Photovoltaic combiner box with ground fault protection function

Abstract

This utility model belongs to the field of photovoltaic module application technology, and relates to a photovoltaic combiner box with ground fault protection function. It includes a box body, within which are respectively arranged a positive combiner bus, a negative combiner bus, a positive main bus, a negative main bus, multiple positive branch lines and negative branch lines. It also includes a control unit and an alarm indicator light. A calculation module is installed in the control unit, and the alarm indicator light is connected to the control unit. A first current Hall sensor and a smart circuit breaker are respectively installed on each positive branch line, and each first current Hall sensor and smart circuit breaker is connected to the control unit. A second current Hall sensor is respectively installed on each negative branch line, and each second current Hall sensor is connected to the control unit. This utility model uses current Hall sensors to synchronously sample the positive and negative currents of each photovoltaic module to be monitored, and determines the insulation resistance by calculating the leakage current, thereby determining the effectiveness of the ground fault protection.

Description

Technical Field

[0001] This utility model belongs to the field of photovoltaic module application technology, and specifically relates to a photovoltaic combiner box with ground fault protection function. Background Technology

[0002] Photovoltaic systems operate in harsh outdoor environments (high temperature, high humidity, salt spray, etc.) for extended periods, making the cable insulation layer prone to aging and damage, leading to decreased insulation performance and subsequent ground leakage. This leakage not only results in a loss of power generation but, more seriously, can cause electric shock accidents when people come into contact with it, posing a significant safety hazard.

[0003] In existing photovoltaic power plant systems, the insulation resistance of the entire photovoltaic module circuit can only be detected at the inverter end, making it impossible to pinpoint the location of each individual photovoltaic module. Therefore, there is an urgent need for a new type of combiner box that can perform real-time and accurate monitoring of the input circuit of each photovoltaic module in the combiner box, and can provide graded alarms and rapid disconnection before insulation faults develop to a dangerous level, in order to ensure system safety and the safety of personnel and property. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide a photovoltaic combiner box with ground fault protection function based on current difference detection, which can monitor the insulation status of each photovoltaic module in real time and has ground fault protection function, thereby effectively preventing electric shock accidents and facilitating operation and maintenance.

[0005] This utility model is implemented as follows: a photovoltaic combiner box with ground fault protection function is provided, including a box body. Inside the box body are a positive busbar, a negative busbar, a positive main line, a negative main line, multiple positive branch lines, and multiple negative branch lines. The positive main line is connected to the positive busbar, and the negative main line is connected to the negative busbar. Each positive branch line is connected to the positive busbar, and each negative branch line is connected to the negative busbar. Each set of positive and negative branch lines is electrically connected to the busbar of its corresponding photovoltaic module to be monitored. A control unit and an alarm indicator light are also provided inside the box body. The alarm indicator light is connected to the control unit. A calculation module is provided within the control unit. A first current Hall sensor and a smart circuit breaker are provided on each positive branch line, and each first current Hall sensor and smart circuit breaker is connected to the control unit. A second current Hall sensor is provided on each negative branch line, and each second current Hall sensor is connected to the control unit.

[0006] Furthermore, a main circuit breaker and a voltage Hall sensor are also installed inside the enclosure. The main circuit breaker is installed on the positive bus and the negative bus, and the voltage Hall sensor is installed on the positive bus.

[0007] Compared with existing technologies, this utility model provides a photovoltaic combiner box with ground fault protection function. The box includes a housing containing a positive busbar, a negative busbar, a positive main line, a negative main line, multiple positive and negative branch lines, a control unit, and alarm indicator lights. The control unit contains a calculation module, and the alarm indicator lights are connected to the control unit. Each positive branch line is equipped with a first current Hall sensor and a smart circuit breaker, each connected to the control unit. Each negative branch line is equipped with a second current Hall sensor, each connected to the control unit. This utility model uses current Hall sensors to synchronously sample the positive and negative currents of each monitored photovoltaic module and calculates the leakage current to determine the insulation resistance, thereby determining the effectiveness of the ground fault protection. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of a preferred embodiment of the photovoltaic combiner box with ground fault protection function of this utility model.

[0009] The labels in the diagram are as follows: 1. Enclosure; 2. Positive busbar; 3. Negative busbar; 4. Positive main bus; 5. Negative main bus; 6. Positive branch line; 7. Negative branch line; 8. Control unit; 9. Alarm indicator light; 10. First current Hall sensor; 11. Intelligent circuit breaker; 12. Second current Hall sensor; 13. Main circuit breaker; 14. Voltage Hall sensor. Detailed Implementation

[0010] To make the technical problems, technical solutions, and beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0011] Please refer to Figure 1 As shown, a preferred embodiment of the photovoltaic combiner box with ground fault protection function of this utility model includes a box body 1, and a positive combiner bus 2, a negative combiner bus 3, a positive bus 4, a negative bus 5, a plurality of positive branches 6 and negative branches 7 are respectively arranged in the box body 1.

