A circuit switching control device, short circuit fault protection device and method

Abstract

The application belongs to the technical field of short-circuit protection, and provides a loop switching control device, a short-circuit fault protection device and a method. The loop switching control device comprises a loop switching driving wheel and a loop switching driven wheel, both of which are in a fan-shaped structure; the loop switching driving wheel and the loop switching driven wheel can rotate around their respective rotation axes, and the two are mutually meshed; one side of the loop switching driving wheel is provided with a first loop contact point, and a second loop contact point is further provided along an arc trajectory line of the loop switching driving wheel, and the second loop contact point can be in contact with the first loop contact point; one side of the loop switching driven wheel is provided with a third loop contact point, and a fourth loop contact point is further provided along an arc trajectory line of the loop switching driven wheel, and the fourth loop contact point can be in contact with the third loop contact point; the loop switching driving wheel and the loop switching driven wheel are further connected with their respective elastic structures; the elastic structures drive the loop switching driving wheel and the loop switching driven wheel to return to the original position.

Description

Technical Field

[0001] This invention belongs to the field of short-circuit protection technology, and particularly relates to a circuit switching control device, a short-circuit fault protection device and method. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] For photovoltaic power plants using string inverters, the positive and negative cables of each string circuit of the MPPT (Maximum Power Point Tracking) are connected via MC4 connectors (photovoltaic connectors) and laid along the path to the inverter, also connected to the string circuit of the inverter's MPPT via MC4 connectors. With technological advancements, string inverters have increasingly larger capacities and support more circuits. During the construction of ground-mounted photovoltaic power plants, the DC cables of the string circuits are typically laid inside the purlins of the photovoltaic module support. These purlins are mostly made of galvanized metal, and defects such as burrs inevitably occur during their production, easily damaging the DC cables. Combined with potentially improper installation, this can easily cause damage to the DC cables and consequently, compromise the insulation. Although most inverters have circuit insulation impedance detection and alarm functions, the long routing makes troubleshooting difficult, leading to increasingly severe insulation aging over time, potentially causing inter-electrode short circuits at some point; or short circuits may occur shortly after a low insulation impedance alarm is triggered. The short-circuit current of photovoltaic modules can create an arc that cannot be extinguished at the short-circuit point, causing the fire to spread, affecting other circuits, and even burning out the inverter.

[0004] The inventors discovered that there is currently a lack of circuit switching control devices and short-circuit fault protection devices that can quickly cut off the fault current when an inter-pole short circuit occurs in the cable circuit from the component to the inverter. Summary of the Invention

[0005] To address the technical problems existing in the background art, the present invention provides a loop switching control device, a short-circuit fault protection device and method, which can achieve the purpose of quickly cutting off the fault current when an inter-pole short circuit occurs in the cable circuit from the component to the inverter through the combined application of the functional loop switching control device, the energy storage device and the energy release control device.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The first aspect of the present invention provides a loop switching control device.

[0008] A loop switching control device includes: a loop switching driving wheel and a loop switching driven wheel; both the loop switching driving wheel and the loop switching driven wheel have a fan-shaped structure; both the loop switching driving wheel and the loop switching driven wheel can rotate around their respective axes, and the two mesh with each other;

[0009] A first circuit contact is provided on one side of the circuit switching drive wheel, and a second circuit contact is also provided along the arc-shaped trajectory line of the rotation of the circuit switching drive wheel. The second circuit contact can contact the first circuit contact.

[0010] A third circuit contact is provided on one side of the circuit switching driven wheel, and a fourth circuit contact is also provided along the arc-shaped trajectory line of the rotation of the circuit switching driven wheel. The fourth circuit contact can contact the third circuit contact.

[0011] The arc distance between the fourth circuit contact and the third circuit contact is less than the arc distance between the second circuit contact and the first circuit contact;

[0012] The loop switching drive wheel and the loop switching driven wheel are also connected to their respective elastic structures; the elastic structures are used to drive the loop switching drive wheel and the loop switching driven wheel back to their original positions.

[0013] In one implementation, under the control of external force, the circuit switching drive wheel can rotate towards the second circuit contact, thereby driving the circuit switching drive wheel to rotate, first making the fourth circuit contact contact with the third circuit contact, and then making the second circuit contact contact with the first circuit contact.

