Single-string photovoltaic power generation system and control method

Abstract

The invention discloses a single-string photovoltaic power generation system and a control method, and the system employs a structure that one photovoltaic inverter is only connected with one photovoltaic string, and only one photovoltaic string is connected, thereby avoiding the occurrence of a power line collection region, greatly reducing the risk of local overhigh temperature, and reducing the occurrence of safety accidents. Besides, by introducing the component monitor, control on whether each photovoltaic component is connected to the photovoltaic group string or bypassed can be realized, so that when the photovoltaic component breaks down, the whole photovoltaic power generation system can still keep an operation state by bypassing the photovoltaic component, and the power generation loss can be greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic power generation technology, and in particular to a single-string photovoltaic power generation system and control method. Background Technology

[0002] Photovoltaic inverters are an indispensable component of photovoltaic (PV) power generation systems. In existing PV systems, a single inverter typically connects to multiple PV strings, with these strings connected in parallel. This results in a large number of power lines converging in the area where multiple PV strings connect to the inverter, requiring cable trays and conduits for centralized management. This concentrated arrangement of power lines poses a risk of localized temperature increases and potential fire hazards, and also complicates construction. Furthermore, existing PV systems lack effective safety protection measures when PV modules fail, leaving only power outages and significant economic losses. Summary of the Invention

[0003] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a single-string photovoltaic power generation system to address safety and other issues arising from power line consolidation.

[0004] This invention also proposes a control method for a single-string photovoltaic power generation system.

[0005] A single-string photovoltaic power generation system according to a first aspect of the present invention includes:

[0006] A photovoltaic inverter has a set of string connection terminals and an inverter output terminal group, wherein the inverter output terminal group is used to connect to the power grid;

[0007] Multiple photovoltaic modules;

[0008] Multiple component monitors are configured one-to-one with multiple photovoltaic modules. The multiple photovoltaic modules are connected in series through the multiple component monitors to form a photovoltaic string. Each component monitor is used to control the connection of the corresponding photovoltaic module to the photovoltaic string or to bypass the corresponding photovoltaic module from the photovoltaic string. The photovoltaic string is connected to the set of string connection terminals.

[0009] The single-string photovoltaic power generation system according to embodiments of the present invention has at least the following beneficial effects:

[0010] The single-string photovoltaic (PV) power generation system of this invention employs a structure where one PV inverter connects to only one PV string. Because only one PV string is connected, the formation of power line convergence zones is avoided, significantly reducing the risk of localized overheating and thus minimizing the occurrence of safety accidents. Furthermore, by introducing a module monitor, it is possible to control whether each PV module is connected to the PV string or bypassed. This allows the entire PV power generation system to continue operating even if a PV module fails, by bypassing it, thereby greatly reducing power generation loss. In addition, the single-string PV power generation system of this invention is easy to standardize and modularize, effectively reducing production and subsequent maintenance costs.

[0011] According to some embodiments of the present invention, the photovoltaic inverter includes:

[0012] The inverter body has a positive input terminal, a negative input terminal, and an AC output terminal group, wherein the AC output terminal group is used to connect to the power grid.

[0013] String positive terminal;

[0014] The string negative terminal is connected to the negative input terminal of the inverter; the string positive terminal and the string negative terminal are used together to connect the photovoltaic string;

[0015] A string switch unit has a first connection terminal, a second connection terminal, a third connection terminal, a first driving device, and a second driving device. The first connection terminal and the second connection terminal form a first set of connection contacts, and the first connection terminal and the third connection terminal form a second set of connection contacts. The first connection terminal is connected to the positive terminal of the string, and the second connection terminal is connected to the positive input terminal. The first driving device is used to connect the first set of connection contacts and disconnect the second set of connection contacts when energized, and the second driving device is used to disconnect the first set of connection contacts and connect the second set of connection contacts when energized.

[0016] A string switch transistor has a controlled terminal, a first switch connection terminal, and a second switch connection terminal; the first switch connection terminal is connected to the first connection terminal; the second switch connection terminal is connected to the second connection terminal.

[0017] The string control unit is connected to the first driving device, the second driving device, and the controlled terminal respectively, and is used to change the energized state of the first driving device and the second driving device, and to control the controlled terminal to adjust the on / off state between the first switch connection terminal and the second switch connection terminal.

[0018] According to some embodiments of the present invention, the single-string photovoltaic power generation system further includes an energy storage device for storing electrical energy flowing through the single-string photovoltaic power generation system and for releasing the electrical energy stored in the energy storage device.

[0019] According to some embodiments of the present invention, the single-string photovoltaic power generation system further includes an emergency stop device, and the negative terminal of the string is connected to the positive input terminal through the emergency stop device.

[0020] According to some embodiments of the present invention, the single-string photovoltaic power generation system further includes a first wireless communication module connected to the string control unit.

[0021] According to some embodiments of the present invention, the single-string photovoltaic power generation system further includes a positioning module connected to the string control unit.

[0022] According to some embodiments of the present invention, the component monitor includes:

[0023] The component switching unit has a fourth connection terminal, a fifth connection terminal, a sixth connection terminal, a third driving device, and a fourth driving device. The fourth connection terminal and the fifth connection terminal form a third set of connection contacts, and the fourth connection terminal and the sixth connection terminal form a fourth set of connection contacts. The fifth connection terminal is used to connect to the first output terminal of the photovoltaic module, and the sixth connection terminal is used to connect to the second output terminal of the photovoltaic module. The third driving device is used to connect the third set of connection contacts and disconnect the fourth set of connection contacts when energized, and the fourth driving device is used to disconnect the third set of connection contacts and connect the fourth set of connection contacts when energized.

