Lightning protection power supply system

Abstract

The invention relates to a lightning protection power supply system, which belongs to the technical field of power supply protection, and comprises an alternating current constant current source, a current main loop and a plurality of power conversion devices, the input end of the alternating-current constant-current source is connected with alternating-current voltage, and the output end of the alternating-current constant-current source is connected with the current main loop; the current main loop comprises a plurality of anti-disconnection switches and current transmission and distribution lines for connecting the anti-disconnection switches in series; the anti-disconnection switch comprises a first terminal, a second terminal, a third terminal and a fourth terminal; the first terminal and the fourth terminal are connected to a current main loop; the second terminal and the third terminal are respectively connected with the first input end and the first output end of the power conversion device; when the first terminal is connected with the second terminal and the third terminal is connected with the fourth terminal, the power conversion device is connected with the current main loop; aC or DC voltage is output between the second input end and the second output end of the power conversion device. The lightning protection device has the effect of reducing the possibility of damage to electric equipment caused by lightning stroke.

Description

Technical Field

[0001] The present application relates to the field of power supply protection, and in particular to a lightning protection power supply system. Background Art

[0002] With the development of the economy, power users have higher and higher requirements for the reliability of power supply in power systems. At present, a low-voltage power supply system with a constant AC voltage is generally used, such as a 220V power supply system. When its transmission lines or electrical equipment are struck by lightning outdoors, the lightning current will generate a large lightning overvoltage, which enters the electrical equipment in a common mode or differential mode, causing damage to the electrical equipment.

[0003] In the current low-voltage power supply system, lightning arresters are usually used to reduce the damage to electrical equipment caused by lightning voltage formed by lightning current. Although lightning arresters can significantly reduce the overvoltage amplitude when lightning strikes, they still cannot fundamentally solve the contradiction between the excessively high lightning residual voltage and the extremely low voltage tolerance of outdoor low-voltage electrical equipment. With the popularization of the Internet of Things, more and more smart electrical equipment is installed outdoors, and the frequency of low-voltage outdoor smart electrical equipment being damaged by lightning is still high. Summary of the invention

[0004] In order to reduce the possibility of damage to electrical equipment caused by lightning strikes, the present application provides a lightning protection power supply system.

[0005] The present application provides a lightning protection power supply system that adopts the following technical solutions:

[0006] A lightning protection power supply system comprises: an AC constant current source, a current main circuit and a plurality of power conversion devices;

[0007] The input end of the AC constant current source is connected to an AC voltage, and the output end of the AC constant current source is connected to the current main loop to provide an AC current to the current main loop;

[0008] The main current circuit includes a plurality of anti-breaking switches and current transmission and distribution lines connecting the anti-breaking switches in series;

[0009] The anti-circuit-break switch comprises a first terminal, a second terminal, a third terminal and a fourth terminal; the first terminal and the fourth terminal are connected to the main current loop; the second terminal is connected to the first input end of the power conversion device, and the third terminal is connected to the first output end of the power conversion device; when the first terminal is connected to the second terminal, and the third terminal is connected to the fourth terminal, the power conversion device is connected to the main current loop;

[0010] An AC or DC voltage is output between the second input terminal and the second output terminal of the power conversion device.

[0011] By adopting the above technical solution, when lightning strikes any position of the main current loop, a lightning voltage will be formed on the main current loop to the ground. If the lightning voltage is too high and causes the weak insulation link of the main current loop to the ground to break down, a lightning current will be formed to discharge to the ground. Since the resistance of the main current loop is very low, even if the lightning current passes through the main current loop partially, the lightning current cannot form an overvoltage on the main current loop and will not affect the normal operation of the main current loop. If the lightning voltage is not sufficient to break down the weak insulation link of the main current loop to the ground, no lightning current will be generated and the operation of the main current loop will not be affected, thereby reducing the possibility of damage to electrical equipment caused by lightning strikes.

[0012] Optionally, the current outputted from the output end of the AC constant current source is an AC sinusoidal wave current with a preset frequency and a preset amplitude.

[0013] Optionally, the frequency of the AC sinusoidal current is a base frequency or an intermediate frequency, the base frequency is 50 Hz or 60 Hz, and the intermediate frequency is 50 Hz-500 Hz.

[0014] By adopting the above technical solution, since high-frequency current is beneficial to the efficiency of power conversion, but the higher the frequency, the greater the line impedance, the frequency of the current is medium frequency, which reduces the line impedance while improving the efficiency of power conversion.

