A photovoltaic power generation DC side arc protection system

Abstract

This invention discloses a DC-side arc flash protection system for photovoltaic power generation, belonging to the field of arc flash protection technology. The invention includes a cabinet that is electrically connected to the photovoltaic power generation system, and a relay housing is installed inside the cabinet. A terminal block is fixedly installed inside the relay housing, and an insulating frame is fixedly installed on the outside of the terminal block. An electromagnetic component is fixedly installed on the insulating frame, and an armature is rotatably mounted on the insulating frame. A gear is rotatably mounted on the armature, and a moving contact is fixedly installed on the outside of the gear. A stationary contact is fixedly installed on the terminal block, and an arc-extinguishing grid for assisting arc extinguishing is provided on the terminal block. A secondary drive mechanism for driving the moving contact to rotate is also installed on the armature. This DC-side arc flash protection system for photovoltaic power generation can achieve arc extinguishing operation of the photovoltaic system through rapid power outage, and has a secondary adjustment mechanism to effectively avoid contact adjustment failures, improving the system's operational safety.

Description

Technical Field

[0001] This invention relates to the field of arc flash protection technology, specifically to an arc flash protection system for the DC side of photovoltaic power generation. Background Technology

[0002] Arc faults on the DC side of photovoltaic power generation (such as series arcing, parallel arcing, and ground arcing) are characterized by high energy, rapid development, and great harm. The high temperature (up to 20,000℃), strong light, and explosive pressure generated may cause equipment burnout, fire, or even personal injury. Therefore, arc protection systems are needed to ensure the stability and safety of photovoltaic power generation systems.

[0003] Prior art (Chinese patent publication number: CN119008343A, publication date: 2024-11-22) discloses a photovoltaic power generation DC arc flash protection system. This system uses a power-off device, including: a cabinet with a first connector and a second connector installed at its bottom and top respectively; it also includes: an adjustment cavity embedded in the middle of the lower terminal block, an electric push rod assembly mounted on the adjustment cavity, and a first liquid cavity and a second liquid cavity that are interconnected within the adjustment cavity, with the push rod movably installed in the first liquid cavity; and an electromagnetic drive component disposed in the second liquid cavity, which uses the principle of current increase due to the arc flash effect to drive the energized connector to move and disconnect the power. This photovoltaic power generation DC arc flash protection system utilizes the current change during the arc flash phenomenon to enable the circuit breaker component of the system to quickly self-start, allowing the system to quickly disconnect the circuit, achieving arc flash protection and improving the safety of circuit use.

[0004] The prior art (Chinese patent No. CN211182105U, published on 2020-08-04) discloses an arc-extinguishing relay, including a housing and a magnetic circuit assembly, a moving contact and a stationary contact disposed inside the housing. A contact area is formed between the moving contact and the stationary contact for them to make contact to switch on and off. A magnet is provided inside the housing near the contact area, which can reduce the damage to the contacts caused by electric arc sparks, thereby extending the service life of the relay.

[0005] Existing photovoltaic power generation DC-side arc protection systems rely on a single adjustment method for relay contacts during arc extinguishing operations. This limits the contact adjustment to a single direction, and the driving method is fixed, mostly using electromagnetic drive. However, during long-term use, when high current or high voltage is applied or removed, an electric arc is generated between the contacts. The high temperature (up to several thousand degrees Celsius) causes localized melting of the metal on the contact surface, resulting in "fusion welding" adhesion upon cooling. Furthermore, the oxide film on the surface of the contacts gradually thickens over time, and "cold welding" (intermolecular bonding) occurs due to minute deformation between the contacts, making adjustment impossible. The single contact adjustment method cannot effectively remedy the situation after contact adjustment failure, further increasing the damage of the equipment caused by arcing and compromising safety, thus exhibiting certain operational defects. Summary of the Invention

[0006] The purpose of this invention is to provide a DC-side arc flash protection system for photovoltaic power generation, in order to solve the problem mentioned in the background art that the single contact adjustment method of the current photovoltaic DC-side arc flash protection system on the market cannot effectively remedy the situation after the contact adjustment fails, thereby causing the arc flash to further aggravate the damage to the equipment.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a DC-side arc protection system for photovoltaic power generation. This system uses a power-off device, including a cabinet connected to the photovoltaic power generation system. A control panel is installed on the front side of the cabinet, and a relay housing is installed inside the cabinet. A terminal block is fixedly installed inside the relay housing, and an insulating frame is fixedly installed on the outer side of the terminal block. An electromagnetic component is fixedly installed on the insulating frame, and an armature is rotatably mounted on the insulating frame. A gear is rotatably mounted on the armature, and a moving contact is fixedly installed on the outer side of the gear. A stationary contact is fixedly installed on the terminal block, and an arc-extinguishing grid for assisting arc extinguishing is provided on the terminal block. A secondary drive mechanism for driving the moving contact to rotate is also installed on the armature.

