Inverter access detection method, device and inverter system

Abstract

The present invention discloses an inverter access detection method, device and inverter system. The inverter access detection method comprises: before the inverter circuit of the inverter outputs power, measuring the first open circuit voltage of the first photovoltaic interface and the second open circuit voltage of the second photovoltaic interface; wherein the first photovoltaic interface and the second photovoltaic interface are any two of the multiple photovoltaic interfaces of the inverter; controlling the voltage disturbance of the first photovoltaic interface, and using the energy storage battery of the inverter to buffer the power input to the photovoltaic interface; measuring the first disturbance voltage of the first photovoltaic interface and the second disturbance voltage of the second photovoltaic interface after the disturbance; determining the access mode of the inverter according to the first open circuit voltage, the second open circuit voltage, the first disturbance voltage and the second disturbance voltage. The embodiment of the present invention enables the access detection method to meet the requirements of zero-power feeding of the power grid and the stable operation requirements of the load.

Description

Technical Field

[0001] The embodiments of the present invention relate to photovoltaic power generation technology, and in particular to an inverter access detection method, device and inverter system. Background Art

[0002] Inverters can not only provide power to the grid and / or loads to meet electricity demand, but also store excess photovoltaic energy as a reserve power when light energy is weak. Inverters meet the development needs of photovoltaic energy and have been widely used in recent years.

[0003] The inverter is generally equipped with multiple photovoltaic interfaces, and there are multiple ways to connect the multiple photovoltaic interfaces to the connected photovoltaic power generation devices. Different access methods correspond to different control strategies, so the inverter needs to determine the access method before executing the control strategy.

[0004] The current access mode determination method is to make a disturbance determination after turning on the inverter circuit of the inverter. However, this access mode determination method cannot meet the zero-power feeding requirements of the power grid and the stable operation requirements of the load. Summary of the invention

[0005] The present invention provides an inverter access detection method, device and inverter system, so that the access detection method can meet the requirements of zero-power feeding of power grid and the stable operation requirements of load.

[0006] In a first aspect, an embodiment of the present invention provides an inverter access detection method, the inverter access detection method comprising:

[0007] Before the inverter circuit of the inverter outputs power, measuring a first open-circuit voltage of a first photovoltaic interface and a second open-circuit voltage of a second photovoltaic interface; wherein the first photovoltaic interface and the second photovoltaic interface are any two of the multiple photovoltaic interfaces of the inverter;

[0008] Controlling the voltage disturbance of the first photovoltaic interface, and using the energy storage battery of the inverter to buffer the power input from the photovoltaic interface;

[0009] measuring a first disturbance voltage of the first photovoltaic interface and a second disturbance voltage of the second photovoltaic interface after the disturbance;

[0010] A connection mode of the inverter is determined according to the first open circuit voltage, the second open circuit voltage, the first disturbance voltage, and the second disturbance voltage.

[0011] Optionally, before controlling the voltage disturbance of the first photovoltaic interface, the method further includes:

[0012] The energy storage battery is controlled to start a charging mode and enable a current sinking loop.

[0013] Optionally, the bus loop includes a conversion circuit, and the conversion circuit is arranged between the DC bus and the energy storage battery;

[0014] The enabling bus loop includes:

[0015] The conversion circuit is controlled to absorb the power on the DC bus and input it into the energy storage battery.

[0016] Optionally, after determining the access mode of the inverter according to the first open-circuit voltage, the second open-circuit voltage, the first disturbance voltage, and the second disturbance voltage, the method further includes:

[0017] Control the energy storage battery to return to its original state; control the inverter circuit to start.

[0018] Optionally, the voltage disturbance includes a leftward disturbance;

[0019] Controlling a voltage disturbance of the first photovoltaic interface includes:

[0020] Control the reference voltage value of the primary side of the first transformer circuit to be lowered to a first preset value; wherein, the first transformer circuit is connected between the first photovoltaic interface and the DC bus, and the primary side of the first transformer circuit is the side of the first transformer circuit connected to the first photovoltaic interface.

[0021] Optionally, after determining the access mode of the inverter according to the first open-circuit voltage, the second open-circuit voltage, the first disturbance voltage, and the second disturbance voltage, the method further includes:

[0022] The reference voltage value of the primary side of the first voltage transformation circuit is restored to an original value.

[0023] Optionally, the value of the first preset value is positively correlated with the maximum output power of the inverter;

[0024] Furthermore, the value of the first preset value is positively correlated with the maximum access voltage of the inverter.

[0025] Optionally, a ratio of the first preset value to the maximum output power is less than a first preset ratio;

[0026] A ratio of the first preset value to the maximum access voltage is smaller than a second preset ratio.

[0027] Optionally, the access mode includes a parallel access mode and an independent access mode;

[0028] Wherein, the parallel access mode is an access mode in which at least two photovoltaic interfaces are simultaneously connected to the same photovoltaic power generation device, and the voltages of at least two photovoltaic interfaces change synchronously;

[0029] The independent access mode is an access mode in which at least two photovoltaic interfaces are respectively connected to different photovoltaic power generation devices at the same time, and the voltages of at least two photovoltaic interfaces do not affect each other.

[0030] Optionally, determining a connection mode of the inverter according to the first open circuit voltage, the second open circuit voltage, the first disturbance voltage, and the second disturbance voltage includes:

[0031] Determining whether voltage changes of the first photovoltaic interface and the second photovoltaic interface are synchronized according to the first open-circuit voltage, the second open-circuit voltage, the first disturbance voltage, and the second disturbance voltage;

[0032] If so, the access mode of the photovoltaic interface is the parallel access mode; otherwise, the access mode of the photovoltaic interface is the independent access mode.

[0033] Optionally, judging whether voltage changes of the first photovoltaic interface and the second photovoltaic interface are synchronized according to the first open-circuit voltage, the second open-circuit voltage, the first disturbance voltage, and the second disturbance voltage includes:

[0034] calculating a first difference between the first disturbance voltage and the second disturbance voltage;

[0035] calculating a second difference between the first open circuit voltage and the first disturbance voltage;

[0036] calculating a third difference between the second open circuit voltage and the second disturbance voltage;

[0037] If the first difference is smaller than a second preset value, and the difference between the second difference and the third difference is smaller than a third preset value, it is determined that the voltage changes of the first photovoltaic interface and the second photovoltaic interface are synchronized;

[0038] Otherwise, it is determined that the voltage changes of the first photovoltaic interface and the second photovoltaic interface are not synchronized.

