Photovoltaic power generation system and circuit breaker reverse connection detection method thereof

Abstract

The present invention provides a photovoltaic power generation system and a reverse connection detection method for a circuit breaker thereof. The method first determines whether a DC bus voltage of an inverter is greater than a first preset value. When the DC bus voltage is greater than the first preset value, if a photovoltaic string is normally connected, the voltage of the inverter input terminal connected thereto should be close to the DC bus voltage and greater than a second preset value. If the photovoltaic string is reversely connected, due to the presence of bypass diodes in each circuit breaker, the corresponding inverter input terminal voltage will be clamped to the sum of the conduction voltage drops of each bypass diode in the photovoltaic string, and the value is significantly less than the DC bus voltage and also less than the second preset value. Therefore, if at least one input terminal voltage among the input terminal voltages is less than the second preset value, it can be determined that the corresponding photovoltaic string is in a reverse connection state. The method is simple and easy to implement, and reverse connection detection of each photovoltaic string can be realized without changing the hardware circuit.

Description

Technical Field

[0001] The invention relates to the technical field of power electronics, and in particular to a photovoltaic power generation system and a circuit breaker reverse connection detection method thereof. Background Art

[0002] In a photovoltaic power generation system, if the photovoltaic strings at the input end are reversely connected, it will have an impact on the system. In the worst case, the photovoltaic strings connected to the inverter input end cannot generate electricity normally. In the worst case, the hardware at the inverter input end is damaged. Therefore, it is very important to detect the reverse connection of the photovoltaic strings at the inverter input in the photovoltaic power generation system.

[0003] Moreover, as the current grid-connected regulations attach importance to the shutdown of photovoltaic modules, more and more photovoltaic power generation systems have added circuit breakers to their photovoltaic modules. The structure of a typical photovoltaic power generation system with a circuit breaker is as follows: Figure 1 As shown; for the photovoltaic power generation system with a circuit breaker, the reverse connection detection of the photovoltaic strings has also become an important technology of the photovoltaic power generation system, but the existing detection scheme usually requires the addition of additional hardware equipment, and the judgment process is relatively complicated. Summary of the invention

[0004] In view of this, the present invention provides a photovoltaic power generation system and a circuit breaker reverse connection detection method thereof, which does not require changes to the hardware circuit and is simple and easy to implement.

[0005] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0006] A first aspect of the present invention provides a method for detecting reverse connection of a circuit breaker of a photovoltaic power generation system, wherein the photovoltaic power generation system comprises: an inverter and corresponding photovoltaic strings connected to each of its input terminals, each of the photovoltaic strings comprises at least two photovoltaic modules that output electric energy through a corresponding circuit breaker, and the output terminals of each of the circuit breakers are sequentially connected in series to form two ends of the photovoltaic string; the circuit breaker reverse connection detection comprises:

[0007] Determining whether the DC bus voltage of the inverter is greater than a first preset value;

[0008] If the DC bus voltage is greater than the first preset value, determining whether the voltages at each input terminal of the inverter are greater than a second preset value;

[0009] If at least one of the input terminal voltages is smaller than the second preset value, it is determined that the corresponding photovoltaic string is in a reverse connection state.

[0010] Optionally, before determining that the corresponding photovoltaic string is in a reverse connection state, the method further includes:

[0011] Determine whether the input terminal voltage that is less than the second preset value is less than the second preset value within a preset time;

[0012] If the corresponding input terminal voltage is less than the second preset value within the preset time, the step of determining that the corresponding photovoltaic string is in a reverse connection state is performed.

[0013] Optionally, after determining whether the voltages of the input terminals of the inverter are greater than a second preset value, the method further includes:

[0014] If the voltages at the input terminals are all greater than the second preset value, it is determined that the photovoltaic strings are not in a reverse connection state.

[0015] Optionally, after determining whether the input terminal voltage that is less than the second preset value is less than the second preset value within a preset time, the method further includes:

[0016] If there is a moment in which the corresponding input terminal voltage is greater than or equal to the second preset value within the preset time, it is determined that the corresponding photovoltaic string is not in a reverse connection state.