[0008] Preferably, a reset spring is connected between the terminal block and the insulating frame, and the electromagnetic component attracts the armature by magnetic force. The electromagnetic component and the armature are arranged in a perpendicular and corresponding manner. During the rotation of the armature, the moving contact on its outer side is disengaged from the stationary contact to achieve circuit disconnection.

[0009] Preferably, the arc-extinguishing grid includes uniformly parallel metal arc-extinguishing plates, and the arc-extinguishing grid is located outside the moving contact, and the arc-extinguishing grid divides the electric arc into multiple short arcs in series.

[0010] Preferably, the secondary drive mechanism includes a high-voltage chamber fixedly installed on the outside of the armature, and an igniter is installed on the inside of the high-voltage chamber. The spring of the moving contact is made of elastic material, and a traction rope is connected between the spring of the moving contact and the switch of the igniter. During the rotation of the armature, the moving contact spring undergoes elastic bending, and the traction rope pulls the switch of the igniter to open.

[0011] Preferably, the high-pressure chamber is made of a high-temperature and high-pressure resistant material, and sodium azide tablets are placed inside the high-pressure chamber, and the sodium azide tablets are heated and reacted when the igniter is started.

[0012] Preferably, an air guide cylinder is fixedly connected to the outer side of the high-pressure chamber, and the inner spaces of the high-pressure chamber and the air guide cylinder are connected. A piston block is slidably connected to the inner side of the air guide cylinder with an interference fit. A telescopic rod is fixedly connected to the outer side of the piston block, and a first spring is fixedly connected between the piston block and the inner wall of the end of the air guide cylinder. The piston block will push the telescopic rod to extend and retract under the action of air pressure.

[0013] Preferably, a rack is fixedly connected to one end of the telescopic rod located outside the air guide cylinder, and the rack and gear are meshed together. During the movement of the telescopic rod and the rack, the gear and the moving contact are rotated through the meshing action, and the moving contact disengages from the stationary contact after rotating.

[0014] Preferably, an exhaust pipe is also connected to the outside of the high-pressure chamber, and the port of the exhaust pipe faces the arc-extinguishing grid. The end of the exhaust pipe near the arc-extinguishing grid is connected to a frustum-shaped sealing plug through a second spring, and the sealing plug seals the exhaust pipe. A pressure relief valve is also installed on the relay housing.

[0015] Preferably, an elastic grinding disc is installed on the outermost arc-extinguishing plate of the arc-extinguishing grid, and the elastic grinding disc has an arc-shaped structure and is located on the rotation path of the moving contact. At the same time, the elastic grinding disc removes the oxide layer on the outer side of the moving contact during the rotation of the moving contact.

[0016] Compared with the prior art, the beneficial effects of the present invention are: the DC side arc protection system for photovoltaic power generation can realize the arc extinguishing operation of the photovoltaic system through rapid power outage, and has a secondary adjustment mechanism to effectively avoid contact adjustment failures and improve the safety of system use, as detailed below;

[0017] 1. Equipped with an electromagnetic component and an armature, when an arc fault is detected in the photovoltaic power generation system, the electromagnetic component is activated to attract the armature, which in turn drives the moving contact to rotate via a spring, thereby causing the moving contact to detach from the outside of the stationary contact, achieving rapid circuit disconnection and thus extinguishing the arc.

[0018] 2. Equipped with gears, a high-pressure chamber, a gas guide cylinder, and a rack, when the moving contact malfunctions during adjustment and cannot separate from the stationary contact, the spring on the moving contact will undergo elastic deformation, causing it to pull the igniter switch via a traction rope. This allows the igniter to heat the sodium azide tablets pre-stored inside the high-pressure chamber, rapidly generating a large amount of nitrogen gas. Under the action of gas pressure, the piston block pushes the telescopic rod and rack to move at high speed. The rack drives the gear to rotate through meshing, causing the moving contact to rotate elastically outside the armature, thus separating the moving contact from the stationary contact.