[0039] In a second aspect, an embodiment of the present invention further provides an inverter access detection device, the inverter access detection device comprising: a first measurement module, a disturbance module, a second measurement module and an access mode determination module;

[0040] The first measuring module is used to measure a first open-circuit voltage of a first photovoltaic interface and a second open-circuit voltage of a second photovoltaic interface before the inverter outputs power; wherein the first photovoltaic interface and the second photovoltaic interface are any two of the multiple photovoltaic interfaces of the inverter;

[0041] The disturbance module is used to control the voltage disturbance of the first photovoltaic interface, and use the energy storage battery of the inverter to buffer the power input from the photovoltaic interface;

[0042] The second measuring module is used to measure a first disturbance voltage of the first photovoltaic interface and a second disturbance voltage of the second photovoltaic interface after the disturbance;

[0043] The access mode determination module is used to determine the access mode of the inverter according to the first open circuit voltage, the second open circuit voltage, the first disturbance voltage and the second disturbance voltage.

[0044] In the third aspect, an embodiment of the present invention further provides an inverter system, which includes: multiple photovoltaic interfaces, boost circuits corresponding one-to-one to the photovoltaic interfaces, energy storage batteries, conversion circuits, inverter circuits, and the inverter access detection device described in the second aspect.

[0045] The inverter access detection method, device and inverter system provided by the embodiment of the present invention determine the access mode before the inverter circuit in the inverter outputs power, and use the energy storage battery to buffer the power input to the photovoltaic interface during the voltage disturbance, thereby avoiding the impact of the sudden power caused by the introduction of disturbance on the power grid and the load during the access detection process. Before the inverter circuit works, the voltage disturbance of the first photovoltaic interface is controlled to determine whether other photovoltaic interfaces change accordingly, and then the access mode is determined according to whether other photovoltaic interfaces change accordingly, thereby realizing the detection of the inverter access mode. When the detection is performed, the inverter circuit has not yet been turned on, and power is not output to the power grid and the load. During the process of voltage disturbance at the photovoltaic interface, the power input to the photovoltaic interface is buffered by the photovoltaic storage battery, thereby avoiding the impact of the sudden power caused by the introduction of disturbance on the power grid and the load during the access mode detection process, so that the inverter adapts to the zero-power feeding requirements of the power grid and the stable operation requirements of the load. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A schematic diagram of the structure and connection relationship of an inverter in the prior art;

[0047] Figure 2 A schematic diagram of a PV curve of a photovoltaic power generation device provided in the prior art;

[0048] Figure 3 A schematic diagram of a flow chart of an inverter access detection method provided by an embodiment of the present invention;

[0049] Figure 4 A schematic flow chart of another inverter access detection method provided by an embodiment of the present invention;

[0050] Figure 5 A schematic flow chart of another inverter control method provided by an embodiment of the present invention;

[0051] Figure 6 A schematic diagram of a connection relationship of a parallel access method provided by an embodiment of the present invention;

[0052] Figure 7 A schematic diagram of a connection relationship of an independent access mode provided by an embodiment of the present invention;

[0053] Figure 8 A schematic diagram of another process for determining an inverter access mode provided by an embodiment of the present invention;

[0054] Fig. 9 A schematic diagram of another process for determining an inverter access mode provided by an embodiment of the present invention;

[0055] Fig.10 A schematic diagram of the structure of an inverter access detection device provided by an embodiment of the present invention;

[0056] Fig.11 A schematic structural diagram of an inverter system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0057] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0058] As the background technology, the existing access mode judgment method cannot meet the requirements of zero-power feeding of the power grid and the stable operation requirements of the load. The inventors have found that the reasons for this problem are as follows: Figure 1 The inverter 1000 includes multiple photovoltaic interfaces 1001. There are multiple access modes when connecting to a photovoltaic power generation device. For example, the access mode can be that multiple photovoltaic interfaces are connected to the same photovoltaic power generation device, or each photovoltaic interface is connected to a corresponding independent photovoltaic power generation device. However, different access modes correspond to different photovoltaic integrated machine control strategies. For example, the boost levels of each boost circuit 1002 can be controlled separately or in association. Therefore, it is necessary to determine the access mode in the initial stage of starting the inverter 1000. Figure 2, the current access mode determination method controls the access voltage of one photovoltaic interface 1001 to be disturbed from the open circuit voltage V0 to the left after turning on the boost circuit 1002 and the inverter circuit 1003, and then determines the access mode according to the voltage change trend of other photovoltaic interfaces 1001. However, when the photovoltaic power generation device generates a large amount of power, if this access mode determination method is used, the voltage of the boost circuit 1002 after the disturbance will be close to the voltage Vmppt of the maximum power point, so that the inverter circuit 1003 suddenly outputs a large amount of power to the power grid 1004, which cannot meet the zero-power feeding requirement of the power grid 1004. In addition, in the operating condition where the inverter 1000 is disconnected from the power grid and supplies power to the load 1003, if the current access mode determination method is used to determine the access mode, the power output of the inverter circuit 1003 to the load 1005 will fluctuate greatly due to the introduction of disturbance, which does not meet the load 1005's requirement for stable power.

[0059] In order to solve the above problem, an embodiment of the present invention provides an inverter access detection method, which can be executed by an inverter access detection device, and the device can be integrated in a controller of the inverter. Figure 3 A schematic diagram of a flow chart of an inverter access detection method provided by an embodiment of the present invention, combined with Figure 1 and Figure 3 , the inverter access detection method includes the following steps:

[0060] S101 . Before an inverter circuit of an inverter outputs power, measure a first open-circuit voltage of a first photovoltaic interface and a second open-circuit voltage of a second photovoltaic interface.

[0061] Wherein, before the inverter circuit outputs power refers to the situation that the inverter has just been turned on and has not yet started to output power to the grid and the load. At this time, the inverter circuit in the inverter has not yet started to work. Exemplarily, the situation that the inverter has not yet started to work can be to keep the first circuit breaker K1 between the inverter circuit 1003 and the first output interface a turned off, and keep the second circuit breaker K2 between the inverter circuit 1003 and the second output interface b turned off. Preferably, the situation that the inverter has not yet started to work can also be to keep the inverter circuit 1003 turned off or keep the connection between the inverter circuit 1003 and the DC bus 1007 disconnected, and keep the inverter circuit 1003 from outputting AC power to the load 1005 and the grid 1004.