[0012] Positive bus 4 is connected to positive busbar 2, and negative bus 5 is connected to negative busbar 3. Each positive branch 6 is connected to positive busbar 2, and each negative branch 7 is connected to negative busbar 3. Each set of positive branch 6 and negative branch 7 is electrically connected to the corresponding busbar (not shown in the figure) of the photovoltaic module to be monitored.

[0013] Inside the housing 1, a control unit 8 and an alarm indicator light 9 are also installed, with the alarm indicator light 9 connected to the control unit 8. A calculation module is installed inside the control unit 8. A first current Hall sensor 10 and a smart circuit breaker 11 are respectively installed on each positive branch 6, and each first current Hall sensor 10 and smart circuit breaker 11 is connected to the control unit 8. A second current Hall sensor 12 is respectively installed on each negative branch 7, and each second current Hall sensor 12 is connected to the control unit 8.

[0014] The enclosure 1 is also equipped with a main circuit breaker 13 and a voltage Hall sensor 14. The main circuit breaker 13 is installed on the positive bus 4 and the negative bus 5, and the voltage Hall sensor 14 is installed on the positive bus 4.

[0015] The calculation module first calculates the difference between the first current Hall sensor 10 and the second current Hall sensor 12 in each group as the leakage current I. leak Then, according to the formula R=U / I leak The insulation resistance R was calculated, and the voltage Hall sensor 14 detected the total voltage U of the positive bus 4 of the photovoltaic module.

[0016] The grounding protection capability of a photovoltaic module is determined by the value of its insulation resistance R. The larger the insulation resistance R, the better the grounding protection capability of the photovoltaic module.

[0017] When the insulation resistance R is not greater than 40MΩ, the grounding protection capability is lower than the danger value, and there is a risk of leakage. The alarm indicator light turns red, and the control unit 8 sends a disconnection command to the smart circuit breaker 11 where the photovoltaic module is located, and notifies the maintenance personnel to carry out inspection and maintenance.

[0018] When the insulation resistance R is greater than 40MΩ and less than 100MΩ, the grounding protection capability is low, and the alarm indicator light will turn yellow to alert maintenance personnel.

[0019] This utility model of a photovoltaic combiner box with ground fault protection function has the following features: 1. Real-time monitoring: Hall effect sensors are used to synchronously sample the positive and negative currents of each photovoltaic module, which can calculate minute leakage currents in real time, with a sensitivity far exceeding that of traditional solutions. 2. Proactive safety protection: By calculating the insulation resistance, an early warning (yellow light) can be issued before the insulation level drops to a dangerous value, reminding maintenance personnel to intervene in advance, changing "passive protection" to "proactive protection"; 3. Rapid disconnection and selective protection: Once a dangerous leakage is detected, the branch of the faulty photovoltaic module can be disconnected individually in a very short time (milliseconds) instead of the entire power supply, which ensures the absolute safety of personnel and minimizes power generation loss. 4. Convenient fault location: Alarm information can be accurately located down to the branch of a specific photovoltaic module, and can distinguish between warning and fault status, which greatly facilitates the fault diagnosis and repair work of operation and maintenance personnel and improves operation and maintenance efficiency; 5. Simple structure and easy to implement: Based on the existing combiner box structure, it can be implemented by adding Hall sensors and upgrading the control logic. The cost increase is limited, but the safety performance and intelligence level are significantly improved.

[0020] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A photovoltaic combiner box with ground fault protection function, comprising a box body, wherein a positive busbar, a negative busbar, a positive main bus, a negative main bus, multiple positive branch lines and negative branch lines are respectively arranged inside the box body, the positive main bus is connected to the positive busbar, the negative main bus is connected to the negative busbar, each positive branch line is connected to the positive busbar, each negative branch line is connected to the negative busbar, and each set of positive and negative branch lines is electrically connected to the busbar of the corresponding photovoltaic module to be monitored, characterized in that, The enclosure also includes a control unit and an alarm indicator light, which are connected to the control unit. A calculation module is installed inside the control unit. A first current Hall sensor and a smart circuit breaker are installed on each positive branch line, and each first current Hall sensor and smart circuit breaker is connected to the control unit. A second current Hall sensor is installed on each negative branch line, and each second current Hall sensor is connected to the control unit.

2. The photovoltaic combiner box with ground fault protection function as described in claim 1, characterized in that, The enclosure also houses a main circuit breaker and a voltage Hall sensor. The main circuit breaker is located on the positive and negative bus terminals, while the voltage Hall sensor is located on the positive bus terminal.

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