Impedance cabinet specially used for photovoltaic direct current arc fault protection electric appliance detection equipment

Abstract

The utility model discloses an impedance cabinet specially used for photovoltaic direct-current arc fault protection electric appliance detection equipment, which comprises a cabinet body frame and side cross beams arranged on the side surfaces of the cabinet body frame, and the cabinet body frame and the side cross beams are respectively provided with mounting holes arranged according to modulus. The side cross beams are arranged on the cabinet body frame through the mounting holes; the side cross beams are provided with fixed vertical plates located in the cabinet body frame, the front side of the cabinet body frame is provided with a front sealing plate, and the front sealing plate is provided with a plurality of rectangular openings used for accommodating modularized impedance network modules and / or line inductance modules. And one end, far away from the front sealing plate, of the modularized impedance network module and / or the line inductance module is fixed on the fixed vertical plate. The photovoltaic impedance cabinet simulates line impedance in an actual line after the power supply cabinet outputs voltage-stabilizing and constant-current direct current, and provides approximately constant high-voltage impedance for a system so as to ensure comparability of different measurement results.

Description

Technical Field

[0001] The utility model relates to the technical field of photovoltaic power generation detection, in particular to an impedance cabinet specially used for photovoltaic DC arc fault protection electrical appliance detection equipment. Background Art

[0002] With the increasing shortage of renewable energy around the world, my country has also paid more attention to the development and utilization of renewable energy. There are many types of renewable energy, and solar energy has attracted the attention of various countries due to its advantages of low pollution, safety, and abundant resources. Among them, photovoltaic power generation is the main way to develop and utilize solar energy. Photovoltaic power generation is a technology that uses the photovoltaic effect of semiconductor interfaces to directly convert light energy into electrical energy.

[0003] However, due to the rapid development of the photovoltaic industry in recent years and the aging of photovoltaic power stations, the frequency of faults in photovoltaic systems has become increasingly high. The DC output voltage of the photovoltaic system increases with the increase of photovoltaic strings, and can reach up to thousands of volts. In a DC system, the current does not have a zero crossing point, and an arc can be generated in the system when the DC voltage is greater than 11V or its current exceeds 1A. At the same time, the photovoltaic components continue to generate electricity after the fault occurs, which further maintains the burning of the arc. In a photovoltaic system, once a DC fault arc occurs, if effective protective measures are not taken in time, a high temperature of more than 3000℃ will be generated, which will cause a fire. In addition, compared with traditional systems, photovoltaic systems are more affected by light intensity, temperature, inverter noise, etc., making fault arcs in photovoltaic systems more difficult to detect.

[0004] In order to avoid the serious consequences of arc faults as much as possible, Underwriter-Laboratories-Inc developed the first version of UL 1699B standard in 2018 to evaluate the effectiveness of arc fault detection methods in photovoltaic DC systems. The National Electrical Code (NEC) 690.11 implemented in 2011 requires that DC arc fault detection devices and photovoltaic DC arc fault protection devices must be installed in photovoltaic systems with DC voltage greater than 80V. Photovoltaic DC arc fault protection devices are a type of protection device that disconnects the power circuit before the arc fault develops into a fire or a short circuit occurs in the circuit by identifying the characteristic signal of the arc fault in the circuit.

[0005] Based on the above situation, the reliability detection of photovoltaic DC arc fault protection devices is particularly important. However, there are very few detection devices for photovoltaic DC arc fault protection devices on the market, and they have single functions and can only perform single line structures. The degree of automation is low and the test accuracy is not high, which seriously affects the accuracy of the test and creates safety hazards.

