Photovoltaic feed system protection device and method

Abstract

A photovoltaic feed system protection device comprises three overvoltage protection modules, and each module comprises a metal shell, a grounding terminal, a high-voltage bushing, a first gas discharge bulb, a second gas discharge bulb, a first lamp holder, a second lamp holder, a first shunt diode, a second shunt diode, a first capacitor, a second capacitor and a fly ash filler. A first gas discharge bulb and a second gas discharge bulb are respectively mounted on the first lamp holder and the second lamp holder; one electrode of the first lamp holder is connected with the metal shell through a first capacitor, and one electrode of the second lamp holder is connected with the metal shell through a second capacitor; and the first shunt diode and the second shunt diode are connected in series between the other electrode of the end part of the first lamp holder and the other electrode of the end part of the second lamp holder in the same direction. According to the invention, overvoltage protection of the maximum through-current capability of sensitive equipment such as a photovoltaic inverter is realized; and power frequency follow current can be cut off, and the circuit has the advantages of low residual voltage, low protection speed and low cost.

Description

Technical Field

[0001] The present invention relates to the field of power grid protection, and in particular to a photovoltaic feeder system protection device and method. Background Art

[0002] Photovoltaic inverters have a weak ability to withstand lightning overvoltage, and existing overvoltage protection devices often cannot provide good protection. Existing overvoltage protection technologies include: The patent with application number CN202210860750.0 discloses a contact network over-phase transient overvoltage protection device based on edge computing. The operating status of capacitor C1 is obtained by measuring current and temperature in combination with edge computing. At the same time, lightning arrester F1 and lightning arrester monitor J1 are connected between the high-voltage bus M and the ground. While lightning arrester F1 absorbs the transient overvoltage generated by the over-phase, lightning arrester monitor J1 monitors the operating status of lightning arrester F1, and uses resistors and inductors in parallel to consume overvoltage energy, while capacitors are connected in series to limit overvoltage. However, this method uses zinc oxide lightning arresters. After the zinc oxide lightning arrester is activated, it cannot form a negative resistance characteristic, and the residual voltage is high. Generally, the residual voltage will reach 2 times the rated voltage, which cannot protect photovoltaic equipment with power electronic components as the main components. Application number CN202122229958.6 provides an active fault-cutting gas discharge tube and overvoltage protection device, which includes a first insulating tube body, two electrodes and two connectors. The two electrodes are respectively arranged at the two ends of the first insulating tube body, and together with the first insulating tube body, form a discharge cavity. The surfaces of the two electrodes facing the discharge cavity form a discharge surface; each connector is clamped between the corresponding electrode and the first insulating tube body, and is used to seal and connect the corresponding electrode to the first insulating tube body. Both connectors are provided with a high-temperature connection part, and at least one of the two connectors is also provided with a low-temperature connection part. The low-temperature connection part is connected to the high-temperature connection part end to end in a ring shape, and the melting point of the low-temperature connection part is lower than the melting point of the high-temperature connection part. However, the gas discharge tube has no arc extinguishing ability. Once the breakdown discharge cannot restore the insulation, it will cause the equipment to trip, and the use limitations are also very large. The patent with application number CN202021266132.6 proposes a power supply circuit using an overvoltage protector. It includes a bidirectional thyristor and a bidirectional transient voltage suppression diode. One end of the bidirectional transient voltage suppression diode is connected to the control stage of the bidirectional thyristor, and the other end is connected to the second anode of the bidirectional thyristor; the two anodes of the bidirectional thyristor are the two pins of the protector. However, the transient voltage suppression diode has the defect of small current carrying capacity, generally only a few kiloamperes, which cannot meet the lightning protection current carrying capacity requirements of the busbar of large photovoltaic equipment. Summary of the invention

[0003] In order to solve the deficiencies in the prior art, the present invention provides a photovoltaic feeding system protection device.

[0004] The present invention adopts the following technical solution.

