Photovoltaic system, photovoltaic storage system, photovoltaic string, and circuit breaker and control method thereof

Abstract

The present application provides a photovoltaic system, a photovoltaic storage system, a photovoltaic string, a circuit breaker and a control method thereof. When current backflow occurs between photovoltaic strings, since the circuit breaker in the photovoltaic string with low string voltage will turn off the main switch module, the control method will reduce the output side voltage of the circuit breaker in the photovoltaic string with low string voltage to below the preset voltage value by controlling the conduction of the auxiliary switch module; and since the photovoltaic string with high string voltage is connected in parallel with the photovoltaic string with low string voltage, the control method will also reduce the output side voltage of the circuit breaker in the photovoltaic string with high string voltage to below the preset voltage value; in addition, since the preset voltage value is the threshold voltage of the circuit breaker shutdown protection, the circuit breaker in the photovoltaic string with high string voltage will enter shutdown protection, so the control method can prevent current backflow between photovoltaic strings with circuit breakers on the DC side of the inverter system.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to a photovoltaic system, a photovoltaic storage system, a photovoltaic string, a circuit breaker and a control method thereof. Background Art

[0002] exist Figure 1 In the photovoltaic grid-connected system shown, multiple photovoltaic modules 01 are cascaded to form a photovoltaic string 02, and multiple photovoltaic strings 02 are connected to the DC side of the inverter system 03. In actual applications, due to reasons such as light shielding, aging of the components themselves, or different numbers of components, the string voltages of the photovoltaic strings 02 are not completely the same. When the inverter system 03 is shut down, if the string voltages of the photovoltaic strings 02 are not completely the same, the photovoltaic string 02 with a high string voltage will flow back to the string with a low string voltage, such as Figure 1 As shown by the dotted line in .

[0003] like Figure 2 As shown, even if Figure 1 A circuit breaker 04 is added to each photovoltaic module 01. Since the backflow current can keep the output voltage and current of the circuit breaker 04 in the string with a high string voltage stable, the circuit breaker 04 in the string with a high string voltage still cannot be turned off, thereby failing to cut off the current backflow loop.

[0004] Therefore, how to prevent the current backflow between the photovoltaic strings with circuit breakers on the DC side of the inverter system is a technical problem that needs to be solved urgently. Summary of the invention

[0005] In view of this, the present invention provides a photovoltaic system, a photovoltaic storage system, a photovoltaic string, a circuit breaker and a control method thereof to prevent current backflow between photovoltaic strings with circuit breakers on the DC side of an inverter system.

[0006] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0007] In a first aspect, the present application provides a method for controlling a circuit breaker, wherein an auxiliary switch module is added between two poles on an output side of the circuit breaker; the method for controlling the circuit breaker comprises:

[0008] Determining whether the main switch module in the circuit breaker is turned off;

[0009] If the main switch module is turned off, the output side voltage of the circuit breaker is reduced to below a preset voltage value by controlling the auxiliary switch module to be turned on; the preset voltage value is the threshold voltage of the circuit breaker shutdown protection.

[0010] Optionally, determining whether a main switch module in the circuit breaker is turned off includes:

[0011] Determining whether the output side current of the circuit breaker is less than a preset current value;

[0012] If the output side current of the circuit breaker is less than the preset current value, it is determined that the main switch module is turned off.

[0013] Optionally, controlling the auxiliary switch module to reduce the output side voltage of the circuit breaker to below a preset voltage value includes:

[0014] The auxiliary switch module is controlled to be turned on.

[0015] Optionally, controlling the auxiliary switch module to reduce the output side voltage of the circuit breaker to below a preset voltage value includes:

[0016] Controlling the auxiliary switch module to be turned on and off periodically;

[0017] In one cycle, the ratio of the on-time to the off-time of the auxiliary switch module is greater than a preset proportion, and the preset proportion is the ratio of the on-time to the off-time when the output side voltage of the circuit breaker is equal to the preset voltage value.