[0019] Furthermore, an exhaust pipe and a sealing plug are also provided. The exhaust pipe and sealing plug can be used to regulate the air pressure inside the high-pressure chamber to prevent excessive air pressure inside the high-pressure chamber from causing an explosion. The nitrogen gas generated by the reaction inside the high-pressure chamber is blown towards the arc-extinguishing grid through the exhaust pipe.

[0020] An arc-extinguishing grid is provided. When an electric arc is generated between the moving and stationary contacts, the arc-extinguishing grid can divide the arc into multiple short arcs in series, thereby eliminating the arc.

[0021] Furthermore, an arc-extinguishing grid is also provided. When the moving contact is rotated and adjusted after a fault, the moving contact will move closer to the elastic grinding disc installed on the outermost arc-extinguishing plate. At this time, the elastic grinding disc can rub and remove the oxide layer on the moving contact. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the main structure of the present invention;

[0023] Figure 2 This is a schematic diagram of the relay housing mounting structure of the present invention;

[0024] Figure 3 This is a schematic cross-sectional view of the relay housing structure of the present invention;

[0025] Figure 4 This is a schematic diagram of the connection structure between the insulating frame and the armature of the present invention;

[0026] Figure 5 This is a schematic diagram of the gear and arc-extinguishing grid installation structure of the present invention;

[0027] Figure 6 This is a schematic diagram of the connection structure between the moving contact and the stationary contact of the present invention;

[0028] Figure 7 This is a schematic diagram of the gear and rack connection structure of the present invention;

[0029] Figure 8 This is a schematic cross-sectional view of the high-pressure chamber of the present invention;

[0030] Figure 9This is a schematic diagram of the three-dimensional structure of the arc-extinguishing grid of the present invention.

[0031] In the diagram: 1. Cabinet; 2. Control panel; 3. Relay housing; 4. Terminal block; 5. Insulating frame; 6. Electromagnetic assembly; 7. Armature; 8. Return spring; 9. Gear; 10. Moving contact; 11. Stationary contact; 12. Arc extinguishing grid; 13. Elastic grinding disc; 14. High-pressure chamber; 15. Ignition device; 16. Traction rope; 17. Air guide tube; 18. Piston block; 19. Telescopic rod; 20. First spring; 21. Rack; 22. Exhaust pipe; 23. Sealing plug; 24. Second spring; 25. Pressure relief valve. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1: Existing photovoltaic power generation DC-side arc flash protection system. To solve this technical problem, this example discloses the following technical content. Please refer to [link / reference]. Figures 1-5 As shown; a photovoltaic power generation DC side arc flash protection system, the system uses a power-off device, including a cabinet 1 that is electrically connected to the photovoltaic power generation system, a control panel 2 installed on the front of the cabinet 1, and a relay housing 3 installed inside the cabinet 1; a terminal block 4 is fixedly installed inside the relay housing 3, and an insulating frame 5 is fixedly installed on the outside of the terminal block 4, and an electromagnetic component 6 is fixedly installed on the insulating frame 5. An armature 7 is rotatably mounted on the insulating frame 5, a gear 9 is rotatably mounted on the armature 7, and a moving contact 10 is fixedly installed on the outside of the gear 9. The terminal block 4... A stationary contact 11 is fixedly installed on the terminal block 4, and an arc-extinguishing grid 12 for assisting in arc extinguishing is provided on the terminal block 4. A return spring 8 is connected between the terminal block 4 and the insulating frame 5. The electromagnetic component 6 attracts the armature 7 through magnetic force. The electromagnetic component 6 and the armature 7 are vertically corresponding. During the rotation of the armature 7, the moving contact 10 on its outer side is disengaged from the stationary contact 11 to realize the circuit disconnection. The arc-extinguishing grid 12 includes uniformly parallel metal arc-extinguishing plates. The arc-extinguishing grid 12 is located outside the moving contact 10 and divides the electric arc into multiple short arcs in series.

[0034] The cabinet 1 integrates a power supply module, CPU module, arc light acquisition module, DC current and voltage acquisition module, AC current and voltage acquisition module, input / output module, communication module, and human-machine interface module. It integrates multiple functions such as protection, measurement, monitoring, control, communication, fault recording, and event recording. It monitors arc light signals and AC / DC protection current or voltage signals in real time to realize the DC arc light protection function of the photovoltaic inverter cabinet. When the arc light acquisition module, DC current and voltage acquisition module, and AC current and voltage acquisition module detect an arc light fault, the electromagnetic component 6 is activated. The electromagnetic component 6 attracts the armature 7 through magnetic force, causing the armature 7 to rotate elastically on the insulating frame 5. This causes the moving contact 10 on its outer side to move, separating the moving contact 10 from the stationary contact 11, thereby cutting off the circuit and realizing the arc light protection function of the photovoltaic inverter cabinet. When an arc is generated between the moving contact 10 and the stationary contact 11, the arc extinguishing grid 12 can introduce the arc, thereby dividing the arc into multiple short arcs in series, achieving an auxiliary arc extinguishing effect.

