Photovoltaic inverter protection device and application thereof
The photovoltaic inverter protection device uses current transformers and logic operations to determine photovoltaic string faults and drives circuit breakers to isolate abnormal strings, thus solving the problem of inverter damage caused by photovoltaic string faults and improving the safety and reliability of the system.
Patent Information
- Application Number
- CN202410543379.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-05
- Publication Date
- 2025-11-07
AI Technical Summary
In existing photovoltaic inverter connection methods, abnormal current input caused by photovoltaic string faults can easily lead to inverter shutdown or damage. In particular, the risk of fire is high in distributed photovoltaic systems, and there is a lack of effective fault diagnosis and handling methods.
A photovoltaic inverter protection device is adopted. The current value is obtained through positive and negative current transformers. The fault of the photovoltaic string is judged by logic operation, and the DC circuit breaker is driven to isolate the faulty string, ensuring that the normal string is input to the inverter and displaying the fault information.
It enables accurate identification and automatic isolation of photovoltaic string faults, protects the inverter's normal operation, reduces fire risk, and improves the system's safety, reliability, and stability.
Smart Images
Figure FT_1
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of photovoltaic protection devices, and proposes a photovoltaic inverter protection device application. BACKGROUND
[0002] Photovoltaic strings and photovoltaic inverters are two important components of photovoltaic power generation systems.
[0003] A photovoltaic string is a circuit composed of multiple photovoltaic modules (also known as solar panels) connected in series and / or parallel.
[0004] In a photovoltaic system, photovoltaic modules convert sunlight into direct current. By connecting multiple modules in series or parallel, the voltage and current can be adjusted to meet application requirements. The design and optimization of photovoltaic strings are crucial for improving the efficiency and reliability of the entire photovoltaic system.
[0005] A photovoltaic inverter, on the other hand, is a device that converts the direct current generated by photovoltaic strings into alternating current. Most industrial electrical equipment requires alternating current.
[0006] The working principle of an inverter is to convert direct current into alternating current through electronic components such as transistors, while ensuring that the output voltage and frequency match the requirements of the power grid. The performance of a photovoltaic inverter directly affects the overall efficiency and power quality of a photovoltaic system.
[0007] In short, photovoltaic strings are responsible for converting sunlight into direct current, while photovoltaic inverters are responsible for converting direct current into alternating current for daily use. Both work together to form a complete photovoltaic power generation system.
[0008] The existing connection methods of photovoltaic inverters and photovoltaic strings include series connection, parallel connection, and hybrid connection: Series connection is to connect multiple photovoltaic panels together to form a circuit, and then connect this circuit with the photovoltaic inverter. This connection method can increase the voltage of the system, but it will not increase the current. It is suitable for situations where there is a voltage requirement but no current requirement. In series connection, the photovoltaic panels need to be connected using plugs or connectors to ensure good contact and prevent loosening or falling off. At the same time, the total voltage of the multiple photovoltaic panel strings should not exceed the rated voltage of the inverter, otherwise it will damage the inverter; Parallel connection is to connect the positive poles of multiple photovoltaic panels together and the negative poles together to form a parallel circuit, and then connect this circuit with the inverter. This connection method can increase the current of the system, but it will not increase the voltage. It is suitable for situations where there is a current requirement but no voltage requirement; Hybrid connection is to first connect multiple photovoltaic panels in series to form several sub-circuits, then connect these sub-circuits in parallel, and finally connect the circuit with the inverter. This way, both the voltage and current of the system can be increased.
[0009] It can be seen that the photovoltaic inverter is connected with multiple groups of photovoltaic strings, and is directly connected to the photovoltaic inverter, and the connection mode has the following disadvantages: When a certain photovoltaic string fails abnormally, the positive and negative electrode current and voltage of the photovoltaic string will change abnormally, and the abnormal change caused by the failure of the photovoltaic string is directly input into the photovoltaic inverter, which causes the abnormal current to be directly input into the photovoltaic inverter, and further causes the inverter to stop working or be damaged.
[0010] Especially in distributed photovoltaic, photovoltaic strings often cause serious accidents due to failure. Photovoltaic strings in distributed photovoltaic have many points and wide surfaces, photovoltaic cable wiring installation points are many and long, and operating environments are different, which are prone to fire accidents. In many cases, photovoltaic fires are caused by the lack of self-protection devices and inverter protection devices or the failure of protection control. Therefore, how to accurately judge and handle the failure of the photovoltaic string is a technical problem to be solved. SUMMARY
[0011] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a photovoltaic inverter protection device and its application. The normal photovoltaic string has equal positive and negative electrode charges, opposite polarity, and the sum of the positive and negative electrode voltages is equal to zero. When a photovoltaic string fails abnormally, the positive and negative electrode current and voltage of the photovoltaic string will deviate from the two protection criteria. The photovoltaic inverter protection device determines the failure of the photovoltaic string according to the deviation. The device drives the DC circuit breaker of the abnormal photovoltaic string to act and isolate, ensures the normal operation of the normal photovoltaic string input into the photovoltaic inverter, and at the same time, sends the abnormal information of the abnormal photovoltaic string.