[0062] Combination Figure 2, the open circuit voltage V0 refers to the voltage output by the photovoltaic power generation device in the working state connected to the photovoltaic interface 1001 when the inverter 1000 has not started working. The first open circuit voltage is the voltage output by the photovoltaic power generation device in the working state connected to the first photovoltaic interface when the inverter 1000 has not started working. Similarly, the second open circuit voltage is the voltage output by the photovoltaic power generation device in the working state connected to the second photovoltaic interface when the inverter has not started working.

[0063] Continue to combine Figure 1 The inverter 1000 includes multiple photovoltaic interfaces 1001, and the first photovoltaic interface and the second photovoltaic interface are any two of the multiple photovoltaic interfaces 1001 of the inverter 1000. For example, the inverter 1000 can be a photovoltaic storage integrated machine to achieve energy conversion, connection and control between the photovoltaic power generation equipment and the power grid or load. Figure 2 , the relationship between the output voltage and the corresponding output power of the photovoltaic power generation device satisfies the PV curve, and the line type of the PV curve is related to factors such as light intensity, incident angle and power generation efficiency of the photovoltaic power generation device. When the connected inverter 1000 has not started working (i.e., the power output of the photovoltaic power generation device is 0), the voltage output by the photovoltaic power generation device in normal operation is the open circuit voltage V0. Since the inverter 1000 has not started working, it does not consume the energy generated by the photovoltaic power generation device, so the output power is 0. At this time, the corresponding point on the PV curve is the right end point of the PV curve (i.e., the point corresponding to the open circuit voltage V0). Therefore, when measuring the open circuit voltage of the photovoltaic interface 1001, it is necessary to ensure that the inverter has not yet output power. At this time, the input power of the photovoltaic interface 1001 is 0. There are many ways to measure the first open circuit voltage of the first photovoltaic interface and the second open circuit voltage of the second photovoltaic interface. For example, a voltage sensing device can be set at the photovoltaic interface 1001 to measure the open circuit voltage, and the measurement value of the voltage sensor in the photovoltaic power generation device 1000 can also be obtained, which is not limited here.

[0064] S102: Control the voltage disturbance of the first photovoltaic interface, and use the energy storage battery of the inverter to buffer the power input to the photovoltaic interface.

[0065] Exemplarily, the inverter 1000 can adjust the output voltage of the photovoltaic power generation device by controlling the specific parameters of the boost circuit 1002 connected to the photovoltaic interface 1001. Preferably, the boost circuit 1002 can be a unidirectional boost circuit. There are many ways to control the voltage disturbance of the first photovoltaic interface. The boost circuit connected to the first photovoltaic interface can be started to control the boost circuit to start outputting power to the DC bus to control the voltage of the first photovoltaic interface to disturb to the left. At this time, the inverter circuit 1003 in the inverter 1000 has not started working yet, and does not output power to the power grid 1004 and the load. The power input to the inverter 1000 by the photovoltaic interface due to voltage disturbance can be buffered by the energy storage battery 1006. Exemplarily, buffering can include absorbing power, and the energy storage battery 1006 absorbs the power connected to the photovoltaic interface 1001 to prevent power mutation from affecting normal operation.

[0066] S103: Measure a first disturbance voltage of the first photovoltaic interface and a second disturbance voltage of the second photovoltaic interface.

[0067] Specifically, the leftward disturbance starts from the point corresponding to the open circuit voltage V0 in the PV curve, and reduces the voltage of the first photovoltaic interface, so that the power connected to the first photovoltaic interface also changes accordingly. After the disturbance ends, when the voltage of the first photovoltaic interface is stable, the voltage of the first photovoltaic interface measured at this time is the first disturbance voltage, and the voltage of the second photovoltaic interface measured is the second disturbance voltage.

[0068] S104, determining a connection mode of the inverter according to the first open circuit voltage, the second open circuit voltage, the first disturbance voltage, and the second disturbance voltage.

[0069] Among them, it can be determined whether the voltage of the second photovoltaic interface changes with the voltage disturbance of the first photovoltaic interface according to the first open-circuit voltage, the second open-circuit voltage, the first disturbance voltage and the second disturbance voltage. The output voltages of the multiple photovoltaic interfaces corresponding to the inverter of the same photovoltaic power generation device will change with the voltage disturbance of one photovoltaic interface, while the output voltages of the corresponding photovoltaic interfaces on the inverter of each independent photovoltaic power generation device are independent of each other, and the voltages of other photovoltaic interfaces will not change with the voltage disturbance of one photovoltaic interface. If it is determined that the voltage of the second photovoltaic interface changes with the voltage disturbance of the first photovoltaic interface, it is determined that the access mode of the inverter is parallel access, and if it is determined that the voltage of the second photovoltaic interface does not change with the voltage disturbance of the first photovoltaic interface, it is determined that the access mode of the inverter is parallel access. Among them, there can be multiple judgment indicators for the voltage of the second photovoltaic interface to change with the voltage disturbance of the first photovoltaic interface. For example, the voltage change trend caused by the disturbance of the second photovoltaic interface is the same as the voltage change trend caused by the disturbance of the first photovoltaic interface, or the voltage difference between the first photovoltaic interface and the second photovoltaic interface before and after the disturbance is small, which is not limited here.

[0070] The inverter access detection method provided in this embodiment determines the access mode before the inverter circuit in the inverter outputs power, and uses the energy storage battery to buffer the power input to the photovoltaic interface during the voltage disturbance, thereby avoiding the impact of the sudden power caused by the introduction of disturbance on the power grid and the load during the access detection process. By controlling the voltage disturbance of the first photovoltaic interface, it is determined whether other photovoltaic interfaces change accordingly, and then the access mode is determined according to whether other photovoltaic interfaces change accordingly, thereby realizing the detection of the inverter access mode. When the detection is performed, the inverter circuit has not yet been turned on, and no power is output to the power grid and the load. During the process of voltage disturbance at the photovoltaic interface, the power input to the photovoltaic interface is buffered by the photovoltaic storage battery, thereby avoiding the impact of the sudden power caused by the introduction of disturbance on the power grid and the load during the access mode detection process, so that the inverter can adapt to the zero-power feeding requirements of the power grid and the stable operation requirements of the load.

[0071] Optionally, Figure 4 A flow chart of another inverter access detection method provided by an embodiment of the present invention is shown in FIG. Figure 4 , the inverter access detection method includes the following steps:

[0072] S201. Control the inverter circuit in the inverter to remain closed.