[0005] The first aspect of the present invention provides a photovoltaic feeder system protection device, comprising three identical overvoltage protection modules 9, each module comprising a metal housing 1, a grounding terminal 2, a high-voltage bushing 3, a first gas discharge bulb 41 and a second gas discharge bulb 42, a first lamp holder 51, a second lamp holder 52, a first shunt diode 61, a second shunt diode 62 and a fly ash filler 8; specifically: The three overvoltage protection modules 9 are respectively connected to the ABC three-phase lines of the protected photovoltaic feeder system; The metal shell 1 of the overvoltage protection module 9 is an airtight structure, and is filled with fly ash filler 8; the high-voltage bushing 3 is arranged on the top of the metal shell 1, and the first lamp holder 51 and the second lamp holder 52 are respectively insulated and sealed on the metal shells on both sides of the high-voltage bushing 3, and the first gas discharge bulb 41 and the second gas discharge bulb 42 are respectively installed on the corresponding first lamp holder and the second lamp holder; One electrode of the first lamp holder 51 is connected to the metal housing 1, and one electrode of the second lamp holder 52 is connected to the metal housing 1; the first shunt diode 61 and the second shunt diode 62 are connected in series in the same direction between the other electrode at the end of the first lamp holder 51 and the other electrode at the end of the second lamp holder 52; One end of the wire passing through the high-voltage bushing 3 is connected to the corresponding phase line of the protected photovoltaic feeder system, and the other end is connected between the first shunt diode 61 and the second shunt diode 62; The metal housing 1 is connected to a grounding grid via a grounding terminal 2 .

[0006] Preferably, the overvoltage protection module 9 includes a first capacitor 71 and a second capacitor 72 , an electrode of the first lamp holder 51 is connected to the metal housing 1 via the first capacitor 71 , and an electrode of the second lamp holder 52 is connected to the metal housing 1 via the second capacitor 72 .

[0007] Preferably, the first gas discharge bulb 41 and the second gas discharge bulb 42 are both metal halide bulbs.

[0008] Preferably, the first gas discharge bulb 41 and the second gas discharge bulb 42 have the same specifications and are both provided with auxiliary electrodes.

[0009] Preferably, the metal shell 1 is an airtight structure capable of withstanding an air pressure of 2 MPa.

[0010] Preferably, the first shunt diode 61 and the second shunt diode 62 have the same model and specification, and their rated instantaneous current is not less than 10KA.

[0011] Preferably, the first capacitor 71 and the second capacitor 72 are metal film impact capacitors of the same specification, and the capacity thereof is 1 uF.

[0012] Preferably, the conductor lead at the end of the first lamp holder 51 is connected to the first capacitor 71 , and the conductor lead at the end of the second lamp holder 52 is connected to the second capacitor 72 .

[0013] Preferably, the first shunt diode 61 and the second shunt diode 62 are connected in series in the same direction between the screw-type conductive part of the first lamp holder 51 and the screw-type conductive part of the second lamp holder 52 .

[0014] The second aspect of the present invention provides a photovoltaic feeder system protection method using the protection device according to the first aspect of the present invention, comprising: When the photovoltaic feeding system is subjected to overvoltage, the overvoltage of the corresponding phase line of the photovoltaic feeding system is connected to the first shunt diode 61 and the second shunt diode 62 through the high-voltage bushing 3; The AC overvoltage is divided into two half-waves by the first shunt diode 61 and the second shunt diode 62 and respectively given to the first gas discharge bulb 41 and the second gas discharge bulb 42, so as to give the gas in the two gas discharge bulbs time to deionize and extinguish the arc; and the first capacitor 71 and the second capacitor 72 are used to maintain the electrode ion state of the gas discharge bulb; after the overvoltage is transmitted to the first gas discharge bulb 41 and the second gas discharge bulb 42, gas breakdown discharge protection is performed.

