceeds the threshold, it will automatically trigger derating or shutdown protection. (4) Arc detection: Based on the high-frequency arc signal detection and arc extinguishing control logic of the STM32 main control, the arc fault signal is captured by high-frequency sampling and spectrum analysis, triggering the shutdown instruction. It is connected to the PB4 (ADC_IN4) pin of the main control. The circuit schematic of this module is as follows. Figure 3 As shown.

[0029] Power Management Unit: Employs the BUCK-type XL7015 80V multi-channel step-down chip, which can stably convert photovoltaic high voltage (100V-1500VDC) into three outputs: 5V, 3.3V, and 12V, providing reliable power to core components such as the main control unit, communication unit, and audible and visual alarm unit. The input terminal is connected in series with a fast-blow fuse and a TVS diode to form a dual overcurrent and surge protection mechanism, effectively preventing high voltage surges from damaging internal components and ensuring long-term stable operation of the shutdown unit.

[0030] Communication control unit: Integrated patch antenna enables wireless communication (LORA communication is preferred), requiring no additional wiring and allowing for flexible deployment; reserved arc extinguishing signal interface, supporting three shutdown modes: local manual shutdown, remote command shutdown, and automatic shutdown upon power failure, building safety redundancy; its core function is to enable communication between the shutdown unit and the local monitoring box and remote monitoring platform, uploading detection data and fault information, and receiving remote shutdown commands.

[0031] Fault diagnosis and arc extinguishing control algorithm implementation: The algorithm uses a 10ms detection cycle to cyclically collect voltage, current, temperature, and arcing signals from multi-source sensing units. After three layers of logic processing, it outputs fault diagnosis results and shutdown instructions. The overall execution flow is as follows: system power-on initialization → multi-source data acquisition and filtering → single-parameter threshold verification (initial judgment of potential faults) → multi-parameter fusion judgment (confirmation of actual faults) → graded response and autonomous shutdown → local recording of fault information + LoRa upload.

[0032] First layer: Single-parameter threshold verification Raw data from four sensing channels—voltage, current, temperature, and arcing—is filtered and threshold range verified to quickly identify obvious anomalies and preliminarily determine potential faults, providing a foundation for subsequent integrated judgment. This level allows for flexible threshold configuration based on the rated parameters of the photovoltaic modules (e.g., 550W modules) to adapt to different specifications of photovoltaic modules. Specific thresholds and fault judgment conditions are shown in the table below: Component DC voltage 100kΩ + 3.3kΩ voltage divider circuit 18V-48V Voltage <10V or voltage >60V Component open circuit, short circuit, abnormal Component operating current GPCT01Z Mutual Inductance Sensor 0A-15A Current surge rate ≥30% or sustained 0A >500ms Arcing precursors, component failure MOSFET temperature NTC thermistor -40℃-85℃ Temperature > 100℃ or temperature rise ≥ 20℃ / min Overheating fault, abnormal heat dissipation High-frequency arcing signal Arc detection module High frequency amplitude < set threshold High-frequency amplitude duration > threshold ≥ 5ms Arc fault Second layer: Multi-parameter fusion judgment (core innovation, avoiding false triggering) This is the core innovation of the algorithm. Addressing the issue of strong electromagnetic interference and load fluctuations in photovoltaic power plants easily leading to misjudgments of single parameters, it employs a combination of "logical AND" and "logical OR" judgments. Only when multiple related parameters are simultaneously in an abnormal state is it determined to be a "real fault," completely resolving the pain point of misjudgment in single parameter threshold judgments. This level focuses on the most critical photovoltaic shutdown faults: arcing faults, over-temperature faults, and module faults, and designs a dedicated integrated judgment logic, as follows: like Figure 3 As shown, a moving average filter is applied to each data stream to eliminate instantaneous fluctuations caused by electromagnetic interference. The data is then compared with a preset threshold. If the threshold is exceeded, the parameter is marked as "abnormal" and proceeds to the next level of fusion judgment. If all parameters are within the threshold range, the data is judged to be operating normally and the data collection continues in a loop.

[0033] (1) Arcing fault fusion judgment (highest priority) Arcing faults are emergency faults in photovoltaic power plants and can easily cause fires. Accurate judgment is required to avoid omissions and misjudgments. The judgment logic is: Arcing fault = abnormal high-frequency arcing signal AND current mutation rate ≥ 30% AND voltage fluctuation amplitude ≥ 10%. Judgment principle: An abnormal arcing signal alone may be electromagnetic interference, a current mutation alone may be load fluctuation, and a voltage fluctuation alone may be system start-up and shutdown. Only when all three conditions are met simultaneously can it be confirmed as a real arcing fault, reducing the false trigger rate to below 0.1%.