[0073] Specifically, the input end of the inverter circuit 1003 is connected to the DC bus 1007, and can be connected to direct current. The output end of the inverter circuit 1003 is connected to the first output interface a and the second output interface b, respectively, and can provide alternating current for the power grid 1004 and the load 1005. By turning off the inverter circuit 1003, the power output of the inverter 1000 to the power grid 1004 and the load 1005 can be turned off, so as to prevent the pulse power input from the photovoltaic interface from affecting the power grid 1004 and the load 1005 during the detection of the access mode.

[0074] S202: Before the inverter circuit of the inverter outputs power, measure a first open-circuit voltage of the first photovoltaic interface and a second open-circuit voltage of the second photovoltaic interface.

[0075] Among them, step S202 is the same as the aforementioned step S102 and will not be repeated here.

[0076] S203: Set the energy storage battery in the inverter to a charging state and enable the busbar loop.

[0077] Among them, combined Figure 1The energy storage battery 1006 is connected to the photovoltaic interface via the DC bus 1007 to store photovoltaic power. The charging state refers to the state in which the energy storage battery 1006 absorbs power from the DC bus 1007 and stores it. The confluence loop includes the photovoltaic interface, the boost circuit 1002, the DC bus 1007 and the conversion circuit 1008. Enabling the confluence loop refers to controlling the line from the photovoltaic interface to the energy storage battery 1006 to remain conductive.

[0078] Specifically, the energy storage battery 1006 is connected to each photovoltaic interface 1001 via the conversion circuit 1008, the DC bus 1007 and each boost circuit 1002, and can store the photovoltaic power input by the photovoltaic interface 1001. After the energy storage battery 1006 is set to a charging state, the energy storage battery 1006 can absorb the power input by the photovoltaic interface 1001 during the voltage disturbance, thereby preventing the power output from affecting the power grid and the load.

[0079] The conversion circuit 1008 is arranged between the photovoltaic storage battery 1006 and the DC bus 1007. Enabling the bus loop can be to turn on the conversion circuit 1008, and control the conversion circuit 1008 to convert the voltage of the DC bus into the rated charging voltage of the energy storage battery, and control the voltage conversion circuit 1008 to absorb the power on the DC bus and input it into the energy storage battery. The conversion circuit 1008 can be a bidirectional DC / DC circuit, which can convert the voltage of the power input by the photovoltaic interface 1001 due to voltage disturbance, convert the power from the DC bus voltage to the rated charging voltage of the energy storage battery 1006, and input it into the energy storage battery 1006 to realize charging of the energy storage battery 1006.

[0080] S204: Control the voltage disturbance of the first photovoltaic interface, and use the energy storage battery of the inverter to buffer the power input to the photovoltaic interface.

[0081] S205 , measuring a first disturbance voltage of the first photovoltaic interface and a second disturbance voltage of the second photovoltaic interface.

[0082] S206: Determine a connection mode of the inverter according to the first open circuit voltage, the second open circuit voltage, the first disturbance voltage, and the second disturbance voltage.

[0083] Among them, S204, S205 and S206 respectively correspond to the same contents as S102, S103 and S104 in the aforementioned embodiment, and are not repeated here.

[0084] The inverter access detection method provided in this embodiment turns off the inverter circuit before controlling the photovoltaic interface voltage disturbance, and also turns on the charging function of the energy storage battery in the inverter, so that the electric energy input by the photovoltaic interface during the detection process is stored in the energy storage battery, thereby avoiding the influence of the photovoltaic interface input power fluctuation on the power grid and / or the load during the detection process, and reasonably storing the input electric energy for subsequent use.

[0085] Optionally, Figure 5 A flowchart of another inverter access detection method provided by an embodiment of the present invention is provided. Based on the above embodiment, combined with Figure 1 and Figure 5 The step S204 of controlling the voltage disturbance of the first photovoltaic interface includes:

[0086] The reference voltage value of the primary side of the first voltage conversion circuit is controlled to decrease by a first preset value.

[0087] The first voltage conversion circuit refers to the boost circuit 1002 corresponding to the first photovoltaic interface, and the primary side of the first voltage conversion circuit refers to the side where the first voltage conversion circuit is connected to the photovoltaic interface.

[0088] Specifically, the first voltage conversion circuit is a boost circuit 1002 disposed between the first photovoltaic interface and the DC bus 1007, which can perform voltage boost processing on the electrical signal input by the photovoltaic interface 1001 and output it to the DC bus 1007. By adjusting the parameters of the first voltage conversion circuit, the reference voltage level of the primary side of the first voltage conversion circuit can be controlled to decrease by a first preset value, so that the output voltage of the photovoltaic power generation device connected to the first photovoltaic interface is reduced from the open circuit voltage to the first preset value.

[0089] Optionally, based on the above embodiment, continue to refer to Figure 5 , the inverter access detection method includes the following steps:

[0090] S201. Control the inverter circuit in the inverter to remain closed.

[0091] S202: Before the inverter circuit of the inverter outputs power, measure a first open-circuit voltage of the first photovoltaic interface and a second open-circuit voltage of the second photovoltaic interface.

[0092] S203: Set the energy storage battery in the inverter to a charging state and enable the busbar loop.

[0093] S204: Control the voltage disturbance of the first photovoltaic interface, and use the energy storage battery of the inverter to buffer the power input to the photovoltaic interface.

[0094] S205 , measuring a first disturbance voltage of the first photovoltaic interface and a second disturbance voltage of the second photovoltaic interface.

[0095] S206: Determine a connection mode of the inverter according to the first open circuit voltage, the second open circuit voltage, the first disturbance voltage, and the second disturbance voltage.

[0096] S207, restore the reference voltage value of the primary side of the boost circuit to its original value.

[0097] The reference voltage is the input voltage setting value of the boost circuit 1002, which can be controlled by changing the parameters of the boost circuit 1002. The original value refers to the reference voltage value of the primary side of the boost circuit before the voltage is disturbed to the left.

[0098] Before the inverter 1000 officially starts working, it is necessary to restore the reference voltage on the primary side of the boost circuit 1002 to its original value. Officially starting working means that the inverter 1000 starts to connect the electric energy of the photovoltaic power generation device to the power grid 1004 or supply power to the load 1005 according to the control strategy corresponding to the access mode. The original value can be set according to demand and can be the open circuit voltage of the photovoltaic power generation device. Restoring the reference voltage value on the primary side of the boost circuit 1002 to its original value can prepare for the subsequent inverter 1000 to connect to the photovoltaic power source, connect the electric energy of the photovoltaic power source to the power grid 1004, or supply power to the load 1005.