[0012] In order to achieve the above purpose, the present application adopts the following technical scheme: a photovoltaic inverter protection device, comprising a control module and a power module, the input side of the control module is connected with a positive current transformer and a negative current transformer, and the output side of the control module is connected with a DC circuit breaker; the positive current transformer and the negative current transformer are respectively used for acquiring the positive electrode current value and the negative electrode current value of the positive electrode photovoltaic cable and the negative electrode photovoltaic cable and transmitting to the control module; the control module is used for logical operation according to the positive electrode current value and the negative electrode current value, and outputs an execution signal according to the operation result to control the on-off of the DC circuit breaker; the power module is connected with the control module, the positive current transformer and the negative current transformer respectively, and is used for power supply.
[0013] Further, the control module is also connected with a display module for displaying the abnormal information.
[0014] Further, the control module, the power module, the DC circuit breaker, the positive current transformer and the negative current transformer are arranged in the box. The box is provided with two pairs of connectors, one pair of which is an input connector for connecting the photovoltaic string, and the other pair is an output connector for connecting the photovoltaic inverter.
[0015] Further, the two pairs of connectors are connected through photovoltaic cables, and the DC circuit breaker is provided with two groups of normally closed contacts, which are respectively connected in series on the photovoltaic cables between the two pairs of connectors.
[0016] Further, the positive current transformer and the negative current transformer are respectively arranged on the photovoltaic cables between the two pairs of connectors.
[0017] Further, the DC circuit breaker is further provided with a tripper for disconnecting the moving contact according to an execution signal.
[0018] Further, the connector is an MC4 connector.
[0019] Further, the logic operation rule of the control module is that the positive current value and the negative current value are the same, and the sum is equal to zero, then the photovoltaic string works normally, and the positive current value and the negative current value are not the same or the sum is not equal to zero, then the photovoltaic string is faulty.
[0020] Further, the positive current transformer, the negative current transformer, the DC circuit breaker and the connector are multiple groups, and the control module is provided with multiple input terminals and output terminals.
[0021] Further, the photovoltaic inverter and multiple photovoltaic strings are included, and the multiple photovoltaic strings are connected with the photovoltaic inverter through the photovoltaic inverter protection device.
[0022] The photovoltaic string fault can be automatically isolated, the controller of the photovoltaic inverter protection device box is used to realize the logic operation of the positive current and the negative current of the photovoltaic string and the logic operation of the positive voltage and the negative voltage of the photovoltaic string, the disconnection of the photovoltaic string is judged, the output instruction is given to the tripper of the DC circuit breaker, the tripper is driven to act, the negative moving contact and the positive moving contact are driven to act, the DC circuit breaker is tripped, the photovoltaic inverter is protected from the influence of the photovoltaic string fault, the normal photovoltaic string is ensured to be connected to the photovoltaic inverter, the normal operation information and the fault information of all photovoltaic strings connected to the photovoltaic inverter are output and displayed on the liquid crystal display screen, and the fault information of the fault photovoltaic string is output. BRIEF DESCRIPTION OF DRAWINGS
[0024] Figure 1 is a structural diagram of the present application; In the figure: 1, DC circuit breaker, 2, tripping device, 3, photovoltaic string, 4, photovoltaic inverter, 5, photovoltaic inverter protection device box, 6, power module, 7, liquid crystal display, 8, controller, 9, positive MC4 connector, 10, positive photovoltaic cable, 11, negative photovoltaic cable, 12, negative MC4 connector, 13, negative moving contact, 14, positive moving contact, 15, positive current transformer, 16, negative current transformer. DETAILED DESCRIPTION
[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments.
[0027] Embodiment 1
[0028] As Figure 1 A photovoltaic inverter protection device mainly consists of a control module, a current transformer, a DC circuit breaker (1), a display screen and a power module (6). The current transformer includes a positive current transformer (15) and a negative current transformer (16). The DC circuit breaker (1) is provided with two moving contacts and a tripping device (2). The power module (6) is connected with each module and the current transformer respectively for power supply.
[0029] The control module is provided with a plurality of input terminals and output terminals as well as a power terminal, and a logic operation unit is built-in. The input terminals are used to connect the current transformer to obtain the current value. The logic operation unit performs logic operation according to the current value, and outputs an execution signal according to the logic operation result. The output terminals are used to connect the tripping device (2), the display screen and other execution or display modules. The power terminal is used to connect the power module (6).