[0015] Optionally, the casing of the power conversion device is grounded.

[0016] By adopting the above technical solution, the casing of the power conversion device is grounded, the lightning current will be directly introduced into the earth, and the residual voltage on the casing is extremely low, which will not endanger the safety of equipment and personnel.

[0017] Optionally, the casing of the AC constant current source is grounded.

[0018] By adopting the above technical solution, the shell of the AC constant current source is grounded, the lightning current will be introduced into the earth, the residual voltage on the shell is extremely low, and will not endanger the safety of equipment and personnel.

[0019] Optionally, the current transmission and distribution line is directly grounded.

[0020] By adopting the above technical solution, when the current transmission and distribution line is directly grounded, the lightning current will be directly introduced into the earth through the current transmission and distribution line. Since the resistance of the current main circuit is very low, no high voltage or a relatively small high voltage is generated, which will not endanger the safety of electrical equipment and personnel around the equipment.

[0021] Optionally, the current transmission and distribution line is indirectly grounded.

[0022] By adopting the above technical solution, when the current transmission and distribution line is indirectly grounded, the lightning current will be indirectly introduced into the earth through the current transmission and distribution line. Since the resistance of the current main circuit is very low, no high voltage or a relatively small high voltage is generated, which will not endanger the safety of electrical equipment and personnel around the equipment.

[0023] Optionally, a low-voltage electrical device is connected between the second input terminal and the second output terminal of the power conversion device.

[0024] In summary, the present application includes at least one of the following beneficial technical effects:

[0025] 1. When lightning strikes any position of the main current circuit, a lightning voltage will be formed on the main current circuit to the ground. If the lightning voltage is too high and causes the weak insulation link of the main current circuit to the ground to break down, a lightning current will be formed to discharge to the ground. Since the resistance of the main current circuit is very low, even if the lightning current partially passes through the main current circuit, the lightning current cannot form an overvoltage on the main current circuit and will not affect the normal operation of the main current circuit. If the lightning voltage is not enough to break down the weak insulation link of the main current circuit to the ground, no lightning current will be generated and the operation of the main current circuit will not be affected, thereby reducing the possibility of damage to electrical equipment caused by lightning strikes;

[0026] 2. When the current transmission and distribution lines are directly grounded or indirectly grounded, the lightning current will be introduced into the earth through the current transmission and distribution lines, directly or indirectly through voltage-sensitive devices. The loop resistance is very low, no high voltage or a small high voltage is generated, and the safety of the equipment and personnel around the equipment will not be endangered. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a circuit schematic diagram of a lightning protection power supply system in Example 1.

[0028] Figure 2 This is a circuit schematic diagram of a current distribution line grounding in a lightning protection power supply system in Example 2.

[0029] Figure numerals: 1. AC constant current source; 2. Current transmission and distribution line; 3. First terminal; 4. Second terminal; 5. Third terminal; 6. Fourth terminal; 7. Power conversion device. DETAILED DESCRIPTION

[0030] The following is combined with Figure 1-2 This application is described in further detail.

[0031] Lightning rods and lightning conductors can only provide certain protection against high-voltage transmission lines, towers or large regional buildings, and reduce the probability of lightning striking the area, but they cannot absolutely eliminate lightning strikes (i.e., there are still shielding lightning and induced lightning), nor can they prevent lightning from striking conductors outside the area and transmitting to the protected area. Since the current maximum lightning protection standard for low-voltage electrical equipment is 4kV, even the overvoltage caused by shielding lightning and induced lightning can reach tens of kV, so conventional solutions are basically ineffective.

[0032] The embodiment of the present application discloses a lightning protection power supply system.

[0033] Embodiment 1:

[0034] Reference Figure 1 The lightning protection power supply system includes an AC constant current source 1, a current main circuit and a plurality of power conversion devices 7; the input end of the AC constant current source 1 is connected to an AC voltage, the output end of the AC constant current source 1 is connected to the current main circuit, and provides AC current to the current main circuit; the current main circuit includes a plurality of anti-circuit breaking switches and a current transmission and distribution line 2 that connects the anti-circuit breaking switches in series.