[0006] Therefore, there is a need for a photovoltaic DC arc fault protection electrical appliance detection device to solve the problems of low automation and low test accuracy of arc fault detection in the prior art, and to provide testing and data support for photovoltaic DC arc fault protection electrical appliances. But in fact, the current generated by solar panels is complicated during the transmission process, and a large number of extra-long cables cannot be placed in the laboratory. Therefore, in the test system, if you want to truly simulate the situation of a photovoltaic power station, you must simulate the actual loss of electric energy during the transmission process, that is, you need to connect an impedance network product after the simulated power supply to simulate the actual extra-long line from the solar cell array to the junction box. Therefore, the design and principle of the photovoltaic impedance product is directly related to the detection accuracy of the entire detection equipment and the complexity of the circuit structure that can be detected. Utility Model Content

[0007] The technical problem to be solved by the utility model is to provide an impedance cabinet specially used for photovoltaic DC arc fault protection electrical detection equipment, which is used to simulate the impedance loss generated in various complex circuits, transmission circuits of different lengths, and circuits with different connection methods in photovoltaic power stations.

[0008] In order to solve the above technical problems, the technical solutions provided by the utility model are as follows:

[0009] An impedance cabinet specially used for photovoltaic DC arc fault protection electrical appliance detection equipment, comprising a cabinet frame and a side beam arranged on the side of the cabinet frame, the cabinet frame and the side beam are respectively provided with mounting holes arranged according to the module, and the side beam is arranged on the cabinet frame through the mounting holes;

[0010] The side crossbeam is provided with a fixed vertical plate located inside the cabinet frame, the front side of the cabinet frame is provided with a front cover plate, the front cover plate is provided with a plurality of openings for accommodating modular impedance network modules and / or line inductance modules, and one end of the modular impedance network module and / or line inductance module away from the front cover plate is fixed to the fixed vertical plate.

[0011] Furthermore, the impedance network module adopts a modular design, and the impedance network module is composed of inductors, capacitors, resistors of various specifications and a circuit board on which the capacitors are mounted, which is used to simulate the impedance of complex power grid circuits of different lengths.

[0012] Furthermore, the line inductance module adopts a modular design, and the line inductance module is composed of several air-core inductors of different models.

[0013] Furthermore, a handle is provided on the front of the impedance network module or the line inductance module.

[0014] Furthermore, the impedance network module or the line inductance module is fixed in the cabinet frame via a connecting piece, one end of the connecting piece is fixed to the impedance network module or the line inductance module, and the other end is connected to the fixed vertical plate.

[0015] Furthermore, movable casters are fixedly installed at the four corners of the bottom of the cabinet frame; a top plate is fixedly arranged on the top of the cabinet frame; and sealing plates are arranged on the left and right sides of the cabinet frame.

[0016] Furthermore, a rear door with a double-door structure is symmetrically arranged on the rear side of the cabinet frame, a shutter is arranged on the rear door, and the rear door is hinged to the cabinet frame.

[0017] Furthermore, the front sealing plate is in a box-shaped structure as a whole, and is installed in an embedded manner.

[0018] Furthermore, the side cross beam is in a C-shaped structure, and the three sides of the C-shaped structure are respectively provided with mounting holes arranged according to a preset pattern.

[0019] Furthermore, the fixed vertical plate is in an L-shaped structure, and mounting holes arranged according to a preset rule are respectively provided on two side surfaces of the L-shaped structure.

[0020] Compared with the prior art, the impedance cabinet specially used for photovoltaic DC arc fault protection electrical detection equipment of the utility model has the following beneficial effects:

[0021] In order to detect the reliability of photovoltaic DC arc fault protection appliances, the impedance cabinet uses modular impedance network modules and line inductance modules to simulate various complex circuits, circuits of different lengths, and circuits with different connection methods in photovoltaic power stations. After the power cabinet outputs the DC power supply according to the test requirements, it simulates the line impedance in the actual line, provides the system with approximately constant high-voltage impedance, and more realistically simulates the impact of the line on high-frequency signals to ensure the comparability of different measurement results. The setting of modular impedance network modules and line inductance modules makes it easier for the impedance cabinet to automatically switch on and off different circuits, simulating the impedance conditions of real photovoltaic power stations.