[0017] Optionally, before determining whether the DC bus voltage of the inverter is greater than a first preset value, the method further includes:

[0018] The inverter is powered on;

[0019] The inverter controls the circuit breaker in the corresponding photovoltaic string to output through the Boost circuit connected to the inner side of each input terminal of the inverter.

[0020] Optionally, the inverter controls the circuit breaker in the corresponding photovoltaic string to output through a Boost circuit connected to the inner side of each input terminal of the inverter, including:

[0021] The inverter controls each of the Boost circuits to form a preset waveform signal at the corresponding input end to wake up the circuit breaker in the corresponding photovoltaic string;

[0022] Each of the switches controls itself to output electric energy to the corresponding photovoltaic assembly.

[0023] Optionally, the preset waveform signal is: a high and low voltage signal that appears periodically.

[0024] Optionally, when the inverter includes only one Boost circuit, after the inverter is powered on, the method further includes:

[0025] The inverter controls the energy storage module inside itself to establish the DC bus voltage.

[0026] Optionally, the difference between the first preset value and the starting voltage of the inverter is less than a first preset difference;

[0027] The difference between the sum of the conduction voltage drops of the bypass diodes of all the circuit breakers in the photovoltaic string and the second preset value is smaller than the second preset difference.

[0028] The second aspect of the present invention also provides a photovoltaic power generation system, comprising: an inverter and at least two photovoltaic strings; wherein:

[0029] Each of the photovoltaic strings comprises at least two photovoltaic modules that output electrical energy through corresponding circuit breakers, and the output ends of the circuit breakers are sequentially connected in series to form two ends of the photovoltaic string;

[0030] Two ends of each of the photovoltaic strings are respectively connected to corresponding input ends of the inverter;

[0031] The controller in the inverter is used to execute the method for detecting reverse connection of a circuit breaker of a photovoltaic power generation system as described in any one of the first aspects above.

[0032] Optionally, the inverter comprises: the controller, an inverter circuit, a bus capacitor and at least two Boost circuits;

[0033] The input end of each Boost circuit is used as the corresponding input end of the inverter;

[0034] The output end of each of the Boost circuits and the DC side of the inverter circuit are respectively connected to a DC bus;

[0035] The bus capacitor is arranged between the positive and negative electrodes of the DC bus;

[0036] The inverter circuit and each of the Boost circuits are respectively controlled by the controller.

[0037] Optionally, the inverter includes: the controller, an inverter circuit, a bus capacitor, a Boost circuit and an energy storage module;

[0038] The input ends of the Boost circuit serve as the input ends of the inverter respectively;

[0039] The output end of the Boost circuit, the DC side of the inverter circuit and the energy storage module are respectively connected to a DC bus;

[0040] The bus capacitor is arranged between the positive and negative electrodes of the DC bus;

[0041] The inverter circuit and the Boost circuit are respectively controlled by the controller;

[0042] The energy storage module is used to establish a DC bus voltage after the inverter is powered on.

[0043] The invention provides a method for detecting reverse connection of a circuit breaker of a photovoltaic power generation system. The method first determines whether the DC bus voltage of the inverter is greater than a first preset value. When the DC bus voltage is greater than the first preset value, if the photovoltaic string is normally connected, the voltage of the inverter input terminal connected thereto should be close to the DC bus voltage and greater than a second preset value. If the photovoltaic string is reversely connected, due to the presence of bypass diodes in each circuit breaker, the corresponding inverter input terminal voltage will be clamped to the sum of the conduction voltage drops of each bypass diode in the photovoltaic string, which is significantly less than the DC bus voltage and also less than the second preset value. Therefore, if at least one of the input terminal voltages is less than the second preset value, it can be determined that the corresponding photovoltaic string is in a reverse connection state. The method is simple and easy to implement, and reverse connection detection of each photovoltaic string can be realized without changing the hardware circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings to be used in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description 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.