[0035] Example 2: The technical content disclosed in this example is a further improvement based on Example 1. Existing photovoltaic power generation DC-side arc flash protection systems use a single contact adjustment method in their relays, which cannot effectively remedy contact adjustment failures. To further solve this technical problem, this example discloses the following technical content: Figures 4-8As shown; a secondary drive mechanism for driving the moving contact 10 to rotate is also installed on the armature 7. The secondary drive mechanism includes a high-voltage chamber 14 fixedly installed on the outside of the armature 7, and an igniter 15 is installed on the inside of the high-voltage chamber 14. The spring of the moving contact 10 is made of elastic material, and a traction rope 16 is connected between the spring of the moving contact 10 and the switch of the igniter 15. During the rotation of the armature 7, when the spring of the moving contact 10 elastically bends, the traction rope 16 pulls the switch of the igniter 15 to open. The high-voltage chamber 14 is made of durable material. Made of high-temperature, high-pressure materials, the high-pressure chamber 14 contains sodium azide tablets, which are heated and reacted when the igniter 15 is activated. A gas guide cylinder 17 is fixedly connected to the outside of the high-pressure chamber 14, and the inner spaces of the high-pressure chamber 14 and the gas guide cylinder 17 are connected. A piston block 18 is interference-fitted to the inside of the gas guide cylinder 17, and a telescopic rod 19 is fixedly connected to the outside of the piston block 18. A first spring is fixedly connected between the piston block 18 and the inner wall of the end of the gas guide cylinder 17. 20. The piston block 18 will push the telescopic rod 19 to extend and retract under air pressure. A rack 21 is fixedly connected to one end of the telescopic rod 19 located outside the air guide cylinder 17, and the rack 21 meshes with the gear 9. During the movement of the telescopic rod 19 and the rack 21, the meshing action drives the gear 9 and the moving contact 10 to rotate. Simultaneously, after rotating, the moving contact 10 disengages from the stationary contact 11. An exhaust pipe 22 is also connected to the outside of the high-pressure chamber 14, with the port of the exhaust pipe 22 facing the arc-extinguishing grille 12. One end of the vent pipe 22 near the arc-extinguishing grid 12 is elastically connected to a frustum-shaped sealing plug 23 via a second spring 24. The sealing plug 23 seals the vent pipe 22. A pressure relief valve 25 is also installed on the relay housing 3. An elastic grinding plate 13 is installed on the outermost arc-extinguishing plate of the arc-extinguishing grid 12. The elastic grinding plate 13 has an arc-shaped structure and is located on the rotation path of the moving contact 10. During the rotation of the moving contact 10, the elastic grinding plate 13 grinds off the oxide layer on its outer side.

[0036] When the moving contact 10 and the stationary contact 11 become stuck together and cannot be separated for adjustment, the spring on the moving contact 10 will undergo elastic deformation under the pull of the armature 7. This causes the traction rope 16 connected to the moving contact 10 to pull the switch on the igniter 15, activating the igniter 15 and heating the sodium azide tablets inside the high-pressure chamber 14. The sodium azide reacts rapidly upon heating, generating a large amount of gas. The generated nitrogen gas quickly fills the high-pressure chamber 14 and pushes the piston block 18 inside the gas guide cylinder 17 to slide and adjust. This causes the piston block 18 to drive the rack 21 synchronously through the telescopic rod 19. During the movement of the rack 21, the meshing action drives the gears... The rotation of wheel 9 causes gear 9 to drive the fixed moving contact 10 on its outer side to rotate laterally. Under the action of high pressure gas, the rotation speed of moving contact 10 is relatively large, which can achieve separation from stationary contact 11 and avoid further aggravation of arc fault. At the same time, sealing plug 23 will open under the action of air pressure, so that excess nitrogen in high pressure chamber 14 will be blown to arc extinguishing grid 12 through exhaust pipe 22, thereby assisting arc extinguishing in conjunction with arc extinguishing grid 12. As moving contact 10 rotates laterally, moving contact 10 will adhere to and pass through elastic grinding disc 13 on arc extinguishing grid 12, so that elastic grinding disc 13 can remove oxides on the outer side of moving contact 10 to improve the contact stability of moving contact 10 in the future.