[0018] A second aspect of the present application provides a circuit breaker, comprising: a main switch module, a first controller and at least one auxiliary switch module; wherein:

[0019] The negative electrode on the input side of the circuit breaker is connected to the negative electrode on the output side of the circuit breaker;

[0020] The main switch module is arranged between the positive pole at the input side of the circuit breaker and the positive pole at the output side of the circuit breaker, and the control end of the main switch module is connected to the corresponding output end of the first controller;

[0021] Each of the auxiliary switch modules is disposed between the positive electrode at the output side of the circuit breaker and the negative electrode at the output side of the circuit breaker, and each of the auxiliary switch modules is connected to the output end of the first controller;

[0022] The first controller is used to execute the control method of the circuit breaker as described in any one of the first aspects of the present application.

[0023] Optionally, it also includes: a reverse cutoff module, an output current detection module, an input side voltage detection module and an output side voltage detection module

[0024] The positive electrode of the reverse cutoff module is connected to the negative electrode of the output side of the circuit breaker, and the negative electrode of the reverse cutoff module is connected to the positive electrode of the output side of the circuit breaker;

[0025] The current detection module, the input side voltage detection module and the output side voltage detection module are respectively communicatively connected to the corresponding communication ends of the first controller; the sampling end of the current detection module is used to detect the output side current of the circuit breaker, the input side voltage detection module is used to detect the input side voltage of the circuit breaker, and the output side voltage detection module is used to detect the output side voltage of the circuit breaker.

[0026] Optionally, the auxiliary switch module includes: a switch tube.

[0027] The third aspect of the present application provides a photovoltaic string, comprising: N photovoltaic modules and N circuit breakers; N is an integer greater than 1; wherein:

[0028] The switch is a switch as described in any one of the second aspects of the present application;

[0029] The connection ends of the photovoltaic modules are connected to the input sides of the circuit breakers in a one-to-one correspondence;

[0030] The two poles at the output side of each of the circuit breakers are cascaded to the two poles at the connection end of the photovoltaic string.

[0031] A fourth aspect of the present application provides a photovoltaic string, comprising: a circuit breaker and at least two photovoltaic modules; wherein:

[0032] The switch is a switch as described in any one of the second aspects of the present application;

[0033] The two poles of the connection end of each photovoltaic module are cascaded to the two poles of the input side of the circuit breaker;

[0034] The output side of the circuit breaker serves as a connection end of the photovoltaic string.

[0035] A fifth aspect of the present application provides a photovoltaic system, comprising: a first inverter system, a first system controller and at least two photovoltaic strings; wherein:

[0036] The connection ends of the photovoltaic strings are respectively connected to the DC side of the first inverter system, and the AC side of the first inverter system serves as the AC side of the photovoltaic system;

[0037] The photovoltaic string is the photovoltaic string as described in the third aspect or the fourth aspect of the present application;

[0038] The first system controller is respectively connected to the controllers in the circuit breakers in the photovoltaic strings and the first inverter system for communication.

[0039] Optionally, the first inverter system includes: a first inverter circuit, a first DC conversion circuit and a second controller; wherein:

[0040] The first side of the first DC conversion circuit serves as the DC side of the first inverter system, the second side of the first DC conversion circuit is connected to the DC side of the first inverter circuit, and the AC side of the first inverter circuit serves as the AC side of the first inverter system;

[0041] The output terminals of the second controller are respectively connected to the control terminals of the first DC conversion circuit and the control terminals of the first inverter circuit; the communication terminal of the second controller is communicatively connected to the communication terminal of the first system controller.

[0042] Optionally, the first system controller and the second controller are integrated together.

[0043] A sixth aspect of the present application provides a photovoltaic storage system, comprising: a second inverter system, an energy storage system, a second system controller, and at least two photovoltaic strings; wherein:

[0044] The connection ends of the photovoltaic strings are respectively connected to the DC side of the second inverter system, and the AC side of the second inverter system serves as the AC side of the photovoltaic system;

[0045] The connection port of the energy storage system is connected to the DC side of the second inverter system;

[0046] The photovoltaic string is the photovoltaic string as described in the third aspect or the fourth aspect of the present application;

[0047] The second system controller is respectively connected to the controllers in the circuit breakers in the photovoltaic strings and the second inverter system for communication.