[0022] The entire cabinet frame of the impedance cabinet has mounting holes arranged according to the module. Therefore, bolt connection can be used for the installation connection of the overall frame and the installation connection of the side beams and fixed vertical plates. No welding is required. It has high installation flexibility and high versatility. When some components are eliminated, the GGD cabinet has good installation flexibility and will not cause installation problems due to the modification or update of components. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The overall structural diagram of the impedance cabinet provided by the embodiment of the utility model for use in photovoltaic DC arc fault protection electrical appliance detection equipment;

[0024] Figure 2 A schematic diagram of the front structure of an impedance cabinet specially used for photovoltaic DC arc fault protection electrical appliance detection equipment provided by an embodiment of the utility model;

[0025] Figure 3 A schematic diagram of the side structure of an impedance cabinet specially used for photovoltaic DC arc fault protection electrical appliance detection equipment provided by an embodiment of the utility model;

[0026] Figure 4 A schematic diagram of the structure of an impedance network module / line inductance module provided in an embodiment of the utility model;

[0027] Figure 5 A topological structure diagram of an impedance network module provided in an embodiment of the utility model;

[0028] Figure 6 A topological structure diagram of a line inductance module provided in an embodiment of the utility model;

[0029] Description of main reference numerals:

[0030] 1-cabinet frame; 101-top long beam; 102-top short beam; 103-column; 104-bottom long beam; 105-bottom short beam; 106-rear door; 107-movable casters; 108-top plate; 109-front cover plate; 2-side cross beams; 3-fixed vertical plate; 4-impedance network module; 5-line inductance module; 6-handle; 7-connecting piece. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0032] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0033] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, an integral connection, or a detachable connection; it can be the internal connection of two components; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] See also Figure 1-Figure 3 The embodiment of the utility model provides an impedance cabinet specially used for photovoltaic DC arc fault protection electrical detection equipment, and the impedance cabinet includes a cabinet frame 1, and the cabinet frame 1 is respectively provided with mounting holes arranged according to the module, that is, the mounting holes are arranged according to the predetermined size rule. The composition structure of the cabinet frame 1 includes a group of top long beams 101, top short beams 102, columns 103, bottom long beams 104 and bottom short beams 105. Among them, the top long beams 101, top short beams 102, columns 103, bottom long beams 103 and bottom short beams 105 are respectively provided with mounting holes arranged according to the module, which is used to improve the versatility of product assembly. Therefore, in the connection between the top long beams 101, top short beams 102, bottom long beams 104 and bottom short beams 105 and the columns 103, bolt connection can be adopted, without welding, stable installation, reliable structure and convenient maintenance.

[0035] The bottom of the cabinet frame 1 is fixedly provided with movable casters 107 at the four corners; the top of the cabinet frame 1 is fixedly provided with a top plate 108; the rear side of the cabinet frame 1 is symmetrically provided with a double-door structure rear door 106, and the rear door 106 is provided with a heat dissipating and waterproof shutter, and the rear door is connected to the cabinet frame 1 with a galvanized shaft hinge for installation, which is convenient for disassembly; the left and right sides of the cabinet frame 1 are sealing plates, and the entire cabinet frame panel adopts a spraying process, which has strong adhesion and good texture. The whole cabinet is matte in color, which avoids the dazzling effect and creates a more comfortable visual environment for the staff. The front of the cabinet frame 1 is provided with a front sealing plate 109, which is a box-shaped structure as a whole, and is formed by bending a 2.0 cold-rolled plate in an integrated manner, and the installation method is embedded installation. The front sealing plate 109 is provided with a number of rectangular openings for installing modular impedance network modules 4 or line inductance modules 5. In this embodiment, two openings are provided in each row of the front sealing plate 109, and a total of 7 rows are provided.

[0036] A side crossbeam 2 is arranged between two uprights 103 on the side of the cabinet frame 1. The side crossbeam 2 is a C-shaped structure, and the three sides of the C-shaped structure are provided with mounting holes arranged in a module of E=20mm, and the diameter of the mounting holes is 10mm, which strengthens the strength of the cabinet frame 1; and a fixed vertical plate 3 is installed on the side crossbeam 2. The fixed vertical plate 3 is an L-shaped structure as a whole, and mounting holes arranged in a module of E=20mm are arranged on two surfaces of the L-shaped structure, and the mounting holes are 10mm in diameter, which are used to fix the impedance network module 4 or the line inductance module 5.