[0024] The component control unit is used to change the energized state of the third drive device and the energized state of the fourth drive device.

[0025] According to some embodiments of the present invention, the component monitor includes a second wireless communication module connected to the component control unit.

[0026] According to some embodiments of the present invention, the component control unit obtains operating power from the photovoltaic module.

[0027] According to some embodiments of the present invention, the component monitor further includes a first voltage sensor connected to the component control unit, the first voltage sensor being connected between the first output terminal and the second output terminal.

[0028] According to some embodiments of the present invention, the component monitor further includes a component current sensor connected to the component control unit, the component current sensor being connected in series between the fifth connection terminal and the first output terminal; the component monitor further includes a second voltage sensor connected to the component control unit, the second voltage sensor being connected between the sixth connection terminal and the fourth connection terminal.

[0029] A control method for a single-string photovoltaic power generation system according to a second aspect of the present invention is applied to the single-string photovoltaic power generation system described above; the control method for the single-string photovoltaic power generation system includes:

[0030] Obtain the operating data of each photovoltaic module in the photovoltaic string collected by the monitor of each component;

[0031] The operating status of each photovoltaic module is determined based on the operating data of each photovoltaic module;

[0032] When the photovoltaic module is in a fault state, the photovoltaic inverter is controlled to disconnect the photovoltaic string circuit.

[0033] Once the photovoltaic string circuit is disconnected, a bypass command is sent to the corresponding photovoltaic module with the fault, so that the photovoltaic module with the fault can be bypassed.

[0034] After the faulty photovoltaic module has bypassed, the photovoltaic inverter is controlled to connect the photovoltaic string circuit.

[0035] The control method for a single-string photovoltaic power generation system according to embodiments of the present invention has at least the following beneficial effects:

[0036] The single-string photovoltaic (PV) power generation method of this invention introduces a module monitor, which allows for control over whether each PV module is connected to the PV string or bypassed. This enables the entire PV power generation system to continue operating even when a PV module fails, by bypassing it and significantly reducing power loss. Furthermore, this invention employs a structure where one PV inverter connects to only one PV string. Because only one PV string is connected, the formation of power line convergence zones is avoided, greatly reducing the risk of localized overheating and thus minimizing the occurrence of safety accidents. Additionally, under the single-string PV power generation system architecture of this invention, the connection between the PV inverter and the PV string no longer requires numerous cable conduits and cable trays, significantly reducing the risk of fire.

[0037] According to some embodiments of the present invention, the photovoltaic inverter includes an inverter body, a string positive terminal, a string negative terminal, a string switching unit, a string switching transistor, and a string control unit. The inverter body has a positive input terminal, a negative input terminal, and an AC output terminal group, the AC output terminal group being used to connect to the power grid. The string negative terminal is connected to the negative input terminal of the inverter. The string positive terminal and the string negative terminal are used together to connect the photovoltaic string. The string switching unit has a first connection terminal, a second connection terminal, a third connection terminal, a first driving device, and a second driving device. The first connection terminal and the second connection terminal form a first set of connection contacts, and the first connection terminal and the third connection terminal form a second set of connection contacts. The first connection terminal is connected to the string positive terminal. The terminal is connected, with the second connection terminal connected to the positive input terminal; the first driving device is used to connect the first set of connection contacts and disconnect the second set of connection contacts after being energized, and the second driving device is used to disconnect the first set of connection contacts and connect the second set of connection contacts after being energized; the string switch has a controlled terminal, a first switch connection terminal and a second switch connection terminal; the first switch connection terminal is connected to the first connection terminal; the second switch connection terminal is connected to the second connection terminal; the string control unit is connected to the first driving device, the second driving device and the controlled terminal respectively, and is used to change the energized state of the first driving device and the second driving device, and to control the controlled terminal to adjust the on / off state between the first switch connection terminal and the second switch connection terminal;

[0038] The photovoltaic inverter disconnects the photovoltaic string circuit through the following steps:

[0039] The first and second switch connection terminals of the string switch transistor are turned on.

[0040] Once the first switch connection terminal and the second switch connection terminal are connected, the control power of the second drive device is switched on, so that the first set of connecting contacts is disconnected and the second set of connecting contacts is connected.

[0041] Disconnect the control power to the second drive device;

[0042] The first switch connection terminal and the second switch connection terminal are disconnected.

[0043] According to some embodiments of the present invention, the component monitor further includes a component current sensor connected to the component control unit, the component current sensor being connected in series between the fifth connection terminal and the first output terminal; the component monitor further includes a second voltage sensor connected to the component control unit, the second voltage sensor being connected between the sixth connection terminal and the fourth connection terminal;

[0044] The bypass completion instruction is obtained through the following steps:

[0045] Acquire the switch detection current data detected by the component current sensor and the switch detection voltage data detected by the second voltage sensor;

[0046] If the detected current data is zero and the detected switch voltage data is zero, a bypass completion command is generated.

[0047] According to some embodiments of the present invention, the component control unit obtains operating power from the photovoltaic module;

[0048] The fault in the photovoltaic module is determined by the following steps:

[0049] The photovoltaic inverter continuously monitors the wireless communication connection with multiple component monitors;

[0050] A fault is determined when the wireless communication connection with at least one of the component monitors is lost.

