Photovoltaic system direct current cable ground short circuit automatic removal control alarm device and photovoltaic power generation system

Abstract

The utility model relates to photovoltaic power generation technical field, concretely relates to a kind of photovoltaic system direct current cable grounding short-circuit automatic removal control alarm device and photovoltaic power generation system, to solve the technical problem that photovoltaic system direct current cable grounding short-circuit fault is difficult to safely, automatically remove.This device includes: setting on the line control direct current circuit breaker between photovoltaic group string and inverter;And programmable controller.Communication interface of programmable controller is connected with the communication interface of inverter, to obtain the operating data of inverter;The control output end of programmable controller is connected with the control end of line control direct current circuit breaker.When programmable controller judges that there is grounding short-circuit fault according to the operating data obtained, it automatically outputs disconnecting instruction to line control direct current circuit breaker, to cut off fault circuit.The utility model effectively avoids the huge risk of manual live operation, significantly improves the operation safety and reliability of photovoltaic system.

Description

Technical Field

[0001] This utility model relates to the field of photovoltaic power generation technology, specifically to a photovoltaic system DC cable grounding short circuit automatic disconnection control alarm device and a photovoltaic power generation system. Background Technology

[0002] In distributed or centralized photovoltaic power generation systems, the DC cables of photovoltaic strings are typically collected and connected to inverters or DC combiner boxes via cable trays, conduits, or underground installations. However, during long-term operation, these DC cables may suffer insulation damage or performance degradation due to initial quality issues, improper construction, or environmental factors, leading to ground faults between the positive or negative terminals.

[0003] When such faults occur, conventional protection devices often cannot effectively isolate the fault because the short circuit point is located at the input front end of the inverter or combiner box. In this situation, the short circuit current generates high temperatures, which can easily ignite cables and even cause fires, posing a serious threat to the safety of the entire power station. Traditional handling methods rely on manual operation by maintenance personnel, such as disconnecting the MC4 connector or cutting the cable with insulated tools. These operations are not only extremely risky, easily generating dangerous DC arcs that can cause electric shock or burns to operators, but also, in cases where cable markings are unclear or damaged, maintenance personnel cannot quickly and accurately locate the faulty string, thus delaying valuable handling time and potentially causing the fault to expand further.

[0004] Therefore, there is an urgent need for a solution that can automatically and safely disconnect grounding short-circuit faults and provide rapid alarm prompts to ensure the safe and stable operation of photovoltaic systems and the personal safety of maintenance personnel. Utility Model Content

[0005] In order to solve the above-mentioned problems in the prior art, namely the difficulty in safely and automatically disconnecting DC cable grounding short circuit faults in photovoltaic systems, this utility model provides a photovoltaic system DC cable grounding short circuit automatic disconnection control alarm device and photovoltaic power generation system.

[0006] The first aspect of this utility model provides an automatic disconnection control and alarm device for grounding short circuits in DC cables of photovoltaic systems, comprising:

[0007] A line-controlled DC circuit breaker, which is installed in the DC circuit between the photovoltaic string and the inverter; and

[0008] A programmable logic controller (PLC), the PLC including a communication interface connected to the communication interface of the inverter, and a control output terminal connected to the control terminal of the line-controlled DC circuit breaker;

[0009] The programmable controller is configured to: determine whether a ground short circuit fault exists based on the operating data obtained from the inverter, and when a ground short circuit fault is determined to exist, output a disconnect command to the line-controlled DC circuit breaker via the control output terminal.

[0010] Furthermore, the line-controlled DC circuit breaker is a bipolar circuit breaker, with its two poles connected in series in the positive and negative circuits of the photovoltaic string, respectively.

[0011] Furthermore, it also includes an audible and visual alarm; the programmable controller is also provided with an alarm output terminal, which is electrically connected to the audible and visual alarm.

[0012] Furthermore, it also includes a touch screen; the touch screen is communicatively connected to the programmable controller.

[0013] Furthermore, it also includes a switch; both the programmable controller and the touch screen are equipped with Ethernet interfaces and are connected to the switch via the Ethernet interfaces.

[0014] Furthermore, the switch is also equipped with an external communication interface for connecting remote monitoring terminals.

[0015] Furthermore, the communication interface of the programmable controller is an RS485 communication interface, and it is connected to the inverter through this RS485 communication interface.

[0016] Furthermore, it also includes a first control box for accommodating the line-controlled DC circuit breaker; the first control box is located between the DC output terminal of the photovoltaic string and the DC trunk cable to the inverter, for providing short-circuit protection for the DC trunk cable.

[0017] Furthermore, it also includes a second control box for accommodating the programmable controller; the second control box is mounted on the housing of the inverter, or on a support structure adjacent to the inverter.