[0015] The beneficial effect of the present invention is that, compared with the prior art, The present invention utilizes the gas discharge of the metal halide lamp bulb, which has a large current capacity and can realize the overvoltage protection of the extremely large current capacity of sensitive equipment such as photovoltaic feeder system; the present invention further divides the AC voltage into two half-waves and gives them to two bulbs respectively through the shunt diode. The power frequency continuous current can interrupt half a cycle of 10 milliseconds due to the isolation effect of the shunt diode, giving the gas in the metal halide lamp bulb enough time to deionize and extinguish the arc, so that the power frequency continuous current is cut off and will not cause tripping; because the present invention is a gas breakdown protection, the residual pressure after the overvoltage intrusion wave breaks through the gas is very low; the present invention further realizes the continuous maintenance of the electrode ion state inside the arc tube under the power frequency voltage through the voltage maintenance effect of the first capacitor and the second capacitor, combined with the arc tube discharge effect of the existing starting resistor of the bulb, so as to further improve the protection action speed to the nanosecond level. In addition, the present invention uses scrapped light source devices, which can be repaired by replacing new bulbs after being struck by lightning and aging, and have very low use and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a structural diagram of an embodiment of the present invention; Figure 2 4 is a structural diagram of an overvoltage protection module in an embodiment of the present invention. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only embodiments of a part of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0018] like Figure 1 As shown, embodiment 1 of the present invention proposes a photovoltaic feeder system protection device, including three identical overvoltage protection modules 9, each module including a metal shell 1, a grounding terminal 2, a high-voltage bushing 3, a first gas discharge bulb 41 and a second gas discharge bulb 42, a first lamp holder 51, a second lamp holder 52, a first shunt diode 61, a second shunt diode 62 and a fly ash filler 8; specifically: like Figure 2 As shown, three overvoltage protection modules 9 are respectively connected to the ABC three-phase lines of the protected photovoltaic feeder system; The metal shell 1 of the overvoltage protection module 9 is an airtight structure, and is filled with fly ash filler 8; the high-voltage bushing 3 is arranged on the top of the metal shell 1, and the first lamp holder 51 and the second lamp holder 52 are respectively insulated and sealed on the metal shells on both sides of the high-voltage bushing 3, and the first gas discharge bulb 41 and the second gas discharge bulb 42 are respectively installed on the corresponding first lamp holder and the second lamp holder; One electrode of the first lamp holder 51 is connected to the metal housing 1, and one electrode of the second lamp holder 52 is connected to the metal housing 1; the first shunt diode 61 and the second shunt diode 62 are connected in series in the same direction between the other electrode at the end of the first lamp holder 51 and the other electrode at the end of the second lamp holder 52; One end of the wire passing through the high-voltage bushing 3 is connected to the corresponding phase line of the protected photovoltaic feeder system, and the other end is connected between the first shunt diode 61 and the second shunt diode 62; The metal housing 1 is connected to a grounding grid via a grounding terminal 2 .

[0019] Preferably, the overvoltage protection module 9 includes a first capacitor 71 and a second capacitor 72 , an electrode of the first lamp holder 51 is connected to the metal housing 1 via the first capacitor 71 , and an electrode of the second lamp holder 52 is connected to the metal housing 1 via the second capacitor 72 .

[0020] Preferably, the first gas discharge bulb 41 and the second gas discharge bulb 42 are both metal halide bulbs.

[0021] Preferably, the first gas discharge bulb 41 and the second gas discharge bulb 42 have the same specifications and are both provided with auxiliary electrodes.

[0022] Preferably, the metal shell 1 is an airtight structure capable of withstanding an air pressure of 2 MPa.

[0023] Preferably, the first shunt diode 61 and the second shunt diode 62 have the same model and specification, and their rated instantaneous current is not less than 10KA.

[0024] Preferably, the first capacitor 71 and the second capacitor 72 are metal film impact capacitors of the same specification, and the capacity thereof is 1 uF.

[0025] Preferably, the conductor lead at the end of the first lamp holder 51 is connected to the first capacitor 71 , and the conductor lead at the end of the second lamp holder 52 is connected to the second capacitor 72 .

[0026] Preferably, the first shunt diode 61 and the second shunt diode 62 are connected in series in the same direction between the screw-type conductive part of the first lamp holder 51 and the screw-type conductive part of the second lamp holder 52 .

[0027] Embodiment 2 of the present invention proposes a photovoltaic feeder system protection method using the protection device described in Embodiment 1 of the present invention, comprising: When the photovoltaic feeding system is subjected to overvoltage, the overvoltage of the corresponding phase line of the photovoltaic feeding system is connected to the first shunt diode 61 and the second shunt diode 62 through the high-voltage bushing 3; The AC overvoltage is divided into two half-waves by the first shunt diode 61 and the second shunt diode 62 and respectively given to the first gas discharge bulb 41 and the second gas discharge bulb 42, so as to give the gas in the two gas discharge bulbs time to deionize and extinguish the arc; and the first capacitor 71 and the second capacitor 72 are used to maintain the electrode ion state of the gas discharge bulb; after the overvoltage is transmitted to the first gas discharge bulb 41 and the second gas discharge bulb 42, gas breakdown discharge protection is performed.

[0028] The present disclosure may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0029] A computer-readable storage medium may be a tangible device that can hold and store instructions used by an instruction execution device. A computer-readable storage medium may be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the above. More specific examples (a non-exhaustive list) of computer-readable storage media include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disk read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which instructions are stored, and any suitable combination of the above. The computer-readable storage medium used herein is not to be interpreted as a transient signal itself, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through a wire.

[0030] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, optical fiber transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in the computer-readable storage medium in each computing / processing device.