[0014] In one implementation, when the external force control disappears, the elastic structure is used to drive the circuit switching drive wheel to rotate toward the initial position, first disconnecting the second circuit contact from the first circuit contact, and then disconnecting the fourth circuit contact from the third circuit contact.

[0015] As one implementation, the elastic structure connected to the circuit switching drive wheel includes:

[0016] The first elastic element and the second elastic element are respectively connected to the two sides of the circuit switching drive wheel.

[0017] As one implementation, the elastic structure connected to the circuit switching driven wheel includes:

[0018] The third elastic element is connected to one side of the circuit switching drive wheel, which is the side where the third circuit contact is located.

[0019] In one implementation, the first circuit contact, the second circuit contact, the third circuit contact, and the fourth circuit contact are all magnetic structures.

[0020] A second aspect of the present invention provides a control method for the loop switching control device as described above.

[0021] A control method for the loop switching control device as described above, comprising:

[0022] Under the control of external force, the control circuit switching drive wheel rotates towards the second circuit contact, thereby driving the circuit switching drive wheel to rotate so that the fourth circuit contact and the third circuit contact make contact first, and the second circuit contact and the first circuit contact make contact later.

[0023] When the external force control disappears, the elastic structure drives the circuit switching drive wheel to rotate toward the initial position, so that the second circuit contact disconnects from the first circuit contact first, and the fourth circuit contact disconnects from the third circuit contact later.

[0024] A third aspect of the present invention provides a short-circuit fault protection device.

[0025] A short-circuit fault protection device, which is connected to the positive and negative terminals of the photovoltaic module string and the DC cable of the circuit through a conversion connector;

[0026] The short-circuit fault protection device includes:

[0027] Energy release control device circuit and energy release circuit;

[0028] The on / off state of the energy release control device circuit and the energy release circuit is controlled by the circuit switching control device as described above.

[0029] As one implementation, the short-circuit fault protection device is also provided with a maintenance circuit, and a maintenance switch is connected in series in the maintenance circuit; when maintaining the protection device, the energy of the energy storage device is released by first removing the energy release control device and then closing the maintenance switch.

[0030] A fourth aspect of the present invention provides a method for operating the short-circuit fault protection device as described above.

[0031] A method for operating a short-circuit fault protection device as described above includes:

[0032] When the photovoltaic module is generating electricity normally, the loop current drives the functional loop switching control device through the coil magnetic field, so that it first connects the energy release control device loop and then connects the energy release loop to ensure the safe connection of the loop.

[0033] When the machine is not powered on, there is no current in the circuit. The circuit switching control device returns to its original position under the action of the elastic structure. It first disconnects the energy release circuit and then disconnects the energy release control device circuit.

[0034] In the event of a short circuit fault, the energy release control device connects the energy release circuit, instantly discharging energy to the fuse to melt it and cut off the fault current.

[0035] The beneficial effects of this invention are:

[0036] (1) This invention achieves the following by switching the loop current control function loop: when the generator is running normally, the energy storage device is in a charging state and the energy release control device is in an inter-electrode voltage monitoring state; when the generator is shut down normally or when it fails to start due to lack of sunlight, the energy release control device exits voltage monitoring and the energy storage device is in an energy storage state; in the event of a short circuit fault, the energy storage device and the energy release control device quickly release energy to the fuse, causing it to melt quickly and cut off the fault current; when the protection device is under maintenance, the energy of the energy storage device is released through the maintenance switch to ensure safety.

[0037] (2) Since the components and DC cables are connected through this device, its protection range is the entire length of the string circuit DC cable. When a short circuit fault occurs, the fault current in the circuit will be quickly cut off to prevent fire and the spread of fire, thereby avoiding greater losses. This invention protects the string circuit and inverter, reduces the loss of components and power generation, and reduces maintenance time and financial costs.

[0038] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0039] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0040] Figure 1 This is a schematic diagram of the loop switching control device according to an embodiment of the present invention.

[0041] Figure 2 This is a schematic diagram of a short-circuit protection device for photovoltaic string circuits according to an embodiment of the present invention.