[0037] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0038] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

Claims

1. A photovoltaic power generation DC side arc protection system, the system using a power-off device, including a cabinet (1) that is electrically connected to the photovoltaic power generation system, a control panel (2) installed on the front side of the cabinet (1), and a relay housing (3) installed inside the cabinet (1). Its features are, The relay housing (3) is fixedly installed with a terminal block (4) inside, and an insulating frame (5) is fixedly installed on the outside of the terminal block (4). An electromagnetic component (6) is fixedly installed on the insulating frame (5). An armature (7) is rotatably installed on the insulating frame (5). A gear (9) is rotatably installed on the armature (7). A moving contact (10) is fixedly installed on the outside of the gear (9). A stationary contact (11) is fixedly installed on the terminal block (4). An arc-extinguishing grid (12) is provided on the terminal block (4) to assist in arc extinguishing. A secondary drive mechanism for driving the moving contact (10) to rotate is also installed on the armature (7). The secondary drive mechanism includes a high-voltage chamber (14) fixedly installed on the outside of the armature (7), and an igniter (15) is installed on the inside of the high-voltage chamber (14). The spring of the moving contact (10) is made of elastic material, and a traction rope (16) is connected between the spring of the moving contact (10) and the switch of the igniter (15). When the spring of the moving contact (10) is elastically bent during the rotation of the armature (7), the traction rope (16) pulls the switch of the igniter (15) to start. The high-pressure chamber (14) is made of high-temperature and high-pressure resistant material, and sodium azide tablets are placed inside the high-pressure chamber (14), and the sodium azide tablets are heated and reacted when the igniter (15) is started. The high-pressure chamber (14) is fixedly connected to the outer side of the air guide cylinder (17), and the inner spaces of the high-pressure chamber (14) and the air guide cylinder (17) are connected. The inner side of the air guide cylinder (17) is connected to the piston block (18) with interference sliding. At the same time, the outer side of the piston block (18) is fixedly connected to the telescopic rod (19), and a first spring (20) is fixedly connected between the inner wall of the piston block (18) and the end of the air guide cylinder (17). The piston block (18) will push the telescopic rod (19) to extend and retract under the action of air pressure. The telescopic rod (19) is fixedly connected to a rack (21) at one end outside the air guide cylinder (17), and the rack (21) and the gear (9) are meshed together. During the process of the telescopic rod (19) driving the rack (21) to move, the gear (9) and the moving contact (10) are rotated through the meshing action. At the same time, the moving contact (10) disengages from the stationary contact (11) after rotating.

2. The photovoltaic power generation DC-side arc flash protection system according to claim 1, characterized in that: A reset spring (8) is connected between the terminal block (4) and the insulating frame (5), and the electromagnetic component (6) attracts the armature (7) through magnetic force. The electromagnetic component (6) and the armature (7) are vertically aligned. During the rotation of the armature (7), the moving contact (10) on its outer side is disengaged from the stationary contact (11) to achieve circuit disconnection.

3. The photovoltaic power generation DC-side arc flash protection system according to claim 1, characterized in that: The arc-extinguishing grid (12) includes uniformly parallel metal arc-extinguishing plates, and the arc-extinguishing grid (12) is located outside the moving contact (10), and the arc-extinguishing grid (12) divides the electric arc into multiple short arcs in series.

4. The photovoltaic power generation DC-side arc flash protection system according to claim 1, characterized in that: The high-pressure chamber (14) is also connected to an exhaust pipe (22), and the port of the exhaust pipe (22) faces the arc-extinguishing grid (12). The end of the exhaust pipe (22) near the arc-extinguishing grid (12) is elastically connected to a frustum-shaped sealing plug (23) through a second spring (24). At the same time, the sealing plug (23) seals the exhaust pipe (22). A pressure relief valve (25) is also installed on the relay housing (3).

5. The photovoltaic power generation DC-side arc flash protection system according to claim 1, characterized in that: An elastic grinding disc (13) is installed on the outermost arc-extinguishing plate of the arc-extinguishing grid (12). The elastic grinding disc (13) has an arc-shaped structure and is located on the rotation path of the moving contact (10). At the same time, the elastic grinding disc (13) grinds off the oxide layer on the outer side of the moving contact (10) during the rotation process.

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