A photovoltaic system and a method for networking optimizers thereof

Abstract

The application provides a photovoltaic system and an optimizer networking method thereof. The optimizer networking method first sets output voltage limit value and / or output current limit value for each optimizer by an inverter; then, the inverter controls each optimizer to start, and controls the input end of the corresponding Boost circuit to keep a short-circuit state for a preset time length according to a preset rule; since only the photovoltaic string connected to the input end of the corresponding Boost circuit is short-circuited when the input end of different Boost circuits is in the short-circuit state, the optimizer whose output electrical parameter changes is the optimizer in the corresponding photovoltaic string, and then the optimizer connected to each Boost circuit input end can be determined, the automatic networking of the connected optimizer in the photovoltaic system is realized, and the problems of low efficiency and easy error in manual input for realizing the optimizer networking are avoided.

Description

Technical Field

[0001] This application relates to the field of photovoltaic power generation technology, and in particular to a photovoltaic system and its optimizer networking method. Background Technology

[0002] The optimizer in a photovoltaic (PV) system, also known as a PV power optimizer, is specifically a DC-input, DC-output MLPE (Module Level Power Electronics). By connecting in series with the PV modules and employing predictive current and voltage technology, it ensures that the PV modules are always in optimal operating condition. This addresses the impact of shading, inconsistent orientation, or differences in module electrical specifications on power generation in PV power plants, achieving maximum power output from the PV modules and increasing system power generation.

[0003] In a solar photovoltaic power generation system with optimizers, the inverter and optimizer communicate via a PLC (Power Line Communication). The inverter contains a PLC master node controller, and the optimizer is a PLC slave node. After the optimizer and inverter are installed in the system, the inverter master node needs to know the topology location information of each optimizer connected to the inverter system to facilitate command control and status positioning during later operation. If the inverter lacks the topology location information of the optimizers, crosstalk may cause it to search for optimizers from other systems, affecting the inverter master node's judgment and error control.

[0004] However, the topology location information of each optimizer still needs to be manually entered in sequence. This makes the entire manual entry process for optimizing the network inefficient and prone to errors. Summary of the Invention

[0005] In view of this, this application provides a photovoltaic system and its optimizer networking method to avoid the problems of low efficiency and easy error when manually inputting data to realize optimizer networking.

[0006] To achieve the above objectives, this application provides the following technical solution:

[0007] The first aspect of this application provides an optimizer networking method for a photovoltaic system, the photovoltaic system including: an inverter and corresponding photovoltaic strings connected to each Boost circuit in the DC bus front stage; the optimizer networking method includes:

[0008] The inverter sets output voltage limit values ​​and / or output current limit values ​​for each of the optimizers;

[0009] The inverter controls the startup of each of the optimizers;

[0010] The inverter controls the corresponding Boost circuit input terminals to maintain a short-circuit state for a preset duration according to preset rules;

[0011] The inverter determines the optimizer connected to the input terminal of each Boost circuit based on the output electrical parameters of all optimizers under each short-circuit state.

[0012] Optionally, the inverter controls the corresponding Boost circuit input terminals to maintain a short-circuit state for a preset duration according to preset rules, including:

[0013] The inverter controls each Boost circuit input to maintain a short-circuit state for a preset duration; or...

[0014] The inverter groups all Boost circuits sequentially, and each time controls some of the Boost circuit input terminals in the current group to remain in a short-circuit state for a preset time. The current group is then grouped again according to the different states of the Boost circuit input terminals until the current group contains only one Boost circuit.

[0015] Optionally, the output electrical parameters include: output voltage, and / or, output current.

[0016] Optionally, the inverter determines the optimizer connected to the input terminal of each Boost circuit based on the output electrical parameters of all optimizers under each short-circuit state, including:

[0017] In each short-circuit state, for each optimizer whose output voltage is zero and / or whose output current is greater than a preset current value or is the output current limit value, the inverter determines that it is connected to the Boost circuit in the input short-circuit state; for each optimizer whose output voltage is not zero and / or whose output current is zero, the inverter determines that it is not connected to the Boost circuit in the input short-circuit state.