[0042] Among them, 1: coil; 2: fuse; 3: circuit switching control device; 4: current limiting resistor; 5: energy release control device; 6: diode; 7: energy storage device; 8: maintenance switch; 9: auxiliary contact of energy release control device;

[0043] 3-1: Terminal; 3-2: Circuit switching driven wheel; 3-3: Circuit switching driving wheel; 3-4: Circuit contact; 3-5: Spring. Detailed Implementation

[0044] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0045] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0046] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0047] <Circuit Switching Control Device>

[0048] like Figure 1 As shown, this embodiment provides a loop switching control device 3, which has four terminals 3-1 for connecting to the four ends of two series-connected loops. The loop switching control device 3 includes a loop switching driving wheel 3-3 and a loop switching driven wheel 3-2; both the loop switching driving wheel 3-3 and the loop switching driven wheel 3-2 have a fan-shaped structure; both the loop switching driving wheel 3-3 and the loop switching driven wheel 3-2 can rotate around their respective axes, and the two mesh with each other.

[0049] It should be noted that the sector size of the circuit switching driving wheel 3-3 and the circuit switching driven wheel 3-2 can be specifically set by those skilled in the art according to the actual situation.

[0050] The loop switching control device 3 also includes a loop contact 3-4. Specifically, a first loop contact is provided on one side of the loop switching drive wheel 3-3, and a second loop contact is provided along the arc-shaped trajectory line of the rotation of the loop switching drive wheel 3-3. The second loop contact can contact the first loop contact.

[0051] A third circuit contact is provided on one side of the circuit switching driven wheel 3-2, and a fourth circuit contact is also provided along the arc-shaped trajectory line of the rotation of the circuit switching driven wheel. The fourth circuit contact can contact the third circuit contact.

[0052] The arc distance between the fourth circuit contact and the third circuit contact is less than the arc distance between the second circuit contact and the first circuit contact.

[0053] In one or more embodiments, the first circuit contact, the second circuit contact, the third circuit contact, and the fourth circuit contact are all magnetic structures. This allows the circuit switching drive wheel and the circuit switching driven wheel to rotate under external force control.

[0054] In this embodiment, the loop switching drive wheel 3-3 and the loop switching driven wheel 3-2 are also connected to their respective corresponding elastic structures; the elastic structures are used to drive the loop switching drive wheel and the loop switching driven wheel back to their original positions.

[0055] The elastic structure connected to the circuit switching drive wheel includes:

[0056] The first elastic element and the second elastic element are respectively connected to the two sides of the circuit switching drive wheel.

[0057] The elastic structure connected to the circuit switching driven wheel includes:

[0058] The third elastic element is connected to one side of the circuit switching drive wheel, which is the side where the third circuit contact is located.

[0059] In this embodiment, the first elastic element, the second elastic element, and the third elastic element are all implemented using springs 3-5.

[0060] It is understood that in other embodiments, those skilled in the art can also use existing elastic structures that are elastic and can return to their original position to implement the first elastic element, the second elastic element, and the third elastic element, which will not be elaborated here.

[0061] In the specific implementation process, under the control of external force (such as magnetic force), the circuit switching drive wheel can rotate towards the second circuit contact, thereby driving the circuit switching drive wheel to rotate, first making the fourth circuit contact contact with the third circuit contact, and then making the second circuit contact contact with the first circuit contact.

[0062] When the external force (such as magnetic force) control disappears, the elastic structure is used to drive the circuit switching drive wheel to rotate toward the initial position, first disconnecting the second circuit contact from the first circuit contact, and then disconnecting the fourth circuit contact from the third circuit contact.

[0063] It should be noted that in other embodiments, the external force for switching the control loop to the drive wheel can also be human force or other forms of external force, which will not affect the structure and working principle of the loop switching control. The specific form of external force can be selected by those skilled in the art according to the actual situation, and will not be elaborated here.

[0064] <Control Method of Loop Switching Control Device>

[0065] The control method of the loop switching control device described above includes:

[0066] Step 1: Under the control of external force, the control circuit switching drive wheel rotates towards the second circuit contact, thereby driving the circuit switching drive wheel to rotate so that the fourth circuit contact and the third circuit contact make contact first, and the second circuit contact and the first circuit contact make contact later.

[0067] Step 2: When the external force control disappears, the elastic structure drives the circuit switching drive wheel to rotate toward the initial position, so that the second circuit contact disconnects from the first circuit contact first, and the fourth circuit contact disconnects from the third circuit contact later.