[0099] S208, controlling the energy storage battery to return to its original state;

[0100] Among them, the original state of the energy storage battery 1006 refers to the preset state before the inverter 1000 starts to work formally. The original state can be any one of the discharge state, charging state or offline state, which can be set according to actual needs. The offline state can be disconnecting the energy storage battery 1006 from the DC bus 1007.

[0101] Specifically, before the inverter officially starts working, the energy storage battery 1006 needs to be restored to its original state to facilitate the implementation of subsequent control strategies.

[0102] S209, control the inverter circuit to start.

[0103] Specifically, the inverter circuit 1003 is controlled to be turned on, and the inverter circuit 1003 can output the power input by the photovoltaic interface to the power grid 1004 and / or the load 1005, so as to realize the photovoltaic power generation device being connected to the grid and / or powered. At this time, the self-checking link of the inverter 1000 is completed, and the photovoltaic power generation device can be controlled to be connected to the grid and / or powered according to the control strategy corresponding to the access mode, thereby avoiding control logic errors and improving the reliability of the inverter.

[0104] Optionally, based on the foregoing embodiment, the value of the first preset value is positively correlated with the maximum output power of the inverter; and the value of the first preset value is positively correlated with the maximum access voltage of the inverter.

[0105] The maximum output power refers to the upper limit of the inverter's output power. The maximum access voltage refers to the upper limit of the voltage that the inverter can access.

[0106] Specifically, the value of the first preset value is positively correlated with the maximum output power of the inverter and the maximum access voltage of the inverter, so that the voltage disturbance amplitude can be adapted to the parameters of the inverter. By introducing an appropriate disturbance voltage, the access mode can be judged to prevent excessive energy storage caused by excessive disturbance voltage, thereby further improving the reliability of the inverter access detection method.

[0107] Optionally, based on the foregoing embodiment, the ratio of the first preset value to the maximum output power is smaller than the first preset ratio, and the ratio of the first preset value to the maximum access voltage is smaller than the second preset ratio.

[0108] Specifically, the ratio of the first preset value to the maximum output power value is less than the first preset ratio, and the ratio of the first preset value to the maximum access voltage is less than the second preset ratio, so that the voltage of the first photovoltaic interface can be disturbed to the left by a small amplitude from the point where the open circuit voltage is located, and will not reach or exceed the MPPT point, so as to ensure that the first transformer circuit outputs a small power to the DC bus. For example, if the maximum output power of the inverter is 10kW and the maximum access voltage is 1100V, the first preset value can be 20V. In the process of controlling the reference voltage value on the primary side of the first transformer circuit to reduce the first preset value, the energy storage battery can absorb the power input by the photovoltaic interface. Controlling the ratio of the first preset value to the maximum output power, and the ratio of the first preset value to the maximum access voltage can further control the voltage disturbance amount to adapt to the inverter, and improve the reliability of the inverter access detection method.

[0109] Optionally, based on the foregoing embodiment, the access mode includes a parallel access mode and an independent access mode. Figure 6 A schematic diagram of a connection relationship of a parallel access method provided in an embodiment of the present invention, referring to Figure 6 The parallel access mode is an access mode in which at least two photovoltaic interfaces are simultaneously connected to the same photovoltaic power generation device, and the voltages of at least two photovoltaic interfaces change synchronously.

[0110] Figure 7 A schematic diagram of a connection relationship of an independent access mode provided in an embodiment of the present invention, referring to Figure 7 , the independent access mode is an access mode in which at least two photovoltaic interfaces are connected to different photovoltaic power generation devices at the same time, and the voltages of at least two photovoltaic interfaces do not affect each other. In addition, the access mode can also include a mixed access mode, that is, some photovoltaic interfaces are connected to the same photovoltaic power generation device, but other photovoltaic power generation interfaces are connected to different independent photovoltaic power generation devices.

[0111] Optionally, Figure 8 A schematic diagram of a flow chart of another method for determining an inverter access mode provided by an embodiment of the present invention, referring to Figure 8Based on the above embodiment, determining the access mode of the inverter according to the first open circuit voltage, the second open circuit voltage, the first disturbance voltage and the second disturbance voltage includes:

[0112] S301. Determine whether voltage changes of a first photovoltaic interface and a second photovoltaic interface are synchronized according to a first open-circuit voltage, a second open-circuit voltage, a first disturbance voltage, and a disturbance voltage.

[0113] There are many ways to determine whether the voltage changes of the first photovoltaic interface and the second photovoltaic interface are synchronized. For example, when the difference between the voltage change value of the second photovoltaic interface and the voltage change value of the first photovoltaic interface before and after the voltage disturbance is less than a preset value, it can be determined that the voltage changes of the first photovoltaic interface and the second photovoltaic interface are synchronized. It is also possible to determine that the voltage changes of the first photovoltaic interface and the second photovoltaic interface are synchronized when the voltage change trend of the second photovoltaic interface before and after the voltage disturbance is the same as the voltage change trend of the first photovoltaic interface. It is also possible to determine that the voltage changes of the first photovoltaic interface and the second photovoltaic interface are synchronized when the voltage difference between the first photovoltaic interface and the second photovoltaic interface before the disturbance is equal to the voltage difference between the first photovoltaic interface and the second photovoltaic interface after the disturbance, and the error is less than a preset error.

[0114] S302: If yes, the access mode of the photovoltaic interface is a parallel access mode.

[0115] Specifically, if the voltage of the first photovoltaic interface and the second photovoltaic interface change synchronously after controlling the voltage change on the primary side of the first transformer circuit, it can be determined that the photovoltaic power generation device connected to the first photovoltaic interface and the photovoltaic power generation device connected to the second photovoltaic interface are the same, and further it can be determined that the access mode of the photovoltaic interface is a parallel access mode.

[0116] S303. Otherwise, the access mode of the photovoltaic interface is an independent access mode.

[0117] Specifically, if after controlling the voltage change on the primary side of the first transformer circuit, the voltage changes of the first photovoltaic interface and the second photovoltaic interface are not synchronized, it can be determined that the photovoltaic power generation device connected to the first photovoltaic interface and the photovoltaic power generation device connected to the second photovoltaic interface are two independent photovoltaic power generation devices, and further it can be determined that the access mode of the photovoltaic interface is an independent access mode.

[0118] Optionally, Fig. 9 A flowchart of another inverter access detection method provided by an embodiment of the present invention, the inverter access detection method includes:

[0119] S401. Control the inverter circuit in the inverter to remain closed.