[0045] Figure 1 A schematic diagram of the structure of a photovoltaic power generation system provided by the prior art;

[0046] Figure 2 A flow chart of a method for detecting reverse connection of a circuit breaker of a photovoltaic power generation system provided by an embodiment of the present invention;

[0047] Figure 3 A schematic diagram of the structure of a circuit breaker provided in an embodiment of the present invention;

[0048] Figure 4 and Figure 5 Two other flow charts of the method for detecting reverse connection of a circuit breaker of a photovoltaic power generation system provided by an embodiment of the present invention;

[0049] Figure 6a and Figure 6b Two structural schematic diagrams of inverters provided in embodiments of the present invention;

[0050] Figure 7 A circuit diagram of a Boost circuit in an inverter provided by an embodiment of the present invention;

[0051] Figure 8 A partial flow chart of a method for detecting reverse connection of a circuit breaker of a photovoltaic power generation system provided by an embodiment of the present invention;

[0052] Figure 9a and Figure 9b They are two signal waveform diagrams provided in the embodiments of the present invention. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] In this application, the terms "comprises", "comprising" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising 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 sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0055] The present invention provides a method for detecting reverse connection of a switch of a photovoltaic power generation system, which does not require changes to a hardware circuit and is simple and easy to implement.

[0056] like Figure 1 As shown, the photovoltaic power generation system includes: an inverter 20 and at least two photovoltaic strings 10; wherein each photovoltaic string 10 includes at least two photovoltaic components 11 that output electrical energy through a corresponding circuit breaker 12, and the output ends of each circuit breaker 12 are sequentially connected in series to form the two ends of the photovoltaic string 10; the two ends of each photovoltaic string 10 are respectively connected to the corresponding input ends of the inverter 20; and the output end of the inverter 20 is connected to the power grid and / or the load.

[0057] The controller in the inverter 20 is used to perform the following reverse connection detection method, such as Figure 2 As shown, the reverse connection detection of the shutdown device includes:

[0058] S101. Determine whether a DC bus voltage of an inverter is greater than a first preset value.

[0059] The first preset value can be set according to the starting voltage of the inverter. The starting voltage means that if the DC bus voltage of the inverter reaches the starting voltage, the inverter can be started and work normally.

[0060] In practical applications, the difference between the first preset value and the starting voltage can be set to be smaller than the first preset difference; the value of the first preset difference is smaller and can be zero, depending on the specific application environment; the first preset value can be specifically set to 200V or 250V, etc. This is only an example and is not limited to this.

[0061] If the DC bus voltage is less than or equal to the first preset value, it means that the inverter cannot work normally at this time, or does not need to work, and the reverse connection detection of the photovoltaic strings can be omitted; if the DC bus voltage is greater than the first preset value, the reverse connection detection of the photovoltaic strings is required, and at this time, step S102 is executed first.

[0062] S102: Determine whether the voltage at each input terminal of the inverter is greater than a second preset value.

[0063] like Figure 3 As shown, each circuit breaker includes: a switch tube T arranged on the power transmission branch, and a bypass diode D reversely connected between the positive and negative electrodes of the output terminal of the corresponding circuit breaker. When the switch tube T is turned on, the circuit breaker can realize the power output of the corresponding photovoltaic module; when the bypass diode D is turned on, the corresponding photovoltaic module is bypassed.

[0064] If the photovoltaic strings are connected normally, since one inverter may have multiple photovoltaic strings with circuit breakers connected, and its bus voltage is determined by the string with the highest voltage, even if the line is not the highest voltage line, its input terminal voltage will be between the first preset value and the second preset value, that is, it will be greater than the second preset value; therefore, the input terminal voltage of the inverter connected to the normally connected photovoltaic strings should be close to or even the same as the DC bus voltage, and both are greater than the second preset value; in addition, in the current inverter, due to the presence of the input terminal sampling resistor, each input terminal will have a certain floating voltage, and the magnitude of the floating voltage is related to the magnitude of the DC bus voltage; due to the presence of this floating voltage, if the photovoltaic string of this line is not connected to the corresponding inverter input terminal, this input terminal will also detect a certain voltage value, and this voltage value is also greater than the second preset value.