[0030] The current transformer includes a positive current transformer (15) and a negative current transformer (16). The positive current transformer (15) and the negative current transformer (16) are respectively installed on the positive photovoltaic cable (10) and the negative photovoltaic cable (11) for detecting the current value in the photovoltaic cable and transmitting the detected current value to the control module.
[0031] The two moving contacts of the DC circuit breaker (1) are respectively connected in series with the positive photovoltaic cable (10) and the negative photovoltaic cable (11). The tripping device (2) is communicatively connected with the output terminal of the control module.
[0032] The display module is a liquid crystal display screen (7) connected with the output terminal of the control module for displaying the positive current value, the negative current value and the logic operation result.
[0033] The logic operation rule of the logic operation unit is: If the positive and negative current values are the same and their sum is equal to zero, the photovoltaic string (3) is working normally. If the positive and negative current values are not the same or their sum is not equal to zero, the photovoltaic string (3) is faulty.
[0034] Embodiment 2
[0035] As Figure 1 The photovoltaic inverter protection device further comprises a box body, the control module, the power module (6), the DC circuit breaker (1), the positive current transformer (15) and the negative current transformer (16) are all arranged inside the box body.
[0036] The box body is provided with two pairs of connectors, one pair of which is an input connector for connecting the photovoltaic string (3), and the other pair is an output connector for connecting the photovoltaic inverter, and the connectors are all MC4 connectors.
[0037] The two pairs of connectors are connected through photovoltaic cables, and the DC circuit breaker (1) is provided with two groups of normally closed contacts, which are respectively connected in series on the photovoltaic cables between the two pairs of connectors.
[0038] The positive current transformer (15) and the negative current transformer (16) are respectively arranged on the photovoltaic cables between the two pairs of connectors.
[0039] The positive current transformer (15), the negative current transformer (16), the DC circuit breaker (1) and the connector are multiple groups, the control module is provided with multiple groups of input terminals and output terminals, and the photovoltaic inverter protection device is connected with the photovoltaic inverter through the photovoltaic inverter and multiple groups of photovoltaic strings (3).
[0040] Embodiment 3
[0041] The photovoltaic inverter protection device comprises a current comparator for comparing the size and polarity of the positive and negative current values.
[0042] The current comparator is connected with the control module, receives the current values detected by the positive current transformer (15) and the negative current transformer (16), and compares them. If the positive and negative current values are equal in size and opposite in polarity (i.e. their sum is equal to zero), the current comparator will send a signal to the control module indicating that the photovoltaic string (3) is working normally. If the positive and negative current values are not equal in size or the same in polarity (i.e. their sum is not equal to zero), the current comparator will send a different signal to the control module indicating that the photovoltaic string (3) is faulty.
[0043] After receiving the signal of the current comparator, the control module will make a judgment according to the preset logic operation rule and output the corresponding execution signal. If it is judged that the photovoltaic string (3) is faulty, the control module will send an execution signal to the trip unit (2) of the DC circuit breaker (1), so that the trip unit (2) drives the action to open the moving contact of the DC circuit breaker (1), thereby isolating the faulty photovoltaic string (3) and protecting the photovoltaic inverter from being affected.
[0044] A communication module can also be provided to transmit the judgment result and fault information of the control module to the remote monitoring center, facilitating remote monitoring and maintenance by the operation and maintenance personnel.
[0045] In summary, the photovoltaic inverter protection device in Example Three improves the detection accuracy and response speed of the photovoltaic string (3) fault by introducing the current comparator, further ensuring the stable operation of the photovoltaic inverter and the safety and reliability of the photovoltaic system.