[0018] In a second aspect, this utility model provides a photovoltaic power generation system, comprising:

[0019] Photovoltaic strings;

[0020] Inverters; and

[0021] The photovoltaic system DC cable grounding short circuit automatic disconnection control alarm device as described in the first aspect.

[0022] The beneficial effects of this utility model are:

[0023] This invention achieves automatic identification and isolation of ground faults by setting up a linkage structure between a programmable logic controller (PLC) and a line-controlled DC circuit breaker. When the inverter detects abnormal operating data, the PLC can automatically issue a disconnect command to the line-controlled DC circuit breaker located at the front end of the fault, thereby replacing the traditional high-risk manual operation of disconnecting connectors or cutting cables by maintenance personnel. This fundamentally avoids the risks of DC arcs, electric shocks, and burns that may occur during operation, greatly ensuring the personal safety of maintenance personnel.

[0024] Because the line-controlled DC circuit breaker is directly installed on the DC circuit between the photovoltaic string and the inverter, it can accurately isolate the fault source at the first moment of occurrence. This rapid and automatic disconnection mechanism effectively prevents the continued action of the ground fault current, thereby preventing fire accidents caused by cable overheating, avoiding further expansion of the fault range, protecting key equipment such as photovoltaic cables and inverters, and improving the operational reliability and asset security of the entire photovoltaic power generation system.

[0025] The core of this invention, the programmable controller (PPC), is based on real-time operating data acquired from the inverter for fault diagnosis. This structural design automates and intelligently diagnoses and responds to faults. Compared to the time-consuming process of traditional manual troubleshooting and locating faulty strings, this solution can react instantly and perform isolation operations after a fault occurs, greatly shortening the time from fault occurrence to isolation, creating conditions for subsequent maintenance work, and improving overall fault handling efficiency. Attached Figure Description

[0026] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0027] Figure 1 This is a schematic diagram of the overall connection structure of a photovoltaic system DC cable grounding short circuit automatic disconnection control alarm device according to the present invention.

[0028] 1-Photovoltaic string; 2-Photovoltaic string positive terminal; 3-Photovoltaic string negative terminal; 4-Wire-controlled DC circuit breaker; 5-Inverter; 6-PV positive terminal; 7-PV negative terminal; 8-Inverter RS485 communication A+ terminal; 9-Inverter RS485 communication B- terminal; 10-PLC; 11-Programmable controller RS485 communication A+ terminal; 12-Programmable controller RS485 communication B- terminal; 13-Programmable controller output common terminal; 14-AC 220V neutral wire; 15-AC 220V live wire; 16-Programmable controller output Y1 terminal; 17-First network cable; 18-Switch; 19-Second network cable; 20-Touch screen; 21-Third network cable; 22-Audible and visual alarm; 23-Programmable controller output Y2 terminal. Detailed Implementation

[0029] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0031] Please see the appendix Figure 1 This utility model provides an automatic disconnection control alarm device for DC cable grounding short circuit in a photovoltaic system. The device includes a line-controlled DC circuit breaker 4 installed between the photovoltaic string 1 and the inverter 5, and a programmable controller 10 as the control center.

[0032] In practice, the photovoltaic string 1 can be an array composed of photovoltaic modules of various materials, models, or specifications, and its quantity can be flexibly determined according to the actual site conditions. The inverter 5 can be a string inverter commonly used in distributed photovoltaic projects, or a centralized inverter used in large-scale centralized power plants.

[0033] The programmable logic controller 10 (PLC) and the touch screen 20 are not limited to specific brands or models; any commercially available product with the corresponding functions can be used. In addition to the overload and short-circuit protection functions of a conventional circuit breaker, the core of the line-controlled DC circuit breaker 4 lies in its built-in trip coil that can receive and be controlled by external electrical signals.

[0034] The circuit breaker 4 is connected in series between the DC output circuit of the photovoltaic string 1 and the DC input terminal (i.e., PV positive terminal 6 and PV negative terminal 7) of the inverter 5. The programmable controller 10 has a communication interface and a control output terminal. Its communication interface is connected to the communication interface of the inverter 5 for data acquisition; its control output terminal is connected to the remote control terminal of the line-controlled DC circuit breaker 4 for sending commands.

[0035] When the system is running, the programmable controller 10 will determine whether there is a grounding short circuit fault in the DC cable of the photovoltaic string 1 based on the real-time operating data (such as insulation resistance, voltage, current, etc.) obtained from the inverter 5 and through the internal preset logic algorithm.