[0034] (2) Fusion judgment of over-temperature fault Over-temperature faults need to be distinguished between "over-temperature caused by MOSFET failure" and "temperature rise caused by normal operation with high current". The judgment logic is: over-temperature fault = temperature exceeds threshold (>100℃) AND module operating current <5A (no high current load). Judgment principle: When photovoltaic modules are operating normally, high current will cause a slight temperature rise of MOSFET, which is a normal phenomenon; only when the MOSFET temperature still exceeds the threshold when there is no high current load is it judged as MOSFET failure or heat dissipation system abnormality, so as to avoid accidental shutdown during normal operation.

[0035] (3) Component fault fusion judgment Component failures need to be distinguished from "component's own open circuit or short circuit" and "normal system start-up and shutdown". The judgment logic is: component failure = voltage abnormality AND current abnormality AND abnormal state lasting ≥100ms. Judgment principle: during normal system start-up and shutdown, there will be instantaneous voltage and current abnormalities, while component failure will cause voltage and current to be abnormal simultaneously and continuously. By combining "dual parameter abnormality + time delay", misjudgment of system start-up and shutdown is avoided.

[0036] Third layer: Hierarchical response and autonomous shutdown (algorithm execution layer) Based on the severity and urgency of the faults, they are categorized into Level 1 Emergency Faults, Level 2 Warning Faults, and Level 3 Minor Anomalies. Differentiated response strategies are designed to achieve the goals of "precise shutdown, safety redundancy, and ensuring continuous system operation." Simultaneously, local recording and LoRa wireless uploading of fault information are triggered, providing a basis for power plant operation and maintenance. The specific tiered response logic is shown in the table below: Level 1 (Emergency) Arcing fault, severe overheating, component short circuit The shutdown execution unit is immediately triggered, controlling the MOSFET to quickly shut down within 10ms, thus cutting off the power link of the photovoltaic module. Immediately upload fault type + location via LoRa Level 2 (Warning) Temperature slightly higher than normal (85℃~100℃), current slightly abnormal Record fault data and continuously monitor in a loop. If the abnormal state is not recovered within ≥10 seconds, trigger shutdown; if it is recovered, cancel the warning. Upload abnormal data every 5 seconds until recovery. Level 3 (Mild) Slight voltage fluctuations and brief communication interruptions Fault logs are recorded locally only, without triggering shutdown, ensuring the normal operation of photovoltaic modules. Logs are uploaded only during system self-checks, not in real time. The three-layer autonomous fault diagnosis and arc extinguishing control algorithm built into this invention can be directly run on STM32G431. The control method for the provided module-level photovoltaic fast shutdown device includes the following steps: S1: System power-on initialization. The power management unit converts the photovoltaic high voltage to the low voltage required by each unit. The main control unit, multi-source sensing unit, and communication unit start up synchronously, completing the self-test system process. The workflow is as follows: Figure 4 As shown; S2: The multi-source sensing unit collects the voltage, current, temperature data and arcing signals of the photovoltaic module in real time, and transmits the data to the main control unit through the ADC interface; S3: The main control unit filters and analyzes the collected data to determine whether there is a fault (arc, over-temperature, over-current, over-voltage, etc.), and uploads the real-time status data to the local monitoring box and the remote monitoring platform through the communication unit. S4: If a fault is detected, the main control unit immediately sends a shutdown command to the shutdown execution unit to control the MOS transistor to turn off quickly; if a remote shutdown command is received, the main control unit also triggers the shutdown execution unit to shut down; in the event of power failure, a capacitor energy storage circuit is used, and when power fails, the capacitor discharges to drive the gate of the MOS transistor to achieve shutdown. S5: After troubleshooting, the circuit breaker can be restored to normal operation and re-collect data and upload status by local manual reset or remote command reset.

[0037] S6: Multiple circuit breakers described in this invention are cascaded through a LORA wireless self-organizing network and output to the string combiner. Each circuit breaker corresponds to a photovoltaic module, realizing independent monitoring and shutdown at the module level. After networking, the status data of all circuit breakers are aggregated to the local monitoring box and then transmitted to the remote monitoring platform via wireless or public network to realize centralized management, fault location and remote operation and maintenance of large-scale power plants.