[0031] The computer program instructions for performing the operations of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages, such as Smalltalk, C++, etc., and conventional procedural programming languages, such as "C" language or similar programming languages. The computer-readable program instructions may be executed entirely on the user's computer, partially on the user's computer, as a separate software package, partially on the user's computer, partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., using an Internet service provider to connect through the Internet). In some embodiments, by using the state information of the computer-readable program instructions to personalize an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), the electronic circuit may execute the computer-readable program instructions, thereby implementing various aspects of the present disclosure.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A photovoltaic feeder system protection device, comprising three identical overvoltage protection modules (9), each module comprising a metal housing (1), a grounding terminal (2), a high-voltage bushing (3), a first gas discharge bulb (41), a second gas discharge bulb (42), a first lamp holder (51), a second lamp holder (52), a first shunt diode (61), a second shunt diode (62) and fly ash filler (8); characterized in that: The three overvoltage protection modules (9) are respectively connected to the ABC three-phase lines of the protected photovoltaic power feeder system; The metal shell (1) of the overvoltage protection module (9) is an airtight structure, and is filled with fly ash filler (8); the high-voltage bushing (3) is arranged on the top of the metal shell (1), and a first lamp holder (51) and a second lamp holder (52) are respectively installed in an insulated and sealed manner on the metal shells on both sides of the high-voltage bushing (3), and a first gas discharge bulb (41) and a second gas discharge bulb (42) are respectively installed on the corresponding first lamp holder and second lamp holder; An electrode of the first lamp holder (51) is connected to the metal housing (1), and an electrode of the second lamp holder (52) is connected to the metal housing (1); the first shunt diode (61) and the second shunt diode (62) are connected in series in the same direction between another electrode at the end of the first lamp holder (51) and another electrode at the end of the second lamp holder (52); One end of the wire passing through the high-voltage bushing (3) is connected to the corresponding phase line of the protected photovoltaic feeder system, and the other end is connected between the first shunt diode (61) and the second shunt diode (62); The metal housing (1) is connected to a grounding grid via a grounding terminal (2).

2. The photovoltaic feeder system protection device according to claim 1, characterized in that: The overvoltage protection module (9) comprises a first capacitor (71) and a second capacitor (72); an electrode of the first lamp holder (51) is connected to the metal housing (1) via the first capacitor (71); and an electrode of the second lamp holder (52) is connected to the metal housing (1) via the second capacitor (72).

3. The photovoltaic feeder system protection device according to claim 1, characterized in that: The first gas discharge bulb (41) and the second gas discharge bulb (42) are both metal halide bulbs.

4. The photovoltaic feeder system protection device according to claim 3, characterized in that: The first gas discharge bulb (41) and the second gas discharge bulb (42) have the same specifications and are both provided with auxiliary electrodes.

5. The photovoltaic feeder system protection device according to claim 1, characterized in that: The metal casing (1) is an airtight structure capable of withstanding an air pressure of 2 MPa.

6. The photovoltaic feeder system protection device according to claim 1, characterized in that: The first shunt diode (61) and the second shunt diode (62) have the same model and specification, and their rated instantaneous passing current is not less than 10KA.

7. The photovoltaic feeder system protection device according to claim 2, characterized in that: The first capacitor (71) and the second capacitor (72) are metal film impact capacitors of the same specification, and their capacity is 1uF.

8. The photovoltaic feeder system protection device according to claim 2, characterized in that: The conductor lead at the end of the first lamp holder (51) is connected to the first capacitor (71), and the conductor lead at the end of the second lamp holder (52) is connected to the second capacitor (72).

9. The photovoltaic feeder system protection device according to claim 2, characterized in that: The first shunt diode (61) and the second shunt diode (62) are connected in series in the same direction between the screw-end conductive part of the first lamp holder (51) and the screw-end conductive part of the second lamp holder (52).

10. A photovoltaic feeder system protection method using the protection device according to any one of claims 1 to 9, characterized in that: include: When the photovoltaic feeder system is subjected to an overvoltage, the overvoltage of the corresponding phase line of the photovoltaic feeder system is connected to the first shunt diode (61) and the second shunt diode (62) through the high-voltage bushing (3); The AC overvoltage is divided into two half-waves by a first shunt diode (61) and a second shunt diode (62) and respectively supplied to a first gas discharge bulb (41) and a second gas discharge bulb (42), so as to provide the gas in the two gas discharge bulbs with arc extinguishing time for deionization; and the first capacitor (71) and the second capacitor (72) are used to maintain the electrode ion state of the gas discharge bulb; after the overvoltage is transmitted to the first gas discharge bulb (41) and the second gas discharge bulb (42), gas breakdown discharge protection is performed.

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