[0048] It can be seen from the above technical solution that the present invention provides a control method for a circuit breaker, wherein the circuit breaker includes a main switch module, and an auxiliary switch module is additionally provided between two poles on the output side of the circuit breaker. When current backflow occurs between photovoltaic strings, since the circuit breaker in the photovoltaic string with low string voltage will turn off the main switch module, the control method will reduce the output side voltage of the circuit breaker in the photovoltaic string with low string voltage to below the preset voltage value by controlling the auxiliary switch module to turn on; and since the photovoltaic string with high string voltage is connected in parallel with the photovoltaic string with low string voltage, the control method will also reduce the output side voltage of the circuit breaker in the photovoltaic string with high string voltage to below the preset voltage value; in addition, since the preset voltage value is the threshold voltage of the circuit breaker shutdown protection, that is, when the output side voltage of the circuit breaker is less than the preset voltage, the circuit breaker enters shutdown protection, so the circuit breaker in the photovoltaic string with high string voltage will enter shutdown protection, that is, the current backflow loop is cut off, so the control method of the circuit breaker provided in the present application can prevent current backflow between photovoltaic strings with circuit breakers on the DC side of the inverter system. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0050] Figure 1 and Figure 2 They are respectively structural schematic diagrams of two photovoltaic grid-connected systems in the prior art;

[0051] Figure 3-Figure 6 Flow charts of four implementation methods of the control method of the circuit breaker provided in the embodiments of the present application;

[0052] Figure 7 and Figure 8 They are schematic diagrams of the structures of two implementation modes of the circuit breaker provided in the embodiments of the present application;

[0053] Fig. 9 and Fig.10 The schematic diagrams of the structures of two implementation modes of photovoltaic strings provided in the embodiments of the present application are shown respectively;

[0054] Fig.11 A schematic diagram of the structure of a photovoltaic system provided in an embodiment of the present application;

[0055] Fig.12 A schematic diagram of the structure of a first inverter system provided in an embodiment of the present application;

[0056] Fig.13 A schematic diagram of the structure of the optical storage system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0057] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0058] In this application, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0059] In order to prevent current backflow between photovoltaic strings with circuit breakers on the DC side of an inverter system, an embodiment of the present application provides a control method for a circuit breaker, wherein the circuit breaker includes a main switch module and an auxiliary switch module is added between the two poles on the output side of the circuit breaker.

[0060] The specific process of the control method of the shutdown device is as follows Figure 3 As shown, the specific steps include:

[0061] S110: Determine whether the main switch module in the circuit breaker is turned off.

[0062] If the main switch module is turned off, step S120 is executed; if the main switch module is not turned off, the process returns to step S110.

[0063] When the main switch module is turned off, the output side of the circuit breaker is switched to the transmission channel of the output side, that is, the circuit breaker is in the off state.

[0064] In practical applications, a specific process of a specific implementation of step S110 is as follows: Figure 4 As shown, the specific steps include:

[0065] S210: Determine whether the output side current of the circuit breaker is less than a preset current value.

[0066] If the output side current of the circuit breaker is less than the preset current value, step S220 is executed; if the output side current of the circuit breaker is greater than or equal to the preset current value, step S230 is executed;

[0067] In practical applications, the circuit breaker detects the current on its own output side and shuts itself down when the current on its own output side is less than a certain value. Therefore, it is possible to determine whether to perform a shutdown operation by judging the current on the output side of the circuit breaker.

[0068] Among them, the preset current value is the critical current value of the output side current of the circuit breaker itself when performing a shutdown operation; it can be set according to actual conditions, and is not specifically limited here, and is within the protection scope of this application.

[0069] S220: Determine whether the main switch module is turned off.

[0070] S230: Determine whether the main switch module is not turned off.

[0071] The above is only one implementation of step S110, which is not limited to this in practical applications and is not specifically limited here. It can be determined according to specific circumstances and is within the protection scope of this application.

[0072] S120, reducing the output side voltage of the circuit breaker to below a preset voltage value by controlling the auxiliary switch module to be turned on.

[0073] The preset voltage value is the threshold voltage of the shutdown protection of the circuit breaker, that is, when the output side voltage of the circuit breaker drops below the preset voltage value, the circuit breaker enters the shutdown protection.