[0065] However, if the PV string is reversely connected, due to the presence of the bypass diodes D in each circuit breaker, the bypass diodes D in the PV string will be connected in series and turned on, thereby clamping the voltage at the input end of the inverter to the sum of the conduction voltage drops of the bypass diodes D in the PV string; taking the conduction voltage drop of the bypass diode D as 1V as an example, if a PV string is connected to a maximum of 30 circuit breakers, its value will be about 30V, which will be significantly smaller than the DC bus voltage and also smaller than the second preset value.

[0066] In practical applications, the value of the second preset value can be selected according to the on-state voltage drop of the bypass diode D of the circuit breaker and the number of circuit breakers in the photovoltaic string. Specifically, the sum of the on-state voltage drops of the bypass diodes of all circuit breakers in the photovoltaic string can be set to be less than the second preset difference with the second preset value. For example, assuming that the on-state voltage drop of each bypass diode D is 1V, a photovoltaic string is connected to 30 circuit breakers, and considering the sampling error of about 10V, 40V can be selected as the second preset value at this time. That is, the second preset difference can be set according to the sampling accuracy of the actual application environment, but is not limited to this.

[0067] If the voltages of each input terminal are greater than the second preset value, step S103 can be executed, that is, it is determined that each photovoltaic string is not in a reverse connection state, such as a normal connection state or a disconnected state. If at least one of the input terminal voltages is less than the second preset value, such as 30V or 0V, step S104 can be executed.

[0068] S104: Determine whether the corresponding photovoltaic string is in a reverse connection state.

[0069] The photovoltaic power generation system's circuit breaker reverse connection detection method provided in this embodiment can detect whether each photovoltaic string connected to the inverter is in a reverse connection state through the above principle when the circuit breaker is connected. The method is simple and easy to implement, and does not require changes to the hardware circuit, which is conducive to promotion and application.

[0070] It is worth mentioning that when any PV string is detected to be reversely connected, the controller should issue an alarm to notify the operator to perform wiring correction operations, which will inevitably cause the inverter grid-connected time to be postponed. It may also be delayed for a long time due to the need to wait for the operator to arrive, such as one day or even multiple days, resulting in loss of power generation.

[0071] Therefore, it is necessary to avoid misjudgment. To achieve this goal, this embodiment is based on the previous embodiment. Preferably, the photovoltaic power generation system circuit breaker reverse connection detection method is as follows: Figure 4 As shown, before step S104, that is, before determining that the corresponding photovoltaic string is in a reverse connection state, it also includes:

[0072] S201, determining whether the input terminal voltage that is less than a second preset value is less than the second preset value within a preset time.

[0073] That is, it is determined whether the state in which the corresponding input terminal voltage is less than the second preset value can be maintained unchanged for a certain period of time; if it maintains this state within the preset time, that is, the corresponding input terminal voltage is less than the second preset value within the preset time, it means that this photovoltaic string is indeed reversely connected, and step S104 can be executed, that is, determining that the corresponding photovoltaic string is in a reverse connection state.

[0074] In practical applications, the value of the preset time can be selected according to the detection time requirement of the reverse connection alarm, for example, it can be set to 5s or 8s, etc.; it depends on the specific application environment and is within the protection scope of this application.

[0075] If the corresponding input terminal voltage fails to maintain this state within the preset time, that is, there is at least one moment when it is greater than or equal to the second preset value, step S103 is executed, that is, it is determined that the corresponding PV string is not in the reverse connection state.

[0076] This embodiment can not only realize the reverse connection detection of photovoltaic strings, but also avoid misjudgment and thus avoid the loss of power generation.

[0077] In addition, based on the above embodiment, the photovoltaic power generation system circuit breaker reverse connection detection method is as follows: Figure 5 (In Figure 2 As shown in FIG. 1 , before step S101, that is, before determining whether the DC bus voltage of the inverter is greater than the first preset value, the method further includes:

[0078] S301. Power on the inverter.