[0037] The side crossbeam 2 is installed between two adjacent columns 103 on the upper side of the cabinet frame 1 through the installation hole. The mechanical structure of the photovoltaic impedance cabinet has good installation flexibility and high versatility. Even if the main product is eliminated in the future, the GGD (fixed wiring low-voltage distribution cabinet, G--low-voltage distribution cabinet; G--fixed installation, fixed wiring; D--electric cabinet) type cabinet has good installation flexibility and will not cause installation troubles due to the modification or update of components.

[0038] The impedance cabinet is mainly used to store specially designed impedance network modules 4 and line inductance modules 5.

[0039] The impedance network module 4 adopts a modular design. The impedance network module 4 includes inductors, capacitors, resistors and circuit boards with capacitors of various specifications, which are used to simulate complex power grid circuits with different lengths and different wiring methods. The topological structure diagram of the impedance network module 4 is shown in FIG. Figure 5 As shown. The impedance network module 4 is modularly designed based on the topological structure diagram specified in the national standard, and different parameters and quantities are assigned to resistors, inductors, and capacitors of various specifications, and the appearance is unified, thereby greatly increasing the compatibility between impedance network modules, while also reducing processing costs and improving operability. However, due to the different parameters of inductors, resistors, capacitors, and circuit boards, the corresponding impedance network modules 4 have different specifications. In this embodiment, the module level and the parallel string form are the same in performance, and combined with the connection method of half-string string and full-string string, the corresponding impedance network module has three different specifications, and the impedance network module parameter settings are shown in the following table.

[0040]

[0041] Similarly, the line inductance module 5 adopts a modular design. The composition of the line inductance module 5 includes several different types of hollow inductors with different parameters, sizes and models, and the parameters can be set according to the specific actual test requirements. There is no relevant description of the line inductance module 5 in the current national standards. Based on the principle of the impedance network module 4 and the parameter description of this system, the topological structure diagram of the line inductance module 5 that can extend the length of the simulated line is shown in the figure below. Figure 6 shown.

[0042] See Figure 4 The impedance network module 4 and the line inductance module 5 are both modularly designed, and an embedded drawer structure is used in the impedance cabinet. The impedance network module 4 and the line inductance module 5 are arranged in the cabinet frame 1 through a connecting piece 7. A mounting hole is arranged on the connecting piece 7. One end of the connecting piece 7 is fixed to the impedance network module 4 and the line inductance module 5, and the other end is connected to the fixed vertical plate 3, which greatly improves the versatility and portability, and is also convenient for later repair and maintenance. A handle 6 is also arranged on the outside, which is more convenient for disassembly and assembly.

[0043] Among them, there is no relevant description for the specific requirements of the impedance network module 4 and the line inductance module 5 in the national standard and the DSF-PREN_IEC_63027 standard, but in the provisions of the 2018 standard UL1699B, there is the following description:

[0044] Component values ​​for arc-fault test circuits

[0045] Representing 80meters of total conductor length,including PV modulewiring for 10modules in A string

[0046] (Corresponding translation: The component values ​​of the arc fault test circuit represent a total wire length of 80 meters, including the wiring of a 10-module photovoltaic panel.)

[0047] However, in actual applications, the wire length of 80 meters cannot completely simulate the actual situation of a photovoltaic power plant. In order to further simulate the photovoltaic power station test more realistically, the number of impedance network modules 4 is increased in this embodiment, and because when the line grows, not only the line impedance increases, but the line reactance also increases, which will affect the high-frequency characteristics of the signal, so based on this, a line inductance module 5 is designed, and two impedance cabinets can be set to work together during the specific test, that is, 24 available impedance network modules 4 and 4 available line inductance modules 5 are set in this embodiment. The impedance network module 4 and the line inductance module 5 are combined and connected through a plug-in connection line and a relay switch group to form different impedance gears. In the simulation test, the impedance network module 4 and the line inductance module 5 with corresponding number and connection mode can be selected and switched for the required test line length. In this embodiment, the length of the simulation test line is 600 meters, which greatly makes up for the shortcomings in the existing standards. Further, in the simulation test, the number of impedance network modules 4 and line inductance modules 5 with corresponding effects can be selected to select and switch the required line length.