[0074] It should be noted that when the output side voltage of the circuit breaker drops below a preset voltage value, the circuit breaker may enter undervoltage shutdown protection or reset shutdown protection, and the specific situation is determined by the reduced output side voltage.

[0075] When current backflow occurs between photovoltaic strings, since the circuit breaker in the photovoltaic string with low string voltage will turn off the main switch module, the control method will reduce the output side voltage of the circuit breaker in the photovoltaic string with low string voltage to below the preset voltage value by controlling the auxiliary switch module to turn on; and since the photovoltaic string with high string voltage is connected in parallel with the photovoltaic string with low string voltage, the control method will also reduce the output side voltage of the circuit breaker in the photovoltaic string with high string voltage to below the preset voltage value; in addition, since the preset voltage value is the threshold voltage of the circuit breaker shutdown protection, that is, when the output side voltage of the circuit breaker is less than the preset voltage, the circuit breaker enters shutdown protection, so the circuit breaker in the photovoltaic string with high string voltage will enter shutdown protection, that is, the current backflow loop is cut off, so the control method of the circuit breaker provided in the present application can prevent current backflow between photovoltaic strings with circuit breakers on the DC side of the inverter system.

[0076] Another embodiment of the present application provides two implementations of step S120. The specific process of the first implementation is as follows: Figure 5 (Only in Figure 4 The method comprises the following steps:

[0077] S310, controlling the auxiliary switch module to be turned on.

[0078] Normally, the negative poles of the connection ends of the photovoltaic modules in the photovoltaic string are grounded, so the potential of the negative pole on the output side of the circuit breaker is equal to zero potential. Therefore, turning on the auxiliary switch module is equivalent to: pulling down the positive pole potential on the output side of the circuit breaker to zero potential, so that step S310 can achieve the purpose of reducing the output side voltage of the circuit breaker to below the preset voltage value.

[0079] The specific process of the second implementation method is as follows Figure 6 As shown, the following steps are included:

[0080] S410, controlling the auxiliary switch module to be periodically turned on and off.

[0081] In one cycle, the ratio of the on-time to the off-time of the auxiliary switch module is greater than a preset proportion, and the preset proportion is the ratio of the on-time to the off-time of the auxiliary switch module when the output side voltage of the circuit breaker is equal to the preset voltage value.

[0082] Similar to the above, when the auxiliary switch module is turned on, the positive potential of the output side of the circuit breaker will be pulled down to zero potential.

[0083] Since the auxiliary switch module is controlled to be turned on and off periodically, it is equivalent to cyclically switching the positive electrode potential on the output side of the circuit breaker between the original potential and the zero potential, so the output side voltage of the circuit breaker can be reduced.

[0084] In practical applications, when the ratio of the time when the zero potential appears in one cycle to the time when the original potential appears is larger, that is, the ratio of the short-circuit time to the short-circuit release time is larger, the output side voltage of the circuit breaker is smaller.

[0085] Therefore, it can be seen that when the ratio of the on-time to the off-time of the auxiliary switch module within a cycle is greater than the preset proportion, since the preset proportion is the ratio of the on-time to the off-time of the auxiliary switch module when the output side voltage of the circuit breaker is equal to the preset voltage value, step S410 can achieve the purpose of reducing the output side voltage of the circuit breaker to below the preset voltage value.

[0086] The above are only two implementation methods of step S120. In practical applications, including but not limited to these, no specific limitation is made here and it may be determined according to the specific circumstances, all of which are within the protection scope of this application.

[0087] Another embodiment of the present application provides a circuit breaker, the specific structure of which is as follows: Figure 7 As shown, it specifically includes: a main switch module 10, a first controller 20 and at least one auxiliary switch module 30 ( Figure 7 Only one auxiliary switch module 30 is shown as an example); in the circuit breaker:

[0088] The negative pole on the input side of the circuit breaker is connected to the negative pole on the output side of the circuit breaker; the main switch module 10 is arranged between the positive pole on the input side of the circuit breaker and the positive pole on the output side of the circuit breaker, and the control end of the main switch module 10 is connected to the corresponding output end of the first controller 20.