[0036] Once a fault is detected, the programmable logic controller 10 immediately outputs a disconnect command to the line-controlled DC circuit breaker 4 through its control output terminal, driving it to trip automatically. This automated process replaces the traditional dangerous manual live-line operation, fundamentally eliminating the risk of DC arc burns and high-voltage electric shock that maintenance personnel may face when handling faults. At the same time, by quickly cutting off the fault source, it effectively prevents the fault from escalating (such as cable overheating and fire), greatly improving the safety and reliability of the system.

[0037] As a preferred implementation, the line-controlled DC circuit breaker 4 is a bipolar circuit breaker, with its two poles connected in series in the positive and negative circuits of the photovoltaic string 1, respectively. Specifically, the positive pole cable 2 of the photovoltaic string 1 is connected to one input pole of the bipolar circuit breaker, and its corresponding output pole is then connected to the positive PV pole 6 of the inverter 5. Simultaneously, the negative pole cable 3 of the photovoltaic string is connected to the other input pole of the circuit breaker, and its output pole is connected to the negative PV pole 7 of the inverter 5. When the programmable controller 10 issues a disconnect command, the bipolar circuit breaker can simultaneously disconnect both the positive and negative DC circuits, achieving complete physical isolation of the faulty string. This bipolar disconnection method is safer and more thorough than unipolar disconnection, ensuring that the faulty circuit does not carry any floating potential, providing the highest level of safety assurance for subsequent maintenance work.

[0038] To achieve timely on-site alarms, this device also includes an audible and visual alarm 22, and the programmable logic controller (PLC) 10 is also equipped with an alarm output terminal, which is electrically connected to the audible and visual alarm 22. In this embodiment, the alarm output terminal of the PLC 10 is composed of the PLC output Y2 terminal 23 and the PLC output common terminal 13, forming an independent switch output channel. The power supply circuit of the audible and visual alarm 22 is connected in series in this channel. When the program logic of the PLC 10 determines a ground short circuit fault, it drives the Y1 terminal 16 to control the circuit breaker 4 to trip, and simultaneously drives the Y2 terminal 23 to close, thereby connecting the power supply to the audible and visual alarm 22. The audible and visual alarm 22 then emits a high-decibel buzzing sound and a conspicuous flashing light, which can immediately attract the attention of on-site maintenance personnel, prompting them to check the fault information and handle it in a timely manner, thereby greatly shortening the time from the occurrence of the fault to manual intervention and improving the maintenance response speed.

[0039] To facilitate on-site personnel monitoring of system status and setting parameters, this device also includes a touchscreen 20, which communicates with the programmable controller 10. The touchscreen 20 serves as a local human-machine interface (HMI), displaying in real-time, graphically the inverter's operating status and key parameters of each string obtained from the programmable controller 10. When a fault occurs, the touchscreen 20's interface automatically redirects to an alarm screen, clearly indicating the faulty string number and fault type. Maintenance personnel can intuitively understand the overall system operation and accurately locate fault points on-site without needing to carry laptops or other specialized tools. This significantly improves the efficiency and accuracy of fault diagnosis compared to the traditional method of using multimeters for piecemeal troubleshooting.

[0040] In a networked embodiment, to build a more flexible and scalable communication architecture, the device also includes a switch 18. Both the programmable logic controller (PLC) 10 and the touchscreen 20 are equipped with Ethernet interfaces, which are connected to the switch 18 via a first network cable 17 and a second network cable 19, respectively. This Ethernet-based connection not only ensures high-speed and stable data exchange between the PLC and the touchscreen but also facilitates subsequent system expansion, such as allowing easy access to more intelligent devices or monitoring terminals.

[0041] To achieve centralized monitoring of the entire photovoltaic power station, the switch 18 is also equipped with an external communication interface for connecting remote monitoring terminals. This interface can be connected to the power station's host computer monitoring system or cloud platform via another third network cable 21. Thus, when a ground fault occurs on-site, the fault information and alarm signals are not only displayed and sounded locally, but also uploaded to the remote monitoring center in real time via the switch 18. Management personnel can monitor the operating status of each string-level protection device within the power station without leaving their offices, achieving real-time synchronous display of on-site and remote operating data. This facilitates timely detection and handling of potential faults by maintenance personnel, thereby improving overall power generation efficiency and management level.

[0042] Regarding the specific implementation of data acquisition, the communication interface of the programmable controller 10 is preferably an RS485 communication interface, which is used to connect to the inverter 5. In actual wiring, shielded twisted-pair cable is used to connect the programmable controller's RS485 communication A+ terminal 11 to the inverter's RS485 communication A+ terminal 8, and the programmable controller's RS485 communication B- terminal 12 to the inverter's RS485 communication B- terminal 9. The RS485 communication protocol is chosen because of its excellent anti-interference performance and long transmission distance, making it very suitable for industrial sites with complex electromagnetic environments such as photovoltaic power stations. This ensures that the data acquired by the programmable controller 10 from the inverter 5 is authentic and reliable, providing a solid foundation for accurate fault diagnosis.