[0035] Among them, in order to reduce the line impedance per unit length, the current transmission and distribution line 2 includes a multi-strand insulated wire with a small skin effect and a larger conductor cross-sectional area to reduce power supply loss. The current output from the output end of the AC constant current source 1 is an AC sinusoidal current with a preset frequency and a preset amplitude, wherein the preset amplitude is set according to needs and is not specifically limited. The frequency of the AC sinusoidal current is a base frequency or an intermediate frequency to improve the efficiency of power conversion. The base frequency is 50Hz or 60Hz, and the intermediate frequency is 50Hz-500Hz. The casing of the AC constant current source 1 and the casing of the power conversion device 7 are both grounded. In this embodiment, the grounding method of the casing of the AC constant current source 1 and the casing of the power conversion device 7 is direct grounding, so as to guide the current formed by lightning strikes on the casing of the AC constant current source 1 and the casing of the power conversion device 7 into the earth, thereby reducing the possibility of damage to the AC constant current source 1 and the power conversion device 7 caused by lightning strikes.

[0036] The anti-circuit-break switch includes a first terminal 3, a second terminal 4, a third terminal 5 and a fourth terminal 6; the first terminal 3 and the fourth terminal 6 are connected to the main current circuit; the second terminal 4 is connected to the first input end of the power conversion device 7, and the third terminal 5 is connected to the first output end of the power conversion device 7; when the first terminal 3 is connected to the second terminal 4, and the third terminal 5 is connected to the fourth terminal 6, the power conversion device 7 is connected to the main current circuit.

[0037] Among them, a low-voltage electrical device is also connected between the second input terminal and the second output terminal of the power conversion device 7.

[0038] In this embodiment, an AC constant current source 1 is installed in a power distribution station. The AC constant current source 1 is used to convert the voltage from the power grid or the generator into a constant AC current for external output. At this time, the first terminal 3 is connected to the second terminal 4, and the third terminal 5 is connected to the fourth terminal 6. The AC current enters the power conversion device 7 through the current transmission and distribution line 2. The power conversion device 7 converts the AC current into the power required by the low-voltage electrical equipment to power the low-voltage electrical equipment.

[0039] As an example, the power conversion device 7 can convert AC current into AC voltage, and can also convert into DC voltage.

[0040] When it is necessary to add low-voltage electrical equipment to the main current circuit or to remove low-voltage electrical equipment from the main current circuit, the first terminal 3 and the fourth terminal 6 of the anti-circuit-breaking switch corresponding to the low-voltage electrical equipment to be added or removed are connected to the main current circuit. At this time, the first terminal 3 and the fourth terminal 6 are connected, the connection between the first terminal 3 and the second terminal 4 is disconnected, and the connection between the third terminal 5 and the fourth terminal 6 is disconnected. At this time, the alternating current enters the main current circuit through the current transmission and distribution line 2, the first terminal 3 and the fourth terminal 6, and no longer enters the power conversion device 7 where the low-voltage electrical equipment needs to be added or removed. In this way, the normal transmission of current on the current transmission and distribution line 2 can be guaranteed without interruption during installation, removal, use or expansion.

[0041] After completing the operation of adding low-voltage electrical equipment or removing low-voltage electrical equipment, connect the first terminal 3 with the second terminal 4 in the anti-circuit-breaking switch corresponding to the added low-voltage electrical equipment or the removed low-voltage electrical equipment, connect the third terminal 5 with the fourth terminal 6, and then disconnect the connection between the first terminal 3 and the fourth terminal 6. At this time, the AC current enters the power conversion device through the current transmission and distribution line 2, the first terminal 3, and the second terminal 4 to supply power.

[0042] When lightning strikes any position of the main current loop, a lightning voltage will be formed on the main current loop to the ground. If the lightning voltage is too high and causes the weak insulation link of the main current loop to the ground to break down, a lightning current will be formed to discharge to the ground. Since the resistance of the main current loop formed by the AC constant current source 1, the current transmission and distribution line 2, the anti-circuit-breaking switch and the power conversion device 7 is very low, even if the lightning current partially passes through the main current loop, the lightning current cannot form an overvoltage on the main current loop and will not affect the normal operation of the main current loop. If the lightning voltage is not enough to break down the weak insulation link of the main current loop to the ground, no lightning current will be generated and the operation of the main current loop will not be affected, thereby achieving the purpose of continuous and stable power supply under lightning strike conditions.