[0079] After the inverter is initially powered on, since the circuit breaker is disconnected by default, no voltage is established on the input side of the inverter, so step S302 is first required to execute the normal circuit breaker wake-up logic. After the circuit breakers of each photovoltaic string are gradually awakened, the voltage can be detected at each input terminal and DC bus of the inverter.

[0080] S302, the inverter controls the circuit breaker in the corresponding photovoltaic string to output through the Boost circuit connected to the inner side of each input terminal of the inverter.

[0081] like Figure 6a As shown, the inverter includes: a controller, an inverter circuit 201, a bus capacitor 202 and at least two Boost circuits 203; wherein the input end of each Boost circuit 203 serves as the corresponding input end of the inverter 20; the output end of each Boost circuit 203 and the DC side of the inverter circuit 201 are respectively connected to the DC bus; the bus capacitor 202 is arranged between the positive and negative poles of the DC bus; the inverter circuit 201 and each Boost circuit 203 are respectively controlled by the controller.

[0082] Each Boost circuit 203 can be as follows Figure 6a The basic Boost circuit shown in Figure 7 The three-level Boost circuit shown in the figure may also be other circuits, which are not specifically limited here and can be determined according to the application environment.

[0083] Or, if Figure 6b As shown, the inverter includes: a controller, an inverter circuit 201, a bus capacitor 202, a Boost circuit 203 and an energy storage module 204; wherein, the input end of the Boost circuit 203 is respectively used as the input end of the inverter; the output end of the Boost circuit 203, the DC side of the inverter circuit 201 and the energy storage module 204 are respectively connected to the DC bus; the bus capacitor 202 is arranged between the positive and negative poles of the DC bus; the inverter circuit 201 and the Boost circuit 203 are respectively controlled by the controller; in actual applications, the energy storage module 204 may include a battery module and a bidirectional DC / DC conversion module thereof, and the bidirectional DC / DC conversion module may also be controlled by the controller.

[0084] The step S302 specifically includes Figure 8 As shown in:

[0085] S311, the inverter controls each Boost circuit to form a preset waveform signal at the corresponding input end to wake up the circuit breaker in the corresponding photovoltaic string.

[0086] The preset waveform signal is: a high and low voltage signal that appears periodically, wherein each cycle specifically includes a high voltage maintained for a first duration and a low voltage maintained for a second duration; the high voltage can be a DC bus voltage, and the low voltage can be zero or a lower voltage value.

[0087] When the low voltage is zero, the driving signal of the switch tube in the corresponding Boost circuit is as follows: Figure 9a As shown in , it will short-circuit the DC bus. When the low voltage is a lower voltage value, the drive signal of the switch tube in the corresponding Boost circuit is as follows Figure 9b As shown, it is specifically a PWM (Pulse Width Modulation) signal.

[0088] It should be noted that for Figure 6a In the structure shown in FIG. 1 , through step S311, each Boost circuit 203 can be operated separately to form a preset waveform signal at the corresponding input terminal; and for Figure 6bIn the structure shown, before executing step S302, specifically before executing step S311, the inverter needs to first control the energy storage module 204 to provide the bus voltage, and then control the Boost circuit 203 to operate through step S311, thereby forming the preset waveform signal at the input end of the inverter.

[0089] In each circuit breaker and the inverter, corresponding programs may be set in advance to determine a preset waveform signal for awakening. When the circuit breaker detects that the voltage at its output terminal is the preset waveform signal, step S312 may be executed.

[0090] S312, each switch controls itself to output electric energy to the corresponding photovoltaic module.

[0091] After each circuit breaker performs output respectively, voltages can be detected at each input terminal and DC bus of the inverter, and then step S101 can be executed.

[0092] For other steps and specific principles of the circuit breaker reverse connection detection method, please refer to the above embodiments and will not be described in detail here.