[0051] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0052] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0053] Figure 1 This is a system diagram of a single-string photovoltaic power generation system according to an embodiment of the present invention;

[0054] Figure 2 This is a simplified circuit diagram of a photovoltaic inverter according to an embodiment of the present invention;

[0055] Figure 3 This is a system diagram of a photovoltaic inverter according to an embodiment of the present invention;

[0056] Figure 4 This is a simplified circuit diagram of the component monitor according to an embodiment of the present invention;

[0057] Figure 5 This is a system diagram of the component monitor according to an embodiment of the present invention;

[0058] Figure 6 This is a flowchart of a single-string photovoltaic power generation system control method according to an embodiment of the present invention.

[0059] Figure label:

[0060] Photovoltaic inverter 100, inverter body 110, inverter unit 111, AC switch unit 112, input filter unit 113, output filter unit 114, string switch unit 121, string switch tube 122, string control unit 123, emergency stop device 130, first wireless communication module 140, positioning module 150, energy storage device 160;

[0061] Component monitor 200, component switch unit 210, component control unit 220, second wireless communication module 230, first voltage sensor 240, component current sensor 250, second voltage sensor 260;

[0062] Photovoltaic module 300. Detailed Implementation

[0063] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0064] In the description of this invention, the use of terms such as "first," "second," etc., is for the purpose of distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features indicated, or implicitly indicating the order of the technical features indicated.

[0065] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0066] In the description of this invention, it should be noted that, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0067] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are some embodiments of the present invention, not all embodiments.

[0068] See Figure 1 , Figure 1 This is a circuit diagram of a single-string photovoltaic power generation system according to an embodiment of the present invention. The single-string photovoltaic power generation system includes: a photovoltaic inverter 100, multiple photovoltaic modules 300, and multiple module monitors 200.

[0069] The photovoltaic inverter 100 has a set of string connection terminals and an inverter output terminal set, the inverter output terminal set being used to connect to the power grid;

[0070] Multiple photovoltaic modules 300;

[0071] Multiple component monitors 200 are configured one-to-one with multiple photovoltaic modules 300. The multiple photovoltaic modules 300 are connected in series through the multiple component monitors 200 to form a photovoltaic string. Each component monitor 200 is used to control the connection of the corresponding photovoltaic module 300 to the photovoltaic string or to bypass the corresponding photovoltaic module 300 from the photovoltaic string. The photovoltaic string is connected to a set of string connection terminals.

[0072] refer to Figures 1 to 5 After the photovoltaic modules 300 are connected to the module monitor 200, they no longer form photovoltaic strings by directly connecting adjacent photovoltaic modules 300. Instead, they are connected in series through the module monitor 200 corresponding to each photovoltaic module 300 to form strings. This allows the module monitor 200 to control the connection of the photovoltaic modules 300 to the photovoltaic strings and to bypass them within the strings. Therefore, even if a photovoltaic module 300 fails, bypassing it allows the entire photovoltaic power generation system to continue operating, significantly reducing power generation loss.

[0073] The single-string photovoltaic power generation system of this invention also adopts a structure where one photovoltaic inverter 100 is connected to only one photovoltaic string. Because only one photovoltaic string is connected, the formation of power line congestion areas can be avoided, thereby significantly reducing the risk of localized overheating and thus reducing the occurrence of safety accidents. Simultaneously, since there are no power line congestion areas, auxiliary structures for power line arrangement such as cable trays and cable ducts can be eliminated, greatly reducing installation difficulty and saving installation costs. Furthermore, the single-string photovoltaic power generation system of this invention is easy to standardize and modularize, thereby effectively reducing production costs and subsequent maintenance costs. Also, under the framework of the single-string photovoltaic power generation system of this invention, the connection between the photovoltaic inverter 100 and the photovoltaic string no longer requires a large number of cable ducts and cable trays, thereby greatly reducing the risk of fire.

[0074] Furthermore, in this embodiment of the invention, a single photovoltaic inverter 100 regulates and controls only one photovoltaic string, achieving optimal control and ensuring the photovoltaic string operates at its best power generation efficiency. Moreover, because the number of photovoltaic strings connected to a single photovoltaic inverter 100 is reduced, the heat generated by the inverter 100 is significantly reduced, eliminating the need for a fan for cooling. This increases the inverter's lifespan while allowing for a smaller overall size and more flexible placement of the inverter 100.

[0075] refer to Figure 2 , Figure 3 In some embodiments, the photovoltaic inverter 100 includes an inverter body 110, string positive terminals, string negative terminals, string switching unit 121, string switching transistor 122, and string control unit 123.

[0076] The inverter body 110 has a positive input terminal, a negative input terminal, and an AC output terminal group, the AC output terminal group being used to connect to the power grid;

[0077] The string negative terminal is connected to the negative input terminal of the inverter; the string positive terminal and the string negative terminal are used together to connect the photovoltaic string.

[0078] The string switch unit 121 has a first connection terminal, a second connection terminal, a third connection terminal, a first driving device, and a second driving device. The first connection terminal and the second connection terminal form a first set of connection contacts, and the first connection terminal and the third connection terminal form a second set of connection contacts. The first connection terminal is connected to the positive terminal of the string, and the second connection terminal is connected to the positive input terminal. The first driving device is used to connect the first set of connection contacts and disconnect the second set of connection contacts when energized, and the second driving device is used to disconnect the first set of connection contacts and connect the second set of connection contacts when energized.