[0038] Figure 5 This diagram illustrates the connection of the power-off switches. Each photovoltaic module corresponds to an independent power-off switch (power-off switch 1 / 2 / n). The power-off switches are connected to the module's PV+ / PV- terminals via terminals + / - to achieve module-level power control. Loads (electrical appliances): The power-off switches' output terminals OUT+ / OUT- are cascaded and connected to the loads (such as combiner boxes, inverters, etc.) to complete power output.

[0039] Figure 6 The hardware architecture features a single-path design, allowing for precise control of each photovoltaic module and ensuring that a fault does not affect other parts of the string. It integrates current, voltage, and temperature detection for comprehensive module status monitoring. Triple shutdown logic (local fault, remote command, power outage) plus robust hardware protection circuitry further enhances its capabilities. Wireless communication eliminates the need for wiring, and the use of universal components makes it suitable for large-scale power plant retrofitting.

[0040] The innovations of the module-level photovoltaic fast shutdown device and its control method provided by this invention include: Innovative Communication Architecture: This invention employs LoRa wireless communication with an integrated patch antenna, eliminating the need for additional wiring, allowing for flexible deployment and low modification costs, while also avoiding interference issues caused by wiring.

[0041] Most mainstream products in the current technology use PLC (power line carrier) communication or wireless / wired hybrid communication, which rely on wiring or dedicated signal generators. The debugging is complicated, the transformation cost is high, and they are easily affected by line interference.

[0042] Innovation in Topology: Compared to mainstream products in existing technologies, which are mostly highly integrated one-to-one or one-to-two solutions where components and shutdown devices are bound together, resulting in poor flexibility and high customization difficulty, this invention is a single-channel independent shutdown device that can be flexibly combined, adapted to any component layout, and has strong customization capabilities. It also enables independent monitoring and shutdown at the component level, allowing for precise location of faulty components.

[0043] Integrated Sensing and Control: Compared to existing products with simplified detection functions, focusing only on shutdown execution or requiring additional monitoring modules, and with fault diagnosis relying on the host and experiencing high response latency, this invention integrates voltage, current, and temperature triple detection as well as arc detection functions. It requires no additional configuration, enabling comprehensive perception of component status. Furthermore, it incorporates a built-in fault diagnosis algorithm, allowing for autonomous shutdown triggering without host dependence, resulting in faster response times.

[0044] Cost and performance balance: Current products present a significant performance / cost contradiction: either they use high-end dedicated components, resulting in high procurement costs and difficulty in scaling up; or they reduce hardware configuration, leading to compromises in core safety performance such as shutdown response speed and detection accuracy. This invention selects general-purpose, low-cost components and optimizes circuit design and algorithms to control hardware costs while ensuring core safety performance such as shutdown response speed and detection accuracy, achieving a balance between low cost and high performance, making it more suitable for large-scale deployment.

[0045] This invention provides a module-level photovoltaic (PV) fast shutdown device and its control method, which can be widely applied to various PV power plants, including distributed PV power plants, centralized PV power plants, and residential PV systems. Specific application products include: finished module-level PV shutdown devices, PV power plant safety protection systems, PV module operation and maintenance monitoring equipment, and PV combiner box-related shutdown devices. It is suitable for all scenarios requiring rapid shutdown, status monitoring, and fault early warning of PV modules. A specific application example: A PV power plant operation and maintenance company is responsible for the operation and maintenance of a 10MW distributed PV power plant. The original PV system of this power plant was not equipped with a module-level fast shutdown device, did not meet the latest safety standards, and suffered from high operation and maintenance difficulty, slow fault location, and significant safety hazards. By adopting the module-level PV fast shutdown device and its control method described in this invention, the operation and maintenance company does not need to carry out large-scale modifications to the original lines. The shutdown device is connected to each PV module through a wireless self-organizing network, achieving independent module-level monitoring and shutdown.

[0046] Cost-Controllable: Utilizing general-purpose, low-cost core components and optimized circuit design, hardware costs are significantly lower than existing mainstream products. Furthermore, no additional wiring is required, reducing deployment and upgrade costs and making it suitable for large-scale deployment. Flexible Deployment: Employing wireless communication, it eliminates the need for DC cable wiring. Individual circuits can be flexibly combined to adapt to any photovoltaic module layout. It also seamlessly integrates with existing mainstream photovoltaic monitoring platforms, reducing user integration costs. Convenient Operation and Maintenance: Supports precise module-level monitoring and remote operation and maintenance, enabling rapid fault location and early warning of potential risks such as line aging, improving the overall reliability of the power station. Comprehensive Functions: Integrates voltage, current, and temperature triple detection and arc detection functions, achieving comprehensive module status awareness. It also features IoT monitoring, edge computing, and active shutdown capabilities, meeting the precise module-level operation and maintenance needs of photovoltaic power stations.