[0046] Example 4
[0047] As Figure 1The application method of a photovoltaic inverter protection device includes the following steps: connecting the positive photovoltaic cable (10) of all photovoltaic strings (3) connected to the photovoltaic inverter to the positive moving contact (14) terminal of the DC circuit breaker (1) through the positive MC4 joint of the photovoltaic inverter protection device box (5) according to the photovoltaic inverter category; then connecting the positive terminal of the DC circuit breaker (1) to the photovoltaic inverter through the positive current transformer (15) and the positive MC4 joint of the photovoltaic inverter protection device box (5); connecting the negative photovoltaic cable (11) of all photovoltaic strings (3) connected to the photovoltaic inverter to the negative moving contact (13) terminal of the DC circuit breaker (1) through the negative MC4 joint of the photovoltaic inverter protection device box (5); then connecting the negative terminal of the DC circuit breaker (1) to the photovoltaic inverter through the negative current transformer (16) and the negative MC4 joint of the photovoltaic inverter protection device box (5); connecting the power supply from the photovoltaic inverter to the power module (6) of the photovoltaic inverter protection device box (5), and connecting the output of the voltage conversion of the power module (6) to the liquid crystal display screen (7), the logic controller (8), the positive current transformer (15) and the negative current transformer (16) respectively and providing power supply for them; collecting the positive current output of the photovoltaic string (3) through the positive current transformer (15) of the photovoltaic inverter protection device box (5) and connecting the output to the logic controller (8), and collecting the negative current output of the photovoltaic string (3) through the negative current transformer (16) of the photovoltaic inverter protection device box (5) and connecting the output to the logic controller (8), and performing size and direction logical operation on the positive and negative currents of the photovoltaic string (3) by the logic controller (8); collecting the positive voltage output of the photovoltaic string (3) from the positive terminal of the DC circuit breaker (1) of the photovoltaic inverter protection device box (5) and connecting the output to the logic controller (8), and collecting the negative voltage output of the photovoltaic string (3) from the negative terminal of the DC circuit breaker (1) of the photovoltaic inverter protection device box (5) and connecting the output to the logic controller (8), and performing size and direction logical operation on the positive and negative voltages of the photovoltaic string (3) by the logic controller (8); when the photovoltaic string (3) appears fault and abnormality, the logic controller (8) of the photovoltaic inverter protection device box (5) obtains the size abnormality inequality and direction abnormality logical operation result of the positive and negative currents of the photovoltaic string (3) and the size abnormality inequality and direction abnormality logical operation result of the positive and negative voltages of the photovoltaic string (3), the logic controller (8) obtains the logical judgment result of disconnecting the photovoltaic string (3) according to the logical operation, the logic controller (8) outputs the instruction to the release (2) of the DC circuit breaker (1) of the photovoltaic string (3), the release (2) obtains the instruction and drives the action, the release (2) drives the connection of the negative moving contact (13) and the positive moving contact (14) to realize the tripping of the DC circuit breaker (1), and the photovoltaic string (3) with fault and abnormality is automatically isolated.The logic controller (8) of the photovoltaic inverter protection device box (5) outputs and displays the normal operation information and fault information of all photovoltaic strings (3) connected to the photovoltaic inverter on the liquid crystal display screen (7). At the same time, the fault abnormal information of the fault abnormal photovoltaic string (3) is sent out.
[0048] The above merely describes the preferred embodiments of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can make equivalent replacements or changes according to the technical solution and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.
Claims
1. A photovoltaic inverter protection device comprising a control module and a power module, characterized in that, The input side of the control module is connected with a positive current transformer and a negative current transformer, and the output side of the control module is connected with a DC circuit breaker; the positive current transformer and the negative current transformer are respectively used for acquiring positive current values and negative current values of positive and negative photovoltaic cables and transmitting to the control module; the control module is used for logical operation according to the positive current values and the negative current values, and outputs an execution signal according to the operation result to control the on-off of the DC circuit breaker; the power module is connected with the control module, the positive current transformer and the negative current transformer respectively, and is used for power supply.
2. A photovoltaic inverter protection device according to claim 1, characterized in that The control module is also connected with a display module for displaying fault abnormal information.
3. A photovoltaic inverter protection device according to claim 1 or 2, characterized in that It also includes a box body, the control module, the power module, the DC circuit breaker, the positive current transformer and the negative current transformer are all installed in the box body; the box body is provided with two connectors, one of which is an input connector for connecting photovoltaic strings, and the other is an output connector for connecting a photovoltaic inverter.
4. A photovoltaic inverter protection device according to claim 3, characterized in that The two connectors are connected by photovoltaic cables, and the DC circuit breaker is provided with two groups of normally closed contacts, which are respectively connected in series on the photovoltaic cables between the two connectors.
5. A photovoltaic inverter protection device according to claim 3, characterized in that, The positive current transformer and the negative current transformer are respectively installed on the photovoltaic cables between the two connectors.
6. A photovoltaic inverter protection device according to claim 5, characterized in that The DC circuit breaker is also provided with a tripper for disconnecting the moving contact according to the execution signal.
7. A photovoltaic inverter protection device according to any of claims 4-6, characterized in that, The connector is an MC4 connector.
8. A photovoltaic inverter protection device according to claim 7, characterized in that The logical operation rule of the control module is that the positive current value and the negative current value are the same, and the sum is equal to zero, then the photovoltaic string works normally; the positive current value and the negative current value are not the same or the sum is not equal to zero, then the photovoltaic string is faulty.
9. A photovoltaic inverter protection device according to claim 8, characterized in that The positive current transformer, the negative current transformer, the DC circuit breaker and the connector are multiple groups, and the control module is provided with multiple input terminals and output terminals.
10. Use of a photovoltaic inverter protection device according to claim 9, characterized in that, It includes a photovoltaic inverter and multiple photovoltaic strings, and the multiple photovoltaic strings are connected with the photovoltaic inverter through the photovoltaic inverter protection device.