[0079] The string switch transistor 122 has a controlled terminal, a first switch connection terminal, and a second switch connection terminal; the first switch connection terminal is connected to the first connection terminal; and the second switch connection terminal is connected to the second connection terminal.

[0080] The string control unit 123 is connected to the first driving device, the second driving device and the controlled terminal respectively, and is used to change the energized state of the first driving device and the second driving device, and to control the controlled terminal to adjust the on / off state between the first switch connection terminal and the second switch connection terminal.

[0081] The string switch 122 has good voltage and current surge resistance. When the photovoltaic string needs to be disconnected, the first set of connection contacts of the string switch unit 121 is bypassed by controlling the string switch 122 first, and then the first set of connection contacts of the string switch unit 121 is opened and the second set of connection contacts is closed. At this time, the voltage and current surges faced by the string switch unit 121 are much smaller, thus providing a basis for selecting a low-cost string switch unit 121. After the string switch unit 121 completes the connection contact adjustment, the power supply to the string switch unit 121 can be disconnected, and then the string switch 122 is opened, thus completing the circuit disconnection of the entire photovoltaic string. Furthermore, after the photovoltaic string circuit is disconnected, the module monitor 200 does not need to face high voltage and high current, thus reducing the cost of the module switch unit 210. That is, the technical solution in this embodiment of the invention can be implemented at a very low cost.

[0082] In addition, the string switch unit 121 uses a dual-drive structure, which allows for brief power supply only when the switch needs to be driven, and power supply can be stopped after the action is completed, thus greatly saving energy.

[0083] refer to Figure 2 , Figure 3 In some embodiments, the string switch 122 is an IGBT. The gate of the IGBT is connected to the string control unit 123, and the source and drain are connected to the first connection terminal and the second connection terminal, respectively. When the string control unit 123 outputs a control voltage to the gate of the IGBT, the IGBT is turned on, which connects the source and drain, thereby bypassing the first set of connection contacts. At this time, the string control unit 123 can switch the energized state of the control coil, so that the first set of connection contacts is disconnected and the second set of connection contacts is turned on.

[0084] refer to Figure 2 In some embodiments, the inverter body 110 includes an inverter unit 111 and an AC switching unit 112.

[0085] The inverter unit 111 has a first DC input terminal, a second DC input terminal, and an inverter AC output terminal group. The first DC input terminal is connected to the second connection terminal, and the second DC input terminal is connected to the negative terminal DC- of the string.

[0086] The AC switch unit 112 has a switch AC input terminal group and a switch AC output terminal group. The switch AC input terminal group is connected to the inverter AC input terminal group, and the switch AC output terminal group is used to output the AC power after inversion.

[0087] The inverter unit 111 can invert the DC power input to the photovoltaic string, so that the photovoltaic inverter 100 can be connected to the grid. The AC switch unit 112 can disconnect the AC circuit of a single-string photovoltaic power generation system, which can improve the safety and convenience of use.

[0088] refer to Figure 2 In some embodiments, the single-string photovoltaic power generation system further includes an input filter unit 113, which is used to filter the DC power input to the inverter unit 111. The input filter unit 113 can filter the DC side, thereby improving the quality of power conversion.

[0089] refer to Figure 2 In some embodiments, the single-string photovoltaic power generation system further includes an output filter unit 114, which is used to filter the AC power output by the inverter unit 111. The output filter unit 114 can filter the AC side, thereby improving the quality of the power output.

[0090] refer to Figure 3 In some embodiments, the single-string photovoltaic power generation system further includes an energy storage device 160, which stores electrical energy flowing through the single-string photovoltaic power generation system and releases the stored electrical energy. The energy storage device 160 can store excess electricity generated by the photovoltaic string and can release the stored electricity to the grid to supply power when the output of the photovoltaic inverter 100 is insufficient.

[0091] refer to Figure 2 In some embodiments, the single-string photovoltaic power generation system also includes an emergency stop device 130, through which the negative terminal of the string is connected to the positive input terminal. The emergency stop device 130 can perform emergency disconnection of the photovoltaic string, suitable for rapid local emergency protection in emergency situations. The emergency stop device 130 can be an emergency stop switch or other switching components with manual disconnection function. It should be noted that after the emergency stop device 130 performs an emergency operation, it can disconnect the AC switch unit 112, the string switch unit 121, and the module switch unit 210 with a single button, eliminating the risks posed by high voltage.

[0092] refer to Figure 3In some embodiments, the single-string photovoltaic power generation system also includes a first wireless communication module 140 connected to the string control unit 123. The photovoltaic inverter 100 needs to interact with the photovoltaic modules 300 to obtain operating data for each photovoltaic module 300 in the photovoltaic string. Using the first wireless communication module 140 can reduce the complexity of wiring and lower construction labor costs compared to a wired communication module. Furthermore, after the photovoltaic inverter 100 disconnects the photovoltaic string, carrier communication (a traditional solution that requires no additional wiring) becomes unusable; using the first wireless communication module 140 avoids this problem.