[0048] The impedance cabinet provided in this embodiment simulates the line impedance in the actual line through the impedance network module 4 and the line inductance module 5 after the power cabinet outputs the DC power supply as required by the test, and at the same time provides an approximately constant high-voltage impedance to ensure the comparability of different measurement results.

[0049] In short, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An impedance cabinet specially used for photovoltaic DC arc fault protection electrical detection equipment, characterized in that: It comprises a cabinet frame (1) and a side crossbeam (2) arranged on the side of the cabinet frame, the cabinet frame and the side crossbeam are respectively provided with mounting holes arranged according to the module, and the side crossbeam is arranged on the cabinet frame through the mounting holes; The side crossbeam is provided with a fixed vertical plate (3) located inside the cabinet frame, and the front side of the cabinet frame is provided with a front cover plate (109), and the front cover plate is provided with a plurality of openings for accommodating a modular impedance network module (4) and / or a line inductance module (5), and one end of the modular impedance network module and / or the line inductance module away from the front cover plate is fixed to the fixed vertical plate.

2. The impedance cabinet specially used for photovoltaic DC arc fault protection electrical equipment detection equipment according to claim 1 is characterized in that: The impedance network module adopts a modular design, and the components of the impedance network module include inductors, capacitors, resistors of various specifications and a circuit board on which the capacitors are mounted.

3. The impedance cabinet specially used for photovoltaic DC arc fault protection electrical equipment detection equipment according to claim 1 is characterized in that: The line inductance module adopts a modular design, and the line inductance module comprises a number of air-core inductors of different models.

4. The impedance cabinet specially used for photovoltaic DC arc fault protection electrical equipment detection equipment according to claim 2 or 3, characterized in that: A handle (6) is provided on the front of the impedance network module or the line inductance module.

5. The impedance cabinet specially used for photovoltaic DC arc fault protection electrical equipment detection equipment according to claim 4 is characterized in that: The impedance network module or the line inductance module is fixed in the cabinet frame via a connecting piece (7), one end of the connecting piece is fixed on the impedance network module or the line inductance module, and the other end is connected to the fixed vertical plate.

6. The impedance cabinet specially used for photovoltaic DC arc fault protection electrical equipment detection equipment according to claim 1 is characterized in that: The bottom of the cabinet frame is fixedly provided with movable casters (107) at the four corners; the top of the cabinet frame is fixedly provided with a top plate (108); and the left and right sides of the cabinet frame are provided with sealing plates.

7. The impedance cabinet specially used for photovoltaic DC arc fault protection electrical equipment detection equipment according to claim 1 is characterized in that: A rear door (106) with a double-door structure is symmetrically arranged on the rear side of the cabinet frame, a shutter is provided on the rear door, and the rear door is hinged to the cabinet frame.

8. The impedance cabinet specially used for photovoltaic DC arc fault protection electrical equipment detection equipment according to claim 1 is characterized in that: The front sealing plate is in a box-shaped structure as a whole, and is installed in an embedded manner.

9. The impedance cabinet specially used for photovoltaic DC arc fault protection electrical equipment detection equipment according to claim 1 is characterized in that: The side cross beam is in a C-shaped structure, and the three sides of the C-shaped structure are respectively provided with mounting holes arranged according to a preset rule.

10. The impedance cabinet specially used for photovoltaic DC arc fault protection electrical equipment detection equipment according to claim 1, characterized in that: The fixed vertical plate is in an L-shaped structure, and mounting holes arranged according to a preset rule are respectively arranged on two side surfaces of the L-shaped structure.

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