[0089] Each auxiliary switch module 30 is disposed between the positive pole at the output side of the circuit breaker and the negative pole at the output side of the circuit breaker, and each auxiliary switch module is connected to the output end of the first controller 20 .

[0090] The first controller 20 is used to execute the control method of the circuit breaker provided in the above embodiment to prevent the current backflow between the photovoltaic strings with circuit breakers on the DC side of the inverter system.

[0091] In addition, the specific structure of the circuit breaker provided in this embodiment is roughly the same as the structure in the prior art, and the only difference is that the circuit breaker in this embodiment is additionally provided with an auxiliary switch module 30. Therefore, in addition to the control method provided in the above embodiment, the working principle of the circuit breaker provided in this embodiment is exactly the same as that in the prior art, and will not be repeated here.

[0092] This embodiment also provides another implementation of the circuit breaker, and its specific structure is as follows: Figure 8 As shown, in Figure 7 On the basis of, it also includes: a reverse cutoff module 40, a current detection module 50, an input side voltage detection module 60 and an output side voltage detection module 70.

[0093] The positive electrode of the reverse cutoff module 40 is connected to the negative electrode of the output side of the circuit breaker, and the negative electrode of the reverse cutoff module 40 is connected to the positive electrode of the output side of the circuit breaker.

[0094] Current detection module 50 (for simplified illustration, Figure 8 The figure also shows the communication connection between the current detection module 50 and the first controller 20), the input side voltage detection module 60 and the output side voltage detection module 70 are respectively communicatively connected with the corresponding communication ends of the first controller 20; the sampling end of the current detection module 50 is used to detect the output side current of the circuit breaker, the input side voltage detection module 60 is used to detect the input side current of the circuit breaker, and the output side voltage detection module 70 is used to detect the output side voltage of the circuit breaker.

[0095] Optionally, the auxiliary switch module can be a switch tube; in practical applications, including but not limited to this, no specific limitation is made here, it can be determined according to the specific circumstances, and all are within the protection scope of this application.

[0096] Another embodiment of the present application provides a photovoltaic string, the specific structure of which is as follows: Fig. 9 As shown, it specifically includes: N photovoltaic modules and N circuit breakers; in the photovoltaic string:

[0097] The circuit breaker is the circuit breaker provided in the above embodiment; the connection ends of the photovoltaic modules are connected to the input sides of the corresponding circuit breakers; the two poles of the output side of each circuit breaker are cascaded to the two poles of the connection end of the photovoltaic string.

[0098] Wherein, N is an integer greater than 1. In practical applications, the value may be determined according to the actual situation and is not specifically limited here.

[0099] This embodiment also provides a photovoltaic string, the specific structure of which is as follows: Fig.10 As shown, it specifically includes: a switch and at least two photovoltaic components; in the photovoltaic string:

[0100] The circuit breaker is the circuit breaker provided in the above embodiment; the two poles of the connection end of each photovoltaic module are cascaded to the two poles of the input side of the circuit breaker; the output side of the circuit breaker serves as the connection end of the photovoltaic string.

[0101] The above are only two implementation methods of photovoltaic strings. In practical applications, including but not limited to these, no specific limitations are made here. It can be determined according to the specific situation and is within the scope of protection of this application.

[0102] Another embodiment of the present application provides a photovoltaic system, whose specific structure is as follows: Fig.11 As shown, it specifically includes: a first inverter system 210, a first system controller 220, and at least two photovoltaic strings 230; in the photovoltaic system:

[0103] The connection ends of each photovoltaic string 230 are respectively connected to the DC side of the first inverter system 210, and the AC side of the first inverter system 210 serves as the AC side of the photovoltaic system; each photovoltaic string 230 selects the photovoltaic string 230 provided in the above embodiment; the first system controller 220 is respectively communicated with the controller in the circuit breaker in each photovoltaic string 230 and the first inverter system 210.

[0104] Since the photovoltaic strings 230 provided in the above embodiment are used, the photovoltaic system can prevent the current backflow between the photovoltaic strings 230 with circuit breakers on the DC side of the first inverter system 210 .