[0120] Specifically, the input end of the inverter circuit is connected to the mainstream busbar, and can be connected to direct current. The output end of the inverter circuit is connected to the output end of the power grid and the output end of the load, respectively, and can provide alternating current to the power grid and the load. Turning off the inverter circuit can turn off the inverter's power output to the power grid and the load, preventing the pulse power input from the photovoltaic interface during the access mode detection from damaging the power grid and the load.

[0121] S402: Setting the energy storage battery in the inverter to a charging state to store the input photovoltaic power.

[0122] Specifically, the energy storage battery in the inverter is connected to the photovoltaic interface via the DC bus and the boost circuit, and can store the photovoltaic power input from the photovoltaic interface or provide power to the grid and the load. After the energy storage battery is set to the charging state, the conversion circuit between the energy storage battery and the DC bus can be turned on. The conversion circuit is connected to the power supply of the DC bus, and the voltage level of the power supply is converted into the rated charging voltage of the energy storage battery and transmitted to the energy storage battery. The energy storage battery can absorb the power input from the photovoltaic interface during the voltage disturbance in the form of energy storage.

[0123] S403: Measure a first open-circuit voltage of the first photovoltaic interface and a second open-circuit voltage of the second photovoltaic interface.

[0124] Step S403 is identical to step S103 and will not be described again here.

[0125] S404: Control the reference voltage value of the primary side of the first transformer circuit to decrease to a first preset value.

[0126] Specifically, the first transformer circuit is connected between the first photovoltaic interface and the DC bus, and the primary side of the first transformer circuit is the side of the first transformer circuit connected to the first photovoltaic interface. The first transformer circuit can be a boost circuit arranged between the first photovoltaic interface and the DC bus, which can boost the electrical signal input by the photovoltaic interface and output it to the DC bus. By adjusting the parameters of the first transformer circuit, the reference voltage level of the primary side can be controlled to reduce the first preset value, so that the output voltage of the photovoltaic power generation device connected to the first photovoltaic interface is reduced from the open circuit voltage to the first preset value. Among them, the value of the first preset value is positively correlated with the maximum output power of the inverter and is also positively correlated with the maximum access voltage of the inverter. The ratio of the first preset value to the maximum output power value is less than the first preset ratio, and the ratio of the first preset value to the maximum access voltage is less than the second preset ratio, so that the voltage of the first photovoltaic interface can be disturbed to the left by an appropriate amplitude from the point where the open circuit voltage is located, and will not reach or exceed the MPPT point, and will not cause the voltage change relationship between the photovoltaic interfaces to be unable to be identified due to too small disturbance. Exemplarily, the first preset value can be 20V. In the process of controlling the reference voltage value of the primary side of the first voltage conversion circuit to decrease to the first preset value, the energy storage battery can absorb the power input by the photovoltaic interface.

[0127] S405 , measuring a first disturbance voltage of the first photovoltaic interface and a second disturbance voltage of the second photovoltaic interface.

[0128] Part of the content of step S405 is the same as that of step S102 and will not be repeated here.

[0129] S406: Determine whether voltage changes of the first photovoltaic interface and the second photovoltaic interface are synchronized according to the first open-circuit voltage, the second open-circuit voltage, the first voltage, and the second voltage.

[0130] Specifically, first, the first difference between the first disturbance voltage and the second disturbance voltage is calculated. Then, the second difference between the first open-circuit voltage and the first disturbance voltage is calculated, wherein the second difference can be equal to the first preset value, that is, the disturbance voltage of the first photovoltaic interface. Further, the third difference between the second open-circuit voltage and the second disturbance voltage is calculated. If the first difference is less than the second preset value, and the difference between the second difference and the third difference is less than the third preset value, it is determined that the voltage changes of the first photovoltaic interface and the second photovoltaic interface are synchronized. Otherwise, it is determined that the voltage changes of the first photovoltaic interface and the second photovoltaic interface are not synchronized. The second preset value is a numerical value set according to experience, which can be equal to 0.5 times the first preset value. If the first difference is less than the second preset value, it means that the voltage difference between the first photovoltaic interface and the second photovoltaic interface after the disturbance is small, and the photovoltaic power generation devices connected to the two photovoltaic interfaces can be identified as the same. The third preset value is also a numerical value set according to experience, which can be equal to 0.25 times the first preset value. If the difference between the second difference and the third difference is less than the third preset value, it can be said that the voltage changes of the two photovoltaic interfaces are not much different. When both of the above two conditions are met, it can be determined that the voltage of the second photovoltaic interface changes synchronously with the first photovoltaic interface; otherwise, it is determined that the voltage of the second photovoltaic interface does not change synchronously with the first photovoltaic interface.

[0131] S407: If yes, the access mode of the photovoltaic interface is a parallel access mode.

[0132] Specifically, if the voltage of the first photovoltaic interface and the second photovoltaic interface change synchronously after controlling the voltage change on the primary side of the first transformer circuit, it can be determined that the photovoltaic power generation device connected to the first photovoltaic interface and the photovoltaic power generation device connected to the second photovoltaic interface are the same, and further it can be determined that the access mode of the photovoltaic interface is a parallel access mode.

[0133] S408. Otherwise, the access mode of the photovoltaic interface is an independent access mode.

[0134] Specifically, if after controlling the voltage change on the primary side of the first transformer circuit, the voltage changes of the first photovoltaic interface and the second photovoltaic interface are not synchronized, it can be determined that the photovoltaic power generation device connected to the first photovoltaic interface and the photovoltaic power generation device connected to the second photovoltaic interface are two independent photovoltaic power generation devices, and further it can be determined that the access mode of the photovoltaic interface is an independent access mode.

[0135] S409: restore the reference voltage value of the primary side of the first transformer circuit to its original value.

[0136] Specifically, before the inverter officially starts working, the reference voltage on the primary side of the first transformer circuit needs to be restored to its original value, which refers to the reference voltage value before the voltage disturbance, and can be set according to demand, and can be the open-circuit voltage of the photovoltaic power generation device. This is done to prepare for the subsequent inverter to connect to the photovoltaic power source, connect the photovoltaic power source to the grid, or power the load.

[0137] S410, controlling the energy storage battery to return to its original state.

[0138] Specifically, before the inverter officially starts working, the energy storage battery needs to be restored to its original state, which refers to the set state after the inverter is turned on, and the detection of the access mode has not yet started. The original state can be any one of the discharge state, charging state or offline state, which can be set according to actual needs, where the offline state can be disconnecting the energy storage battery from the DC bus.