[0093] refer to Figure 3 In some embodiments, the single-string photovoltaic power generation system further includes a positioning module 150 connected to the string control unit 123. The positioning module 150 can achieve real-time positioning of the single-string photovoltaic power generation system, facilitating subsequent real-time monitoring of its operation and enabling asset management. In some embodiments, the positioning module 150 may employ a BeiDou positioning module, a GPS positioning module, or other single-core positioning modules, as well as a fusion positioning module.

[0094] In some embodiments, the single-string photovoltaic power generation system further includes an energy storage unit, and the string control unit 123 is used to obtain power from the inverter AC output terminal group of the energy storage unit and / or the first DC input terminal and the second DC input terminal of the inverter unit 111. Utilizing the energy storage unit, AC side, and DC side for redundant power supply can greatly ensure the stability of the string control unit 123's operation. Even if both the DC and AC sides are simultaneously powered off, it still has the capability to operate and quickly disconnect the photovoltaic string.

[0095] refer to Figure 4 , Figure 5 In some embodiments, the component monitor 200 includes a component switching unit 210 and a component control unit 220;

[0096] The component switching unit 210 has a fourth connection terminal, a fifth connection terminal, a sixth connection terminal, a third driving device, and a fourth driving device. The fourth connection terminal and the fifth connection terminal form a third set of connection contacts, and the fourth connection terminal and the sixth connection terminal form a fourth set of connection contacts. The fifth connection terminal is used to connect to the first output terminal of the photovoltaic module 300, and the sixth connection terminal is used to connect to the second output terminal of the photovoltaic module 300. The third driving device is used to connect the third set of connection contacts and disconnect the fourth set of connection contacts after being energized, and the fourth driving device is used to disconnect the third set of connection contacts and connect the fourth set of connection contacts after being energized.

[0097] The component control unit 220 is used to change the energized state of the third drive unit and the energized state of the fourth drive unit.

[0098] When the photovoltaic system is put into use, the third set of connection contacts is in a closed state, and the fourth set of connection contacts is in a closed state. At this time, the photovoltaic module 300 connected to the photovoltaic monitor is connected to the photovoltaic string through the photovoltaic monitor. When all photovoltaic modules 300 in the photovoltaic string are working normally, the photovoltaic string is in a normal working state. When a photovoltaic module 300 connected to the module monitor 200 malfunctions, in order to ensure that the photovoltaic string continues to generate electricity, the fourth drive device of the module switching unit 210 can be controlled by the module control unit 220 to open the third set of connection contacts and close the fourth set of connection contacts, so that the photovoltaic module 300 is disconnected from the photovoltaic string and bypassed by the module switching unit 210. This allows the remaining photovoltaic modules 300 in a normal state to continue to form a photovoltaic string for power generation. Furthermore, because the module switching unit 210 adopts a dual control coil control method, it only needs to be energized for a short time when the connection contacts need to be switched. Whether the photovoltaic module 300 is in normal connection or bypass mode, it does not need continuous power supply to maintain contact operation.

[0099] The component monitor 200 of this embodiment can bypass the photovoltaic module 300 through the component switching unit 210, and can also connect the photovoltaic module 300 to the photovoltaic string. This allows the string current flowing through the diode to be transferred to the component switching unit 210 when the photovoltaic module 300 malfunctions and the diode is turned on. The component switching unit 210 itself no longer uses a diode as a bypass device, effectively solving the heat generation problem caused by the diode. Simultaneously, because dual-coil control is used, the third or fourth drive device can be powered only when switching the state of the third and fourth sets of connection contacts. That is, power is only needed during switching; no energy is wasted when the photovoltaic module 300 is normally connected or bypassed, thus saving energy to a great extent. Furthermore, when the photovoltaic module 300 malfunctions and needs to be disconnected from the photovoltaic string, the component monitor 200 of this embodiment can also be used to bypass it, ensuring that the remaining photovoltaic modules 300 in normal condition can continue to generate electricity.

[0100] refer to Figure 4 , Figure 5In some embodiments, both the string switch unit 121 and the module switch unit 210 employ pulse-triggered control switches. Using a pulse-triggered control switch with two control coils, which switches to different connection contacts only when different coils are energized, is well-suited for application in the single-string photovoltaic power generation system of this embodiment. It should be noted that the module switch unit 210 can also be a standard single-coil driven changeover switch or relay, depending on actual needs. Furthermore, normally closed contacts can be used for connecting the photovoltaic module 300 to the photovoltaic string, while normally open contacts can be used for bypass operation.

[0101] refer to Figure 4 , Figure 5 In some embodiments, the component monitor 200 includes a second wireless communication module 230 connected to the component control unit 220. The component monitor 200 typically needs to interact with the photovoltaic inverter 100. Using the second wireless communication module 230 can reduce wiring complexity and lower construction labor costs compared to a wired communication module. Furthermore, the component monitor 200 usually draws power from the corresponding connected photovoltaic module 300. However, to reduce the cost of the component switching unit 210 (i.e., using a standard product instead of a high-voltage resistant one), during bypassing, the photovoltaic string is first disconnected through the photovoltaic inverter 100 before disconnecting the photovoltaic module 300. In this case, carrier communication (a traditional solution requiring no additional wiring) cannot be used. Using the second wireless communication module 230 avoids this problem.