[0068] Short-circuit fault protection device

[0069] like Figure 2 As shown, a short-circuit fault protection device is provided, which is connected to the positive and negative terminals of the photovoltaic module string and the DC cable of the circuit through a conversion connector (such as an MC4 connector).

[0070] The short-circuit fault protection device includes:

[0071] Energy release control device circuit and energy release circuit;

[0072] The on / off state of the energy release control device circuit and the energy release circuit is controlled by the circuit switching control device 3 as described above.

[0073] according to Figure 2 As can be seen, the energy release control device circuit of this embodiment has a coil 1, a current-limiting resistor 4, an energy release control device 5 and a fuse 2 connected in series.

[0074] In this embodiment, a current-limiting resistor 4 and a fuse 2 are connected in series in the energy release circuit.

[0075] The short-circuit fault protection device in this embodiment also includes an energy storage circuit, in which a diode 6, an energy storage device 7 (such as a capacitor), a fuse 2, and a coil 1 are connected in series. Reference numeral 9 indicates an auxiliary contact of the energy release control device 5.

[0076] Coil 1 is used to generate a magnetic field when the circuit is switched on or off, so as to control the circuit switching drive wheel inside the circuit switching control device. Under the control of magnetic force, it rotates towards the second circuit contact, thereby driving the circuit switching drive wheel to rotate.

[0077] exist Figure 2 In the short-circuit fault protection device, a maintenance circuit is also provided, and a maintenance switch 8 is connected in series in the maintenance circuit; when maintaining the protection device, the energy of the energy storage device is released by first removing the energy release control device 5 and then closing the maintenance switch 8.

[0078] Specifically, the energy release control device 5 using a relay will be used as an example to illustrate this in detail. Figure 2The operating logic of the short-circuit fault protection device in the system is as follows:

[0079] Before the circuit in the short-circuit fault protection device is activated, there is current in the circuit.

[0080] During normal power generation, contact a is closed first, the relay is activated, and its normally closed auxiliary contacts c and d are disconnected, disconnecting the energy storage release circuit to ensure that the energy storage release circuit does not discharge under normal conditions; its normally open contact e is closed, and the energy storage capacitor 7 is in a charging state; then contact b is closed to ensure the smooth operation of the energy storage circuit in the event of a short circuit between the poles of the line.

[0081] When a short circuit occurs, the normally closed contacts c and d of the relay close, and the energy storage capacitor 7 discharges through contacts b, c and d to fuse 2, causing it to melt.

[0082] When the radiation level is insufficient to start the inverter due to weather conditions, the inverter will automatically shut down, there will be no current in the circuit, contact b will open first, cutting off the energy storage release circuit; then the relay will lose power, normally closed auxiliary contacts c and d will close, normally open contact e will open, and the energy storage capacitor 7 will no longer be charged.

[0083] When maintenance is required, disconnect the energy release control device 5 from the circuit, then close the maintenance switch 8 to discharge the capacitor. Only after it is safe to do so should the device be maintained.

[0084] In this embodiment, the positive and negative terminals of the photovoltaic module string and the DC cable of the circuit are connected to the four wires reserved at both ends of the device using MC4 connectors. During normal power generation, the circuit current drives the functional circuit switching control device through the coil magnetic field, causing it to first connect the energy release control device circuit and then the energy release circuit, ensuring safe circuit connection. In the event of normal shutdown or other conditions that prevent the device from starting due to lack of sunlight, there is no current in the circuit. The functional circuit switching control device returns to its original position under the action of spring force, and its disconnection sequence is to first disconnect the energy release circuit and then disconnect the energy release control circuit. In the event of a short circuit fault, since the inter-electrode voltage is close to zero, the energy release control device connects the energy release circuit, instantly discharging to the fuse to melt it and cut off the fault current.

[0085] <Operating Method of Short Circuit Fault Protection Device>

[0086] The operating method of the short-circuit fault protection device described in this embodiment includes:

[0087] When the photovoltaic module is generating electricity normally, the loop current drives the functional loop switching control device through the coil magnetic field, so that it first connects the energy release control device loop and then connects the energy release loop to ensure the safe connection of the loop.

[0088] When the machine is not powered on, there is no current in the circuit. The circuit switching control device returns to its original position under the action of the elastic structure. It first disconnects the energy release circuit and then disconnects the energy release control device circuit.