[0043] When direct lightning strikes the casing of the power conversion device 7, since the casing of the power conversion device 7 does not belong to the main current circuit, the lightning strike will not affect the main current circuit, will not affect the continuous and stable operation of the power supply system under the lightning strike state, and will not affect the normal power supply of the power supply system. Since the casing of the power conversion device 7 is directly grounded, the lightning current will be directly introduced into the earth, so the residual voltage on the casing of the power conversion device 7 is extremely low, and will not endanger the safety of low-voltage electrical equipment.

[0044] When lightning strikes in the surrounding area and generates induced current on conductors such as the current transmission and distribution lines 2 and the circuit breaker, the induced current may form a high voltage to the ground on the current transmission lines, the circuit breaker and the power conversion device 7, which may be dangerous for people to touch. However, the working circuits in the power supply system are not affected, and the purpose of continuous and stable power supply under lightning strike can still be achieved.

[0045] Generally, the AC constant current source 1 is installed indoors, and the lightning strike will not directly act on the AC constant current source 1. If the AC constant current source 1 is installed outdoors, when the lightning strike acts on the shell of the AC constant current source 1, because the shell of the AC constant current source 1 belongs to a non-current main circuit, the lightning strike will not affect the current main circuit, will not affect the continuous and stable operation of the power supply system under the lightning strike state, and will not affect the normal power supply of the power supply system. Because the AC constant current source 1 is directly grounded, the lightning current will be directly introduced into the earth, and the residual voltage on the shell of the AC constant current source 1 is extremely low, and will not endanger the safety of low-voltage electrical equipment and personnel.

[0046] Embodiment 2:

[0047] Reference Figure 2 The difference from Example 1 is that the current transmission and distribution line 2 is grounded. The current transmission and distribution line 2 can be directly grounded or indirectly grounded. When indirect grounding is adopted, the indirect grounding is performed through a voltage-sensitive device. The voltage-sensitive device includes a varistor, an overvoltage protector and a discharge tube.

[0048] When direct lightning strikes any position of the current transmission line, the anti-circuit-break switch and the power conversion device 7, the lightning current will be introduced into the earth through the current transmission and distribution line 2, directly or indirectly through voltage-sensitive devices. Since the resistance of the main current loop is very low, no high voltage or a relatively small high voltage is generated, and the safety of the equipment and personnel around the equipment will not be endangered.

[0049] When lightning strikes in the surrounding area induce lightning current on conductors such as current transmission lines and circuit breaker switches, the induced lightning current is transmitted with low resistance and is indirectly introduced into the earth through direct or voltage-sensitive devices. No high voltage is generated in the live parts, and the residual voltage at the grounding point has no effect on the power transmission circuit of the entire system, will not affect the normal power supply of the load, and will not endanger the safety of the equipment.

[0050] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A lightning protection power supply system, characterized in that: include: AC constant current source, current main circuit and several power conversion devices; The input end of the AC constant current source is connected to an AC voltage, and the output end of the AC constant current source is connected to the current main loop to provide an AC current to the current main loop; The main current circuit includes a plurality of anti-breaking switches and current transmission and distribution lines connecting the anti-breaking switches in series; The anti-circuit-break switch comprises a first terminal, a second terminal, a third terminal and a fourth terminal; the first terminal and the fourth terminal are connected to the main current circuit; The second terminal is connected to the first input terminal of the power conversion device, and the third terminal is connected to the first output terminal of the power conversion device; when the first terminal is connected to the second terminal, and the third terminal is connected to the fourth terminal, the power conversion device is connected to the current main circuit; An AC or DC voltage is output between the second input terminal and the second output terminal of the power conversion device.

2. A lightning protection power supply system according to claim 1, characterized in that: The current outputted from the output end of the AC constant current source is an AC sinusoidal current with a preset frequency and a preset amplitude.

3. A lightning protection power supply system according to claim 1, characterized in that: The frequency of the AC sinusoidal current is a base frequency or an intermediate frequency, the base frequency is 50 Hz or 60 Hz, and the intermediate frequency is 50 Hz-500 Hz.

4. A lightning protection power supply system according to claim 1, characterized in that: The shell of the power conversion device is grounded.

5. The lightning protection power supply system according to claim 1, characterized in that: The shell of the AC constant current source is grounded.

6. A lightning protection power supply system according to claim 1, characterized in that: The current transmission and distribution line is directly grounded.

7. A lightning protection power supply system according to claim 1, characterized in that: The current transmission and distribution line is indirectly grounded.

8. The lightning protection power supply system according to claim 1, characterized in that: A low-voltage electrical device is connected between the second input terminal and the second output terminal of the power conversion device.

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