[0102] In some embodiments, the component control unit 220 obtains operating power from the photovoltaic module 300. Since the component control unit 220 draws power directly from the photovoltaic module 300, it loses its operating power after the photovoltaic module 300 is bypassed by a diode. The component control unit 220 can wirelessly communicate with the photovoltaic inverter 100 via the second wireless communication module 230. When it loses its operating power, it can no longer communicate with the photovoltaic inverter 100, at which point the photovoltaic inverter 100 can determine that the photovoltaic module 300 has malfunctioned. At this time, the photovoltaic inverter 100 will disconnect the circuit in the photovoltaic string where the photovoltaic module 300 is located, so that the entire photovoltaic string is in an open circuit state. The bypass diode of the faulty photovoltaic module 300 will return to the off state. At this time, the photovoltaic module 300 will not be bypassed by the diode and can generate a small amount of electricity again. However, since it does not need to carry a large load, it can have a higher output voltage. The module control unit 220 can restart under the drive of this voltage. After the photovoltaic inverter 100 re-establishes a wireless connection with the module control unit 220, it can send a module bypass command to the module control unit 220. At this time, the module control unit 220 will control the module switching unit 210 to bypass the photovoltaic module 300. After the photovoltaic module 300 is bypassed, it will always be in an open circuit state, so it can continuously supply power to the module control unit 220, allowing the module switching unit 210 to always remain in the bypass state.

[0103] refer to Figure 4 , Figure 5 In some embodiments, the component monitor 200 further includes a first voltage sensor 240 connected to the component control unit 220, the first voltage sensor 240 being connected between the first output terminal and the second output terminal. The first voltage sensor 240 can detect the voltage of the photovoltaic module 300, facilitating the component control unit 220 to monitor the voltage data of the photovoltaic module 300, and each monitor in the photovoltaic string can transmit data in one step to the photovoltaic inverter 100 via the second wireless communication module 230, allowing the photovoltaic inverter 100 to monitor the voltage of all photovoltaic modules 300 in the entire string in real time.

[0104] refer to Figure 4 , Figure 5In some embodiments, the module monitor 200 further includes a module current sensor 250 connected to the module control unit 220, the module current sensor 250 being connected in series between the fifth connection terminal and the first output terminal; the module monitor 200 also includes a second voltage sensor 260 connected to the module control unit 220, the second voltage sensor 260 being connected between the sixth connection terminal and the fourth connection terminal. When the photovoltaic module 300 is normally connected to the string, the module current sensor 250 can detect the current of the photovoltaic module 300. When the module switching unit 210 bypasses the photovoltaic module 300, the module current sensor 250 will be in an open-circuit state, thus unable to detect the current. Using this characteristic, it can be determined whether the module switching unit 210 has successfully completed the bypass. When the photovoltaic module 300 is normally connected to the string, the second voltage sensor 260 can detect the voltage of the photovoltaic module 300. When the module switching unit 210 bypasses the photovoltaic module 300, the second voltage sensor 260 will be in a short-circuit state and will not be able to detect the voltage. Using this characteristic, it is possible to determine whether the module switching unit 210 has successfully bypassed the module, thus achieving closed-loop feedback for bypass control. After the second voltage sensor 260 and the module current sensor 250 are combined, it is possible to detect whether the fourth set of connection contacts is closed and whether the third set of connection contacts is open, thus achieving closed-loop feedback for bypass control.

[0105] Furthermore, in this embodiment, the AC switch unit 112, the string switch unit 121, and the component switch unit 210 can be linked together, providing a basis for one-button start-up and shutdown.

[0106] See Figure 3 As shown, Figure 3 A flowchart of a single-string photovoltaic power generation system control method according to an embodiment of the present invention is provided. The single-string photovoltaic power generation system control method includes, but is not limited to, the following steps:

[0107] Acquire the operating data of each photovoltaic module 300 in the photovoltaic string collected by each component monitor 200;

[0108] The operating status of each photovoltaic module 300 is determined based on the operating data of each photovoltaic module 300;

[0109] When the operating state of photovoltaic module 300 is a fault state, control photovoltaic inverter 100 to disconnect the photovoltaic string circuit.

[0110] Once the photovoltaic string circuit is disconnected, a module bypass command is sent to the faulty photovoltaic module 300 to enable the faulty photovoltaic module 300 to bypass.

[0111] After the faulty photovoltaic module 300 has been bypassed, the photovoltaic inverter 100 is controlled to connect the photovoltaic string circuit.

[0112] refer to Figures 1 to 6 After the photovoltaic modules 300 are connected to the module monitor 200, they no longer form photovoltaic strings by directly connecting adjacent photovoltaic modules 300. Instead, they are connected in series through the module monitor 200 corresponding to each photovoltaic module 300 to form strings. This allows the module monitor 200 to control the connection of the photovoltaic modules 300 to the photovoltaic strings and to bypass them within the strings. Therefore, even if a photovoltaic module 300 fails, bypassing it allows the entire photovoltaic power generation system to continue operating, significantly reducing power generation loss.

[0113] The single-string photovoltaic power generation method of this invention also adopts a structure in which a photovoltaic inverter 100 is connected to only one photovoltaic string. Because only one photovoltaic string is connected, the occurrence of power line convergence areas can be avoided, thereby significantly reducing the risk of local overheating and reducing the occurrence of safety accidents.