[0093] Another embodiment of the present invention further provides a photovoltaic power generation system, which Figure 1 As shown, it specifically includes: an inverter 20 and at least two photovoltaic strings 10; wherein each photovoltaic string 10 includes at least two photovoltaic components 11 that output electrical energy through corresponding circuit breakers 12, and the output ends of each circuit breaker 12 are sequentially connected in series to form the two ends of the photovoltaic string 10; the two ends of each photovoltaic string 10 are respectively connected to the corresponding input ends of the inverter 20.

[0094] Among them, see Figure 3 Each circuit breaker includes: a switch tube T arranged on the power transmission branch, and a bypass diode D reversely connected between the positive and negative electrodes of the output terminal of the corresponding circuit breaker. When the switch tube T is turned on, the circuit breaker can realize the power output of the corresponding photovoltaic module; when the bypass diode D is turned on, the corresponding photovoltaic module is bypassed.

[0095] See also Figure 6a , the inverter 20 includes: a controller, an inverter circuit 201, a bus capacitor 202 and at least two Boost circuits 203. The input end of each Boost circuit 203 is used as the corresponding input end of the inverter 20; the output end of each Boost circuit 203 and the DC side of the inverter circuit 201 are respectively connected to the DC bus; the bus capacitor 202 is arranged between the positive and negative poles of the DC bus; the inverter circuit 201 and each Boost circuit 203 are respectively controlled by the controller. Or, Figure 6bAs shown, the inverter includes: a controller, an inverter circuit 201, a bus capacitor 202, a Boost circuit 203 and an energy storage module 204; wherein, the input end of the Boost circuit 203 is respectively used as the input end of the inverter; the output end of the Boost circuit 203, the DC side of the inverter circuit 201 and the energy storage module 204 are respectively connected to the DC bus; the bus capacitor 202 is arranged between the positive and negative poles of the DC bus; the inverter circuit 201 and the Boost circuit 203 are respectively controlled by the controller; in actual application, the energy storage module 204 may include a battery module and a bidirectional DC / DC conversion module thereof, and the bidirectional DC / DC conversion module may also be controlled by the controller; the energy storage module is used to establish a DC bus voltage after the inverter is powered on.

[0096] The controller in the inverter 20 is used to execute the method for detecting reverse connection of a switch of a photovoltaic power generation system as described in any of the above embodiments. The specific process and principle of the method can be referred to the above embodiments, and will not be described in detail here.

[0097] The same and similar parts between the various embodiments in this specification can refer to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiment. The system and system embodiments described above are only schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative work.

[0098] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0099] With respect to the above description of the disclosed embodiments, the features described in the various embodiments in this specification may be replaced or combined with each other to enable professionals in the field to implement or use the present invention. Various modifications to these embodiments will be apparent to professionals in the field, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for detecting reverse connection of a circuit breaker in a photovoltaic power generation system, characterized in that: The photovoltaic power generation system includes: an inverter and corresponding photovoltaic strings connected to each of its input terminals, each of the photovoltaic strings includes at least two photovoltaic modules that output electric energy through a corresponding circuit breaker, and the output terminals of each of the circuit breakers are sequentially connected in series to form two ends of the photovoltaic string; the circuit breaker reverse connection detection includes: Determining whether the DC bus voltage of the inverter is greater than a first preset value; If the DC bus voltage is greater than the first preset value, determining whether the voltages at each input terminal of the inverter are greater than a second preset value; If at least one of the input terminal voltages is smaller than the second preset value, it is determined that the corresponding photovoltaic string is in a reverse connection state.

2. The method for detecting reverse connection of a circuit breaker of a photovoltaic power generation system according to claim 1, characterized in that: Before determining that the corresponding photovoltaic string is in a reverse connection state, the method further includes: Determine whether the input terminal voltage that is less than the second preset value is less than the second preset value within a preset time; If the corresponding input terminal voltage is less than the second preset value within the preset time, the step of determining that the corresponding photovoltaic string is in a reverse connection state is performed.