[0139] S411, control the inverter circuit to start.

[0140] Specifically, the inverter circuit is controlled to be turned on, so that the inverter circuit can output the power input by the photovoltaic interface to the power grid and / or the load, so as to realize the photovoltaic power generation device being connected to the grid and / or supplying power. At this time, the self-test link of the inverter is completed, and the photovoltaic power generation device can be controlled to be connected to the grid and / or supplying power according to the control method corresponding to the access mode.

[0141] The inverter access detection method provided in this embodiment first turns off the inverter circuit before controlling the disturbance of the first photovoltaic interface, controls the energy storage battery in the inverter to start the charging state to absorb the power input by the photovoltaic interface, prevents the pulse power input by the photovoltaic interface from affecting the power grid and the load during the access mode detection process, controls the reference voltage of the primary side of the first transformer circuit to make the voltage accessed by the first photovoltaic interface disturbed to the left, thereby determining the access mode of the photovoltaic interface according to whether the access voltages of the first photovoltaic interface and the second photovoltaic interface change synchronously, and realizes rapid determination of the access mode. The reduction amplitude of the reference voltage is positively correlated with the maximum access voltage and the maximum output power of the inverter, and ensures that the reduction amplitude is appropriate, avoiding the photovoltaic interface from inputting higher power in the process of confirming the access mode. After completing the access mode detection, the various parts of the inverter are restored to the state before the original access mode detection, which facilitates the implementation of subsequent control methods and improves the reliability and adaptability of the access detection method.

[0142] The embodiment of the present invention further provides an inverter access detection device, Fig.10 A schematic diagram of a structure of an inverter access detection device provided by an embodiment of the present invention, referring to Fig.10 The inverter access detection device includes: a first measurement module 601, a second measurement module 602, a disturbance module 603 and an access mode determination module 604; the first measurement module 601 is used to measure the first open circuit voltage of the first photovoltaic interface and the second open circuit voltage of the second photovoltaic interface before the inverter outputs power; wherein the first photovoltaic interface and the second photovoltaic interface are any two of the multiple photovoltaic interfaces of the inverter; the disturbance module 603 is used to control the voltage disturbance of the first photovoltaic interface and use the energy storage battery of the inverter to buffer the power input by the photovoltaic interface. The second measurement module 602 is used to measure the first disturbance voltage of the first photovoltaic interface and the second disturbance voltage of the second photovoltaic interface after the disturbance; the access mode determination module 604 is used to determine the access mode of the inverter according to the first open circuit voltage, the second open circuit voltage, the first disturbance voltage and the second disturbance voltage.

[0143] Optionally, based on the above-mentioned embodiment, the inverter access detection device further includes: a battery status control module and a bus-loop enabling module, wherein the battery status control module is used to control the energy storage battery to start the charging mode before the voltage disturbance to store the input photovoltaic power. The bus-loop enabling module is used to enable the bus-loop before the voltage disturbance to the left. The bus-loop enabling module includes a conversion circuit control unit, which is used to control the conversion circuit to absorb the power on the DC bus and input it to the energy storage battery.

[0144] Optionally, based on the aforementioned embodiment, the inverter access detection device further includes a recovery module, which is used to restore the reference voltage value on the primary side of the first transformer circuit to its original value after the access mode is determined, control the energy storage battery to return to its original state and control the inverter circuit to start.

[0145] Optionally, based on the above-mentioned embodiment, the disturbance module includes a reference voltage value control unit, which is used to control the reference voltage value on the primary side of the first transformer circuit to be reduced by a first preset value; wherein, the first transformer circuit is connected between the first photovoltaic interface and the DC bus, and the primary side of the first transformer circuit is the side of the first transformer circuit connected to the first photovoltaic interface.

[0146] Optionally, based on the above-mentioned embodiment, the access mode determination module includes a synchronization judgment unit and a mode determination unit, wherein the synchronization judgment unit is used to judge whether the voltage changes of the first photovoltaic interface and the second photovoltaic interface are synchronous according to the first open circuit voltage, the second open circuit voltage, the first disturbance voltage and the second disturbance voltage. The mode determination unit is used to determine that the access mode of the photovoltaic interface is a parallel access mode when the voltages of the first photovoltaic interface and the second photovoltaic interface change synchronously, otherwise, determine that the access mode of the photovoltaic interface is an independent access mode.

[0147] Optionally, based on the above-mentioned embodiment, the synchronization judgment unit includes a calculation component and a judgment component, the calculation component is used to calculate the first difference between the first disturbance voltage and the second disturbance voltage, calculate the second difference between the first open circuit voltage and the first disturbance voltage, and calculate the third difference between the second open circuit voltage and the second disturbance voltage. The judgment component is used to determine that the voltage changes of the first photovoltaic interface and the second photovoltaic interface are synchronized if the first difference is less than the second preset value, and the difference between the second difference and the third difference is less than the third preset value, otherwise determine that the voltage changes of the first photovoltaic interface and the second photovoltaic interface are not synchronized.

[0148] The embodiment of the present invention further provides an inverter system. Fig.11 A schematic diagram of the structure of an inverter system provided by an embodiment of the present invention, referring to Fig.11 On the basis of the above-mentioned embodiments, the inverter system includes a plurality of photovoltaic interfaces 1001, boost circuits 1002 corresponding to the photovoltaic interfaces one by one, energy storage batteries 1006, conversion circuits 1008, inverter circuits 1003 and any inverter access detection device 1009 provided in the above-mentioned embodiments.

[0149] In addition, the inverter system may further include a DC bus 1007, a first circuit breaker K1, a first output interface a, a second circuit breaker K2, and a second output interface b; the photovoltaic interface 1001 is connected to the DC bus 1007 via the corresponding boost circuit 1002; the energy storage battery 1006 is connected to the DC bus 1007 via the conversion circuit 1008; the input end of the inverter circuit 1003 is connected to the DC bus 1007, the first output end of the inverter circuit 1003 is connected to the first output interface a via the first circuit breaker K1, and the second output end b of the inverter circuit 1003 is connected to the second output interface b via the second circuit breaker K2; the inverter access detection device 1009 is respectively connected to the boost circuit 1002 and the energy storage battery 1006, and is used to execute any of the aforementioned inverter access detection methods.