[0114] In some embodiments, the photovoltaic inverter 100 includes an inverter body 110, string positive terminals, string negative terminals, a string switching unit 121, a string switching transistor 122, and a string control unit 123. The inverter body 110 has a positive input terminal, a negative input terminal, and an AC output terminal group, which is used to connect to the power grid. The string negative terminals are connected to the negative input terminal of the inverter. The string positive terminals and string negative terminals are used together to connect the photovoltaic string. The string switching unit 121 has a first connection terminal, a second connection terminal, a third connection terminal, a first driving device, and a second driving device. The first connection terminal and the second connection terminal form a first set of connection contacts, and the first connection terminal and the third connection terminal form a second set of connection contacts. The first connection terminal is connected to the positive terminal of the string, and the second connection terminal is connected to the positive input terminal. The first driving device is used to connect the first set of connection contacts and disconnect the second set of connection contacts after being energized. The second driving device is used to disconnect the first set of connection contacts and connect the second set of connection contacts after being energized. The string switch tube 122 has a controlled terminal, a first switch connection terminal and a second switch connection terminal. The first switch connection terminal is connected to the first connection terminal. The second switch connection terminal is connected to the second connection terminal. The string control unit 123 is connected to the first driving device, the second driving device and the controlled terminal respectively, and is used to change the energized state of the first driving device and the second driving device, and to control the controlled terminal to adjust the on / off state between the first switch connection terminal and the second switch connection terminal.

[0115] The photovoltaic inverter 100 disconnects the photovoltaic string circuit through the following steps:

[0116] The first and second switch connection terminals of the control string switch transistor 122 are connected;

[0117] Once the first switch connection terminal and the second switch connection terminal are connected, the control power of the second drive device is switched on, so that the first set of connecting contacts is disconnected and the second set of connecting contacts is connected.

[0118] Disconnect the control power to the second drive unit;

[0119] Disconnect the first switch connection terminal and the second switch connection terminal.

[0120] The string switch 122 has good voltage and current surge resistance. When it is necessary to disconnect the photovoltaic string, the first set of connection contacts of the string switch unit 121 is bypassed by controlling the string switch 122 first, and then the first set of connection contacts of the string switch unit 121 is opened and the second set of connection contacts is closed. At this time, the voltage and current surges faced by the string switch unit 121 will be much smaller, thus providing a basis for selecting a low-cost string switch unit 121. After the connection contacts of the string switch unit 121 are adjusted, the power supply to the string switch unit 121 can be disconnected, and then the string switch 122 is opened, thus completing the circuit disconnection of the entire photovoltaic string. In this embodiment, the string switch 122 can bypass the string switch unit 121, so that when the string switch unit 121 is disconnected, it does not need to be subjected to the impact of large current and high voltage. This allows the string switch unit 121 to use a lower-cost switching device. The string switch 122 has strong current and voltage withstand capabilities, meeting the requirements for photovoltaic string disconnection, and its low cost further reduces the production cost of a single string photovoltaic inverter 100. In addition, the string switch unit 121 adopts a dual-drive structure, which allows for brief power supply only when the switch needs to be driven, and power supply can be stopped after the operation is completed, thus greatly saving energy.

[0121] In some embodiments, the component monitor 200 further includes a component current sensor 250 connected to the component control unit 220, the component current sensor 250 being connected in series between the fifth connection terminal and the first output terminal; the component monitor 200 also includes a second voltage sensor 260 connected to the component control unit 220, the second voltage sensor 260 being connected between the sixth connection terminal and the fourth connection terminal;

[0122] The bypass completion instruction is obtained through the following steps:

[0123] Acquire the switch detection current data detected by component current sensor 250 and the switch detection voltage data detected by second voltage sensor 260;

[0124] If the detected current data is zero and the switch detected voltage data is zero, a bypass completion command is generated.

[0125] Understandably, when the output circuit of the photovoltaic module 300 is cut off, the module current sensor 250 will inevitably not detect any current. Therefore, the module current sensor 250 can effectively determine whether the photovoltaic module 300 has been disconnected from the photovoltaic string. However, it cannot determine whether the string has been closed properly. Therefore, a second voltage sensor 260 is added. The second voltage sensor 260 can effectively determine whether the universal contacts next to the module switching unit 210 are closed properly. Furthermore, the second voltage sensor 260 can serve as a backup for the first voltage sensor 240, preventing the inability to continue providing voltage detection if the first voltage sensor 240 fails.

[0126] In some embodiments, the component control unit 220 obtains operating power from the photovoltaic module 300;

[0127] The fault in photovoltaic module 300 is determined by the following steps:

[0128] The photovoltaic inverter 100 continuously monitors and wirelessly communicates with multiple component monitors 200;

[0129] When the wireless communication connection with at least one component monitor 200 is lost, it is determined that the photovoltaic module 300 is faulty.

[0130] When the photovoltaic string is operating normally, each photovoltaic module 300 can generate electricity normally, and the corresponding module control unit 220 of each photovoltaic module 300 can draw power from the photovoltaic module 300 to maintain normal operation. At this time, each module control unit 220 can maintain a wireless communication connection with the photovoltaic inverter 100. When a photovoltaic module 300 is severely shaded and cannot generate electricity normally, the diode will bypass. At this time, the voltage at the output terminal of the photovoltaic module 300 drops to the diode's forward voltage, thus preventing it from supplying power to the module control unit 220. The photovoltaic inverter 100 will lose communication with the module monitor 200, and the photovoltaic module 300 corresponding to the module monitor 200 is determined to have malfunctioned. To restart the PV inverter 100 after it has stopped working, the photovoltaic inverter 100 disconnects the circuit, and the diodes return to the off state due to the circuit disconnection. While the photovoltaic module 300 cannot output high power normally, it can still output low power. Because the circuit is open, the photovoltaic module 300 does not need to carry a load, thus maintaining a relatively high output voltage. The previously de-energized PV inverter 220 can then use this weak output to restart and restore its wireless communication connection with the wireless gateway. Once the restored wireless communication connection is detected, the photovoltaic inverter 100 sends a bypass command to the module monitor 200 corresponding to the faulty photovoltaic module 300, instructing the PV inverter 220 to bypass the corresponding photovoltaic module 300. This ultimately isolates the faulty module from the string without affecting the normal power generation of other modules within the string.