[0047] Through the above embodiments, the present invention adopts a triple shutdown mode of local autonomous shutdown, remote command shutdown, and power failure shutdown. Under 100-1500V DC input, the shutdown response time is ≤10ms; in 1000 arcing tests, the detection accuracy is ≥99%, which can quickly reduce the DC side voltage to a safe range, meet NEC 2017 / 2020 and IEC 62109 standards, and effectively protect the life safety of photovoltaic power plant operation and maintenance personnel.

[0048] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. The above drawings and specific embodiments are for illustrative purposes only, and this invention is not limited thereto. Minor modifications to this invention within the inventive spirit and scope defined by the claims of this invention all fall within the protection scope of this invention.

Claims

1. A module-level photovoltaic fast shutdown device, characterized in that, It includes a multi-source sensing unit, a communication control unit, a power management unit, a shutdown execution unit, and a main control unit; The multi-source sensing unit enables the detection of voltage, current, temperature, and arcing on the DC side of the photovoltaic power station; The communication control unit transmits signals using long-distance radio communication. The power management unit performs wide voltage input conversion; The shutdown execution unit performs rapid high-voltage shutdown on the DC side of the photovoltaic power station; The main control unit is connected to the multi-source sensing unit, power management unit and shutdown execution unit through the communication control unit. It receives detection data from the multi-source sensing unit and performs three shutdown modes control on the DC side of the photovoltaic power station through the shutdown execution unit: local autonomous shutdown, remote command shutdown and automatic shutdown in case of power failure. Multiple power switches are cascaded via a LoRa wireless self-organizing network. Each power switch corresponds to a photovoltaic module, and each power switch is connected to a remote monitoring platform via wireless or public network.

2. The module-level photovoltaic fast shutdown device according to claim 1, characterized in that, The main control unit is configured to receive detection data from the multi-source sensing unit, run a fault judgment algorithm, send a shutdown command to the shutdown execution unit, and synchronously control the communication unit to upload status information. The fault judgment algorithm includes a three-layer architecture of single-parameter threshold verification, multi-parameter fusion judgment, and hierarchical response execution, and completes fault judgment and shutdown command issuance through local multi-source sensing data.

3. The module-level photovoltaic fast shutdown device according to claim 1, characterized in that, The shutdown execution unit is configured to receive the shutdown command from the main control unit, quickly disconnect the photovoltaic module from the subsequent circuit, and reduce the DC side voltage to a safe range. The shutdown execution unit uses a dual-channel N-channel MOSFET as the core switching device and sets up an RC snubber circuit and a freewheeling diode to suppress shutdown spikes.

4. The module-level photovoltaic fast shutdown device according to claim 1, characterized in that, The multi-source sensing unit includes a current detection module, a voltage detection module, and a temperature detection module, and performs component status sensing including: The current detection module is equipped with a mutual inductance sensor located close to the terminal for non-contact acquisition, and collects the output current of the photovoltaic module in real time. The voltage detection module is equipped with a high-voltage divider circuit and an optocoupler to provide electrical isolation between the high-voltage side and the low-voltage side, and to collect the output voltage of the photovoltaic module in real time. The thermistor in the temperature detection module monitors the device temperature in real time, and automatically triggers derating or shutdown protection when the temperature exceeds the threshold.

5. The module-level photovoltaic fast shutdown device according to claim 4, characterized in that, The multi-source sensing unit also includes an arc detection module, which captures arc fault signals and triggers a shutdown command based on high-frequency arc signal detection and arc extinguishing control logic. The hardware acquisition link of the arc detection module uses a high-frequency current transformer to collect the line current signal in a non-contact manner. The low-frequency power frequency and inverter switching noise are filtered by a second-order RC bandpass filter circuit, and the signal gain is amplified by an operational amplifier. Finally, electrical isolation is achieved by a high-speed optocoupler. The main controller collects the signal at an ultra-high-speed sampling frequency to meet the Nyquist sampling requirements of the arc high-frequency signal.

6. The module-level photovoltaic fast shutdown device according to claim 1, characterized in that, The power management unit uses a BUCK-type multi-channel step-down chip to stably convert the photovoltaic high voltage into multiple low voltage outputs, which power the main control unit, communication unit, and audible and visual alarm unit respectively. The input terminal is connected in series with a fast-blow fuse and a TVS diode to form a dual protection mechanism against overcurrent and surge.