[0043] In terms of physical installation layout, this device also includes a first control box for accommodating the line-controlled DC circuit breaker 4. This first control box typically has a high IP protection rating and is installed near the combiner point of the photovoltaic string 1, that is, between the DC output terminal and the DC trunk cable to the inverter 5. Its main function is to provide near-end protection for this faulty DC trunk cable and ensure that the fault current is interrupted in the shortest possible time.

[0044] The device also includes a second control box for housing the programmable logic controller (PLC) 10. This second control box houses the PLC 10, the switch 18, and the power circuit breakers for the AC 220V neutral wire 14 and AC 220V live wire 15, which provide power to them. The touchscreen 20 is typically mounted on the control box door, while the audible and visual alarm 22 is mounted in a prominent position on the outside of the box. This second control box is installed near the inverter 5 housing, or on a wall, bracket, or other supporting structure adjacent to the inverter 5. This layout greatly facilitates the communication cable connection between the PLC and the inverter, and also allows maintenance personnel to check the operating status of this protection device simultaneously during inverter inspections, conforming to on-site operating habits.

[0045] Another embodiment of this utility model provides a photovoltaic power generation system. In addition to the conventional photovoltaic string 1 and inverter 5, this system also fully integrates the automatic disconnection control and alarm device for DC cable grounding short circuits described in the above embodiments. By integrating this device, the entire photovoltaic power generation system possesses proactive and intelligent DC-side safety protection capabilities from the initial design stage. This systematically solves the pain points of high safety risks, difficult fault diagnosis, and escalating losses in the background technology, comprehensively improving the automated operation and maintenance level and asset security of photovoltaic power plants.

[0046] The terms “first”, “second”, etc., are used to distinguish similar objects, not to describe or indicate a specific order or sequence.

[0047] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent in such process, method, article, or apparatus / device.

[0048] The technical solution of this utility model has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the protection scope of this utility model is obviously not limited to these specific embodiments. Without departing from the principle of this utility model, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of this utility model.

Claims

1. A control and alarm device for automatic disconnection of grounding short circuit in a photovoltaic system DC cable, characterized in that, include: Line-controlled DC circuit breaker (4) is installed on the DC circuit between the photovoltaic string (1) and the inverter (5); and The programmable logic controller (10) includes a communication interface connected to the communication interface of the inverter (5) and a control output terminal connected to the control terminal of the line-controlled DC circuit breaker (4). The programmable controller (10) is configured to: determine whether there is a ground short circuit fault based on the operating data obtained from the inverter (5), and when it is determined that there is a ground short circuit fault, output a disconnect command to the line-controlled DC circuit breaker (4) via the control output terminal.

2. The apparatus according to claim 1, characterized in that, The line-controlled DC circuit breaker (4) is a bipolar circuit breaker, with its two poles connected in series in the positive and negative circuits of the photovoltaic string (1).

3. The apparatus according to claim 1, characterized in that, It also includes an audible and visual alarm (22); the programmable controller (10) is also provided with an alarm output terminal, which is electrically connected to the audible and visual alarm (22).

4. The apparatus according to claim 1, characterized in that, It also includes a touch screen (20); the touch screen (20) is communicatively connected to the programmable controller (10).

5. The apparatus according to claim 4, characterized in that, It also includes a switch (18); both the programmable controller (10) and the touch screen (20) are provided with Ethernet interfaces and are connected to the switch (18) via the Ethernet interfaces.

6. The apparatus according to claim 5, characterized in that, The switch (18) is also provided with an external communication interface for connecting remote monitoring terminals.

7. The apparatus according to claim 1, characterized in that, The communication interface of the programmable controller (10) is an RS485 communication interface, and it is connected to the inverter (5) through the RS485 communication interface.

8. The apparatus according to claim 1, characterized in that, It also includes a first control box for accommodating the line-controlled DC circuit breaker (4); the first control box is located between the DC output terminal of the photovoltaic string (1) and the DC trunk cable to the inverter (5) for providing short-circuit protection for the DC trunk cable.

9. The apparatus according to claim 1, characterized in that, It also includes a second control box for housing the programmable controller (10); the second control box is mounted on the housing of the inverter (5) or on a support structure adjacent to the inverter (5).

10. A photovoltaic power generation system, characterized in that, include: Photovoltaic string (1); Inverter (5); and The photovoltaic system DC cable grounding short circuit automatic disconnection control alarm device as described in any one of claims 1 to 9.

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