[0131] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A single-string photovoltaic power generation system, characterized in that, include: A photovoltaic inverter has a set of string connection terminals and an inverter output terminal group, wherein the inverter output terminal group is used to connect to the power grid; Multiple photovoltaic modules; Multiple component monitors are configured one-to-one with multiple photovoltaic modules. The multiple photovoltaic modules are connected in series through the multiple component monitors to form a photovoltaic string. Each component monitor is used to control the connection of the corresponding photovoltaic module to the photovoltaic string or to bypass the corresponding photovoltaic module from the photovoltaic string. The photovoltaic string is connected to the set of string connection terminals.

2. The single-string photovoltaic power generation system according to claim 1, characterized in that, The photovoltaic inverter includes: The inverter body has a positive input terminal, a negative input terminal, and an AC output terminal group, wherein the AC output terminal group is used to connect to the power grid. String positive terminal; The string negative terminal is connected to the negative input terminal of the inverter; the string positive terminal and the string negative terminal are used together to connect the photovoltaic string; A string switch unit has a first connection terminal, a second connection terminal, a third connection terminal, a first driving device, and a second driving device. The first connection terminal and the second connection terminal form a first set of connection contacts, and the first connection terminal and the third connection terminal form a second set of connection contacts. The first connection terminal is connected to the positive terminal of the string, and the second connection terminal is connected to the positive input terminal. The first driving device is used to connect the first set of connection contacts and disconnect the second set of connection contacts when energized, and the second driving device is used to disconnect the first set of connection contacts and connect the second set of connection contacts when energized. A string switch transistor has a controlled terminal, a first switch connection terminal, and a second switch connection terminal; the first switch connection terminal is connected to the first connection terminal; the second switch connection terminal is connected to the second connection terminal. The string control unit is connected to the first driving device, the second driving device, and the controlled terminal respectively, and is used to change the energized state of the first driving device and the second driving device, and to control the controlled terminal to adjust the on / off state between the first switch connection terminal and the second switch connection terminal.

3. The single-string photovoltaic power generation system according to claim 2, characterized in that, The single-string photovoltaic power generation system also includes a first wireless communication module connected to the string control unit.

4. The single-string photovoltaic power generation system according to claim 2, characterized in that, The single-string photovoltaic power generation system also includes a positioning module connected to the string control unit.

5. The single-string photovoltaic power generation system according to claim 1, characterized in that, The component monitor includes: The component switching unit has a fourth connection terminal, a fifth connection terminal, a sixth connection terminal, a third driving device, and a fourth driving device. The fourth connection terminal and the fifth connection terminal form a third set of connection contacts, and the fourth connection terminal and the sixth connection terminal form a fourth set of connection contacts. The fifth connection terminal is used to connect to the first output terminal of the photovoltaic module, and the sixth connection terminal is used to connect to the second output terminal of the photovoltaic module. The third driving device is used to connect the third set of connection contacts and disconnect the fourth set of connection contacts when energized, and the fourth driving device is used to disconnect the third set of connection contacts and connect the fourth set of connection contacts when energized. The component control unit is used to change the energized state of the third drive device and the energized state of the fourth drive device.

6. The single-string photovoltaic power generation system according to claim 5, characterized in that, The component monitor includes a second wireless communication module connected to the component control unit.

7. The single-string photovoltaic power generation system according to claim 6, characterized in that, The component control unit obtains operating power from the photovoltaic module.

8. The single-string photovoltaic power generation system according to claim 5, characterized in that, The component monitor also includes a first voltage sensor connected to the component control unit, the first voltage sensor being connected between the first output terminal and the second output terminal.

9. The single-string photovoltaic power generation system according to claim 5, characterized in that, The component monitor also includes a component current sensor connected to the component control unit, the component current sensor being connected in series between the fifth connection terminal and the first output terminal; the component monitor also includes a second voltage sensor connected to the component control unit, the second voltage sensor being connected between the sixth connection terminal and the fourth connection terminal.

10. A control method for a single-string photovoltaic power generation system, characterized in that, The method is applied to a single-string photovoltaic power generation system as described in any one of claims 1 to 9; the control method for the single-string photovoltaic power generation system includes: Acquire the operating data of each photovoltaic module in the photovoltaic string collected by the monitor of each component; The operating status of each photovoltaic module is determined based on the operating data of each photovoltaic module; When the photovoltaic module is in a fault state, the photovoltaic inverter is controlled to disconnect the photovoltaic string circuit. Once the photovoltaic string circuit is disconnected, a bypass command is sent to the corresponding photovoltaic module with the fault, so that the photovoltaic module with the fault can be bypassed. After the faulty photovoltaic module has bypassed, the photovoltaic inverter is controlled to connect the photovoltaic string circuit.

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