7. The module-level photovoltaic fast shutdown device according to claim 1, characterized in that, The communication control unit is equipped with an integrated patch antenna to achieve wireless communication, supports three shutdown modes: local manual shutdown, remote command shutdown, and automatic shutdown upon power failure, constructs safety redundancy, and enables communication between the shutdown unit and the local monitoring box and the remote monitoring platform, uploading detection data and fault information, and receiving remote shutdown commands.

8. A module-level photovoltaic fast shutdown control method, characterized in that, Including the following steps: S1: System power-on initialization, the power management unit converts the photovoltaic high voltage into the low voltage power required by each unit, the main control unit, multi-source sensing unit and communication unit start up synchronously, and complete the self-test system process; S2: The multi-source sensing unit collects the voltage, current, temperature data and arcing signals of the photovoltaic module in real time, and transmits the data to the main control unit to realize autonomous fault judgment; S3: The main control unit filters and analyzes the collected data to determine whether there are faults such as arcing, over-temperature, over-current, and over-voltage. At the same time, it uploads the real-time status data to the local monitoring box and the remote monitoring platform through the communication unit. S4: If a fault is detected, the main control unit immediately sends a shutdown command to the shutdown execution unit to control the MOSFET to turn off quickly; If a remote shutdown command is received, the main control unit will also trigger the shutdown execution unit to shut down; in the event of power failure, a capacitor energy storage circuit is used, and when power fails, the capacitor discharges to drive the gate of the MOS transistor to achieve shutdown; S5: After troubleshooting, the shut-off device will resume normal operation and re-collect data and upload status by local manual reset or remote command reset. S6: Multiple shutdown devices are cascaded through a LORA wireless self-organizing network and output to the string combiner. Each shutdown device corresponds to a photovoltaic module, realizing independent monitoring and shutdown at the module level. The status data of all circuit breakers are aggregated to the local monitoring box and then transmitted to the remote monitoring platform via wireless or public network, enabling centralized management, fault location and remote operation and maintenance of large-scale power plants.

9. The module-level photovoltaic fast shutdown control method according to claim 8, characterized in that, S2 include: Single-parameter threshold verification: First, perform basic threshold verification on four parameters: voltage, current, temperature, and arcing signal, and mark abnormal states: voltage abnormality is marked as component output voltage <10V or >60V; current abnormality is marked as current mutation rate >30%; temperature abnormality is marked as MOSFET temperature >85℃ warning or >100℃ fault; arcing abnormality is marked as the proportion of high-frequency energy output by the arcing detection module exceeds the threshold. Multi-parameter fusion judgment: Based on the anomaly flag of a single parameter, multi-parameter fusion judgment is performed to eliminate the possibility of misjudgment by a single parameter and confirm the true fault type: arcing fault is when arcing abnormality + current abnormality + voltage abnormality are met simultaneously; over-temperature fault is when temperature fault + current <5A are met simultaneously; component fault is when voltage abnormality + current abnormality are met simultaneously; warning fault is when only temperature warning or only current abnormality is detected. Tiered response execution: Different response strategies are executed according to the severity of the fault: Level 1 emergency faults trigger immediate shutdown; Level 2 early warning faults start a delay count, and if the abnormality continues, shutdown is triggered; the fault count is reset to zero in normal state.

10. The module-level photovoltaic fast shutdown control method according to claim 8, characterized in that, The arc extinguishing control logic of S4 specifically includes: Fast gate discharge: The main controller, through the driver chip, can quickly extract the stored charge from the gate of the MOSFET with a maximum sinking current of 2A, thereby compressing the turn-off time of the MOSFET and quickly cutting off the power supply current for arcing faults. Peak suppression and freewheeling: During the turn-off process, the RC snubber circuit quickly absorbs the voltage spikes generated when the MOSFET is turned off, preventing the spike voltage from breaking down the device or causing a new arc; at the same time, the freewheeling diode provides a freewheeling path for the residual current in the line, allowing the residual energy of the arc to be released quickly and accelerating the extinction of the arc. Redundant arc extinguishing during power failure: If the system loses power during a fault, the energy storage capacitor of the shutdown execution unit will automatically discharge to provide a driving voltage for the gate of the MOSFET, automatically turning off the MOSFET, and completing the arc extinguishing without the need for main control power supply.

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