3. The method for detecting reverse connection of a circuit breaker of a photovoltaic power generation system according to claim 1, characterized in that: After determining whether the voltages of the input terminals of the inverter are greater than a second preset value, the method further includes: If the voltages at the input terminals are all greater than the second preset value, it is determined that the photovoltaic strings are not in a reverse connection state.

4. The method for detecting reverse connection of a circuit breaker of a photovoltaic power generation system according to claim 2, characterized in that: After determining whether the input terminal voltage that is less than the second preset value is less than the second preset value within a preset time, the method further includes: If there is a moment in which the corresponding input terminal voltage is greater than or equal to the second preset value within the preset time, it is determined that the corresponding photovoltaic string is not in a reverse connection state.

5. The method for detecting reverse connection of a circuit breaker of a photovoltaic power generation system according to any one of claims 1 to 4, characterized in that: Before determining whether the DC bus voltage of the inverter is greater than a first preset value, the method further includes: The inverter is powered on; The inverter controls the circuit breaker in the corresponding photovoltaic string to output through the Boost circuit connected to the inner side of each input terminal of the inverter.

6. The method for detecting reverse connection of a circuit breaker of a photovoltaic power generation system according to claim 5, characterized in that: The inverter controls the circuit breaker in the corresponding photovoltaic string to output through the Boost circuit connected to the inner side of each input terminal of the inverter, including: The inverter controls each of the Boost circuits to form a preset waveform signal at the corresponding input end to wake up the circuit breaker in the corresponding photovoltaic string; Each of the switches controls itself to output electric energy to the corresponding photovoltaic assembly.

7. The method for detecting reverse connection of a circuit breaker of a photovoltaic power generation system according to claim 6, characterized in that: The preset waveform signal is: a high and low voltage signal that appears periodically.

8. The method for detecting reverse connection of a circuit breaker of a photovoltaic power generation system according to claim 5, characterized in that: When the inverter includes only one Boost circuit, after the inverter is powered on, the inverter further includes: The inverter controls the energy storage module inside itself to establish the DC bus voltage.

9. The method for detecting reverse connection of a circuit breaker of a photovoltaic power generation system according to any one of claims 1 to 4, characterized in that: The difference between the first preset value and the starting voltage of the inverter is less than the first preset difference; The difference between the sum of the conduction voltage drops of the bypass diodes of all the circuit breakers in the photovoltaic string and the second preset value is smaller than the second preset difference.

10. A photovoltaic power generation system, characterized in that: include: An inverter and at least two photovoltaic strings; wherein: Each of the photovoltaic strings comprises at least two photovoltaic modules that output electrical energy through corresponding circuit breakers, and the output ends of the circuit breakers are sequentially connected in series to form two ends of the photovoltaic string; Two ends of each of the photovoltaic strings are respectively connected to corresponding input ends of the inverter; The controller in the inverter is used to execute the method for detecting reverse connection of a circuit breaker of a photovoltaic power generation system as claimed in any one of claims 1 to 9.

11. The photovoltaic power generation system according to claim 10, characterized in that: The inverter comprises: the controller, an inverter circuit, a bus capacitor and at least two Boost circuits; The input end of each Boost circuit is used as the corresponding input end of the inverter; The output end of each of the Boost circuits and the DC side of the inverter circuit are respectively connected to a DC bus; The bus capacitor is arranged between the positive and negative electrodes of the DC bus; The inverter circuit and each of the Boost circuits are controlled by the controller respectively.

12. The photovoltaic power generation system according to claim 10, characterized in that: The inverter comprises: the controller, an inverter circuit, a bus capacitor, a Boost circuit and an energy storage module; The input ends of the Boost circuit serve as the input ends of the inverter respectively; The output end of the Boost circuit, the DC side of the inverter circuit and the energy storage module are respectively connected to a DC bus; The bus capacitor is arranged between the positive and negative electrodes of the DC bus; The inverter circuit and the Boost circuit are respectively controlled by the controller; The energy storage module is used to establish a DC bus voltage after the inverter is powered on.

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