[0105] This embodiment provides an implementation of the first inverter system 210, and its specific structure is as follows: Fig.12 As shown, it specifically includes: a first inverter circuit 310, a first DC conversion circuit 320 and a second controller 330; in the first inverter system 210:

[0106] The first side of the first DC conversion circuit 320 serves as the DC side of the first inverter system 210, the second side of the first DC conversion circuit 320 is connected to the DC side of the first inverter circuit 310, and the AC side of the first inverter circuit 310 serves as the AC side of the first inverter system 210; the output ends of the second controller 330 are respectively connected to the control ends of the first DC conversion circuit 320 and the control ends of the first inverter circuit 310; the communication end of the second controller 330 is communicatively connected to the communication end of the first system controller 220.

[0107] Optionally, the first system controller 220 and the second controller 330 may be integrated together, or they may not be integrated together. This is not specifically limited here and may be determined according to specific circumstances. All of these are within the scope of protection of this application.

[0108] It should be noted that the structure and working principle of this implementation of the first inverter system 210 are exactly the same as those in the prior art, and are not specifically limited here. It may depend on the specific situation and is within the protection scope of this application.

[0109] Another embodiment of the present application provides a solar storage system, whose specific structure is as follows: Fig.13 As shown, it specifically includes: a second inverter system 310, an energy storage system 320, a second system controller 330 and at least two photovoltaic strings 230; in the photovoltaic storage system:

[0110] The connection ends of each photovoltaic string 230 are respectively connected to the DC side of the second inverter system 310, and the AC side of the second inverter system 310 serves as the AC side of the photovoltaic system; the connection port of the energy storage system 320 is connected to the DC side of the second inverter system 310; the photovoltaic string 230 uses the photovoltaic string 230 provided in the above embodiment; the second system controller 330 is respectively communicated with the controller in the circuit breaker in each photovoltaic string 230 and the second inverter system 310.

[0111] Since the photovoltaic strings 230 provided in the above embodiment are used, the photovoltaic system can prevent the current backflow between the photovoltaic strings 230 with circuit breakers on the DC side of the second inverter system 310 .

[0112] It should be noted that the second inverter system 310 is the same as the first inverter system 210 in the above embodiment, and will not be described again here. Please refer to the above description.

[0113] For the above description of the disclosed embodiments, the features recorded in each embodiment in this specification can be replaced or combined with each other, so that professionals in the field can implement or use the present application. The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as above with a preferred embodiment, it is not used to limit the present invention. Any technician familiar with the field can make many possible changes and modifications to the technical solution of the present invention using the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A method for controlling a circuit breaker, characterized in that: An auxiliary switch module is added between the two poles on the output side of the circuit breaker; The control method of the circuit breaker comprises: Determine whether the main switch module in the circuit breaker is turned off; wherein, when current backflow occurs between photovoltaic strings, the main switch module in the circuit breaker in the photovoltaic string with low string voltage is turned off; If the main switch module is turned off, the output side voltage of the circuit breaker is reduced to below a preset voltage value by controlling the auxiliary switch module to be turned on; the preset voltage value is the threshold voltage of the shutdown protection of the circuit breaker; the photovoltaic string with a high string voltage is connected in parallel with the photovoltaic string with a low string voltage, and the output side voltage of the circuit breaker in the photovoltaic string with a high string voltage is reduced to below the preset voltage value, and the circuit breaker in the photovoltaic string with a high string voltage enters shutdown protection.

2. The method for controlling a circuit breaker according to claim 1, characterized in that: Determining whether the main switch module in the circuit breaker is turned off includes: Determining whether the output side current of the circuit breaker is less than a preset current value; If the output side current of the circuit breaker is less than the preset current value, it is determined that the main switch module is turned off.

3. The method for controlling a circuit breaker according to claim 1 or 2, characterized in that: By controlling the auxiliary switch module, the output side voltage of the circuit breaker is reduced to below a preset voltage value, including: The auxiliary switch module is controlled to be turned on.

4. The method for controlling a circuit breaker according to claim 1 or 2, characterized in that: By controlling the auxiliary switch module, the output side voltage of the circuit breaker is reduced to below a preset voltage value, including: Controlling the auxiliary switch module to be turned on and off periodically; In one cycle, the ratio of the on-time to the off-time of the auxiliary switch module is greater than a preset proportion, and the preset proportion is the ratio of the on-time to the off-time when the output side voltage of the circuit breaker is equal to the preset voltage value.