[0089] In the event of a short circuit fault, the energy release control device connects the energy release circuit, instantly discharging energy to the fuse to melt it and cut off the fault current.

[0090] When overhauling the protection device, the energy of the energy storage device is released by closing the maintenance switch, which ensures safety.

[0091] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A short-circuit fault protection device, characterized in that, The short-circuit fault protection device is connected to the positive and negative terminals of the photovoltaic module string and the DC cable of the circuit through a conversion connector. The short-circuit fault protection device includes: an energy release control device circuit and an energy release circuit; The on / off state of the energy release control device circuit and the energy release circuit is controlled by the circuit switching control device, which includes: a circuit switching driving wheel and a circuit switching driven wheel; both the circuit switching driving wheel and the circuit switching driven wheel are fan-shaped structures; both the circuit switching driving wheel and the circuit switching driven wheel can rotate around their respective axes, and the two mesh with each other; A first circuit contact is provided on one side of the circuit switching drive wheel, and a second circuit contact is also provided along the arc-shaped trajectory line of the rotation of the circuit switching drive wheel. The second circuit contact can contact the first circuit contact. A third circuit contact is provided on one side of the circuit switching driven wheel, and a fourth circuit contact is also provided along the arc-shaped trajectory line of the rotation of the circuit switching driven wheel. The fourth circuit contact can contact the third circuit contact. The arc distance between the fourth circuit contact and the third circuit contact is less than the arc distance between the second circuit contact and the first circuit contact; The loop switching drive wheel and the loop switching driven wheel are also connected to their respective elastic structures; the elastic structures are used to drive the loop switching drive wheel and the loop switching driven wheel back to their original positions; When the external force control disappears, the elastic structure is used to drive the circuit switching drive wheel to rotate toward the initial position, first disconnecting the second circuit contact from the first circuit contact, and then disconnecting the fourth circuit contact from the third circuit contact. The short-circuit fault protection device is also equipped with a maintenance circuit, and a maintenance switch is connected in series in the maintenance circuit. When maintaining the protection device, the energy of the energy storage device is released by first removing the energy release control device and then closing the maintenance switch.

2. A short-circuit fault protection device as described in claim 1, characterized in that, Under the control of external force, the circuit switching drive wheel can rotate towards the second circuit contact, thereby driving the circuit switching drive wheel to rotate, first making the fourth circuit contact contact with the third circuit contact, and then making the second circuit contact contact with the first circuit contact.

3. A short-circuit fault protection device as described in claim 1, characterized in that, The elastic structure connected to the circuit switching drive wheel includes: The first elastic element and the second elastic element are respectively connected to the two sides of the circuit switching drive wheel.

4. A short-circuit fault protection device as described in claim 1, characterized in that, The elastic structure connected to the circuit switching driven wheel includes: The third elastic element is connected to one side of the circuit switching drive wheel, which is the side where the third circuit contact is located.

5. A short-circuit fault protection device as described in claim 1, characterized in that, The first circuit contact, the second circuit contact, the third circuit contact, and the fourth circuit contact are all magnetic structures.

6. A control method for a loop switching control device as described in any one of claims 1-5, characterized in that, include: Under the control of external force, the control circuit switching drive wheel rotates towards the second circuit contact, thereby driving the circuit switching drive wheel to rotate so that the fourth circuit contact and the third circuit contact make contact first, and the second circuit contact and the first circuit contact make contact later. When the external force control disappears, the elastic structure drives the circuit switching drive wheel to rotate toward the initial position, so that the second circuit contact disconnects from the first circuit contact first, and the fourth circuit contact disconnects from the third circuit contact later.

7. The operating method of the short-circuit fault protection device as described in any one of claims 1-5, characterized in that, include: When the photovoltaic module is generating electricity normally, the circuit current drives the circuit switching control device through the coil magnetic field, so that it first connects the energy release control device circuit and then connects the energy release circuit to ensure the safe connection of the circuit. When the machine is not powered on, there is no current in the circuit. The circuit switching control device returns to its original position under the action of the elastic structure. It first disconnects the energy release circuit and then disconnects the energy release control device circuit. In the event of a short circuit fault, the energy release control device connects the energy release circuit, instantly discharging energy to the fuse to melt it and cut off the fault current.

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