[0150] The inverter access detection method, device and inverter system provided by the embodiment of the present invention determine the access mode before the inverter circuit in the inverter outputs power, and use the energy storage battery to buffer the power input to the photovoltaic interface during the voltage disturbance, thereby avoiding the impact of the sudden power caused by the introduction of disturbance on the power grid and the load during the access detection process. Before the inverter circuit works, the voltage disturbance of the first photovoltaic interface is controlled to determine whether other photovoltaic interfaces change accordingly, and then the access mode is determined according to whether other photovoltaic interfaces change accordingly, thereby realizing the detection of the inverter access mode. When the detection is performed, the inverter circuit has not yet been turned on, and power is not output to the power grid and the load. During the process of voltage disturbance at the photovoltaic interface, the power input to the photovoltaic interface is buffered by the photovoltaic storage battery, thereby avoiding the impact of the sudden power caused by the introduction of disturbance on the power grid and the load during the access mode detection process, so that the inverter adapts to the zero-power feeding requirements of the power grid and the stable operation requirements of the load.

[0151] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for detecting inverter access, characterized in that: include: Before the inverter circuit of the inverter outputs power, measuring a first open-circuit voltage of a first photovoltaic interface and a second open-circuit voltage of a second photovoltaic interface; wherein the first photovoltaic interface and the second photovoltaic interface are any two of the multiple photovoltaic interfaces of the inverter; Controlling the energy storage battery to start the charging mode and enabling the current converging loop, wherein enabling the current converging loop means controlling the line from the photovoltaic interface to the energy storage battery to remain conductive; Controlling the voltage disturbance of the first photovoltaic interface, and using the energy storage battery of the inverter to buffer the power input by the photovoltaic interface; measuring a first disturbance voltage of the first photovoltaic interface and a second disturbance voltage of the second photovoltaic interface after the disturbance; The access mode of the inverter is determined according to the first open circuit voltage, the second open circuit voltage, the first disturbance voltage and the second disturbance voltage, specifically including judging whether the voltage changes of the first photovoltaic interface and the second photovoltaic interface are synchronized according to the first open circuit voltage, the second open circuit voltage, the first disturbance voltage and the second disturbance voltage; if so, the access mode of the photovoltaic interface is a parallel access mode; otherwise, the access mode of the photovoltaic interface is an independent access mode.

2. The inverter access detection method according to claim 1, characterized in that: The bus loop includes a conversion circuit, which is arranged between the DC bus and the energy storage battery; The enabling converging loop includes: The conversion circuit is controlled to absorb the power on the DC bus and input it into the energy storage battery.

3. The inverter access detection method according to claim 1, characterized in that: After determining the access mode of the inverter according to the first open circuit voltage, the second open circuit voltage, the first disturbance voltage and the second disturbance voltage, the method further includes: Control the energy storage battery to return to its original state; control the inverter circuit to start.

4. The inverter access detection method according to claim 1, characterized in that: The voltage disturbance includes a leftward disturbance; Controlling a voltage disturbance of the first photovoltaic interface includes: Control the reference voltage value of the primary side of the first transformer circuit to be lowered to a first preset value; wherein, the first transformer circuit is connected between the first photovoltaic interface and the DC bus, and the primary side of the first transformer circuit is the side of the first transformer circuit connected to the first photovoltaic interface.

5. The inverter access detection method according to claim 4, after determining the access mode of the inverter according to the first open circuit voltage, the second open circuit voltage, the first disturbance voltage and the second disturbance voltage, further comprising: The reference voltage value of the primary side of the first voltage transformation circuit is restored to an original value.

6. The inverter access detection method according to claim 4, characterized in that: The value of the first preset value is positively correlated with the maximum output power of the inverter; Furthermore, the value of the first preset value is positively correlated with the maximum access voltage of the inverter.

7. The inverter access detection method according to claim 6, characterized in that: The ratio of the first preset value to the maximum output power is less than a first preset ratio; A ratio of the first preset value to the maximum access voltage is smaller than a second preset ratio.

8. The inverter access detection method according to claim 1, characterized in that: The access mode includes a parallel access mode and an independent access mode; Wherein, the parallel access mode is an access mode in which at least two photovoltaic interfaces are simultaneously connected to the same photovoltaic power generation device, and the voltages of at least two photovoltaic interfaces change synchronously; The independent access mode is an access mode in which at least two photovoltaic interfaces are respectively connected to different photovoltaic power generation devices at the same time, and the voltages of at least two photovoltaic interfaces do not affect each other.

9. The inverter access detection method according to claim 8, characterized in that: Judging whether voltage changes of the first photovoltaic interface and the second photovoltaic interface are synchronized according to the first open circuit voltage, the second open circuit voltage, the first disturbance voltage, and the second disturbance voltage, includes: calculating a first difference between the first disturbance voltage and the second disturbance voltage; calculating a second difference between the first open circuit voltage and the first disturbance voltage; calculating a third difference between the second open circuit voltage and the second disturbance voltage; If the first difference is smaller than a second preset value, and the difference between the second difference and the third difference is smaller than a third preset value, it is determined that the voltage changes of the first photovoltaic interface and the second photovoltaic interface are synchronized; Otherwise, it is determined that the voltage changes of the first photovoltaic interface and the second photovoltaic interface are not synchronized.

10. An inverter access detection device, characterized in that: include: A first measuring module, used for measuring a first open circuit voltage of a first photovoltaic interface and a second open circuit voltage of a second photovoltaic interface before the inverter outputs power; wherein the first photovoltaic interface and the second photovoltaic interface are any two of the multiple photovoltaic interfaces of the inverter; A disturbance module, used to control the energy storage battery to start the charging mode, enable the confluence loop, and then control the voltage disturbance of the first photovoltaic interface, and use the energy storage battery of the inverter to buffer the power input by the photovoltaic interface; A second measuring module, used for measuring a first disturbance voltage of the first photovoltaic interface and a second disturbance voltage of the second photovoltaic interface after disturbance; An access mode determination module is used to determine the access mode of the inverter according to the first open-circuit voltage, the second open-circuit voltage, the first disturbance voltage and the second disturbance voltage, and is specifically used to determine whether the voltage changes of the first photovoltaic interface and the second photovoltaic interface are synchronized according to the first open-circuit voltage, the second open-circuit voltage, the first disturbance voltage and the second disturbance voltage; if so, the access mode of the photovoltaic interface is a parallel access mode; otherwise, the access mode of the photovoltaic interface is an independent access mode.

11. An inverter system, characterized in that: include: A plurality of photovoltaic interfaces, a boost circuit corresponding to the photovoltaic interfaces one by one, an energy storage battery, a conversion circuit, an inverter circuit and the inverter access detection device as claimed in claim 10.

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