5. A circuit breaker, characterized in that: include: A main switch module, a first controller and at least one auxiliary switch module; wherein: The negative electrode on the input side of the circuit breaker is connected to the negative electrode on the output side of the circuit breaker; The main switch module is arranged between the positive pole at the input side of the circuit breaker and the positive pole at the output side of the circuit breaker, and the control end of the main switch module is connected to the corresponding output end of the first controller; Each of the auxiliary switch modules is disposed between the positive electrode at the output side of the circuit breaker and the negative electrode at the output side of the circuit breaker, and each of the auxiliary switch modules is connected to the output end of the first controller; The first controller is used to execute the control method of the circuit breaker according to any one of claims 1 to 4.

6. The circuit breaker according to claim 5, characterized in that: Also includes: Reverse cutoff module, output current detection module, input side voltage detection module and output side voltage detection module The positive electrode of the reverse cutoff module is connected to the negative electrode of the output side of the circuit breaker, and the negative electrode of the reverse cutoff module is connected to the positive electrode of the output side of the circuit breaker; The current detection module, the input side voltage detection module and the output side voltage detection module are respectively communicatively connected to the corresponding communication ends of the first controller; the sampling end of the current detection module is used to detect the output side current of the circuit breaker, the input side voltage detection module is used to detect the input side voltage of the circuit breaker, and the output side voltage detection module is used to detect the output side voltage of the circuit breaker.

7. The circuit breaker according to claim 5 or 6, characterized in that: The auxiliary switch module includes: a switch tube.

8. A photovoltaic string, characterized in that: include: N photovoltaic modules and N circuit breakers; N is an integer greater than 1; wherein: The circuit breaker is a circuit breaker according to any one of claims 5 to 7; The connection ends of the photovoltaic modules are connected to the input sides of the circuit breakers in a one-to-one correspondence; The two poles at the output side of each of the circuit breakers are cascaded to the two poles at the connection end of the photovoltaic string.

9. A photovoltaic string, characterized in that: include: A circuit breaker and at least two photovoltaic modules; wherein: The circuit breaker is a circuit breaker according to any one of claims 5 to 7; The two poles of the connection end of each photovoltaic module are cascaded to the two poles of the input side of the circuit breaker; The output side of the circuit breaker serves as a connection end of the photovoltaic string.

10. A photovoltaic system, characterized in that: include: A first inverter system, a first system controller and at least two photovoltaic strings; wherein: The connection ends of the photovoltaic strings are respectively connected to the DC side of the first inverter system, and the AC side of the first inverter system serves as the AC side of the photovoltaic system; The photovoltaic string is the photovoltaic string as claimed in claim 8 or 9; The first system controller is respectively connected to the first controller in the circuit breaker in each of the photovoltaic strings and the first inverter system for communication.

11. The photovoltaic system according to claim 10, characterized in that: The first inverter system comprises: a first inverter circuit, a first DC conversion circuit and a second controller; wherein: The first side of the first DC conversion circuit serves as the DC side of the first inverter system, the second side of the first DC conversion circuit is connected to the DC side of the first inverter circuit, and the AC side of the first inverter circuit serves as the AC side of the first inverter system; The output terminals of the second controller are respectively connected to the control terminals of the first DC conversion circuit and the control terminals of the first inverter circuit; the communication terminal of the second controller is communicatively connected to the communication terminal of the first system controller.

12. The photovoltaic system according to claim 11, characterized in that: The first system controller is integrated with the second controller.

13. A solar energy storage system, characterized in that: include: A second inverter system, an energy storage system, a second system controller and at least two photovoltaic strings; wherein: The connection ends of the photovoltaic strings are respectively connected to the DC side of the second inverter system, and the AC side of the second inverter system serves as the AC side of the photovoltaic storage system; The connection port of the energy storage system is connected to the DC side of the second inverter system; The photovoltaic string is the photovoltaic string as claimed in claim 8 or 9; The second system controller is respectively connected to the first controller in the circuit breaker in each photovoltaic string and the second inverter system for communication.

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