[0018] Optionally, before the inverter sets the output voltage limit value and / or output current limit value for each of the optimizers, the method further includes:

[0019] The inverter obtains the sequence number of the optimizer in each of the photovoltaic strings;

[0020] The inverter determines whether it has received manually entered topology location information;

[0021] If the topology location information is not received, the inverter performs the step of setting the output voltage limit value and / or output current limit value for each of the optimizers;

[0022] If the topology location information is received, the inverter determines whether each of the serial numbers matches the topology location information;

[0023] If the serial number does not match the topology location information, the inverter will perform the step of setting the output voltage limit value and / or output current limit value for each of the optimizers.

[0024] Optionally, if the inverter has already set the output voltage limit value for each of the optimizers, then after the inverter controls each of the optimizers to start, the method further includes:

[0025] Control the output voltage of each optimizer to reach the output voltage limit value;

[0026] Furthermore, before the inverter controls the corresponding Boost circuit input terminals to maintain a short-circuit state for a preset duration according to preset rules, the following steps are also included:

[0027] The inverter determines whether both ends of each photovoltaic string are connected in series by the output terminals of the corresponding optimizers based on the change in voltage at the input terminals of each Boost circuit before and after the optimization is started.

[0028] If so, the inverter determines the number of optimizers in the corresponding photovoltaic string based on the voltage at the input terminal of each Boost circuit, and executes the step of the inverter controlling the input terminals of the corresponding Boost circuits to maintain a short-circuit state for a preset duration according to preset rules.

[0029] Optionally, before the inverter controls the corresponding Boost circuit input terminals to maintain a short-circuit state for a preset duration according to preset rules, the method further includes:

[0030] The inverter determines whether the voltage of the DC bus is lower than a preset minimum threshold.

[0031] If the voltage of the DC bus is lower than the preset minimum threshold, the inverter controls at least one Boost circuit to charge the DC bus.

[0032] When the voltage of the DC bus reaches the preset minimum threshold, the inverter executes the step of controlling the corresponding Boost circuit input terminals to maintain a short-circuit state for a preset duration according to preset rules.

[0033] Optionally, the inverter controls the startup of each of the optimizers, including:

[0034] The inverter sends activation commands to each of the optimizers, causing each optimizer to enter the working mode and increase the output voltage through soft start.

[0035] A second aspect of this application also provides a photovoltaic system, comprising: an inverter and at least one photovoltaic string;

[0036] One or at least two optimizers with their outputs connected in series are provided between the two ends of the photovoltaic string, and the input of the optimizer is connected to at least one photovoltaic module.

[0037] The inverter is equipped with at least one Boost circuit in the front stage of the DC bus, and the input terminal of each Boost circuit is used to connect at least one corresponding photovoltaic string.

[0038] The controller in the inverter acts as a master node, communicates with each of the optimizers, and is used to execute the optimizer networking method of the photovoltaic system as described in any of the first aspects above.

[0039] Optionally, each Boost circuit is independent of the inverter; or,

[0040] Each Boost circuit is integrated into the inverter, and the output of each Boost circuit is connected to the DC side of the inverter circuit in the inverter through the DC bus.

[0041] Optionally, the input terminals of each Boost circuit are respectively connected to one connection port on the DC side of the inverter, or at least two connection ports connected in parallel.

[0042] The connection port connects to one of the photovoltaic strings, or the connection port connects to at least two of the photovoltaic strings in parallel via a bus terminal.

[0043] The photovoltaic system optimizer networking method provided in this application first involves the inverter setting output voltage and / or output current limits for each optimizer. Then, the inverter controls each optimizer to start, and then controls the corresponding Boost circuit input terminals to maintain a short-circuit state for a preset duration according to preset rules. Since only the photovoltaic string connected to the corresponding Boost circuit input terminal is short-circuited when different Boost circuit input terminals are in a short-circuit state, the optimizer whose output electrical parameters change is the optimizer within the corresponding photovoltaic string. This allows for the determination of the optimizer connected to each Boost circuit input terminal, achieving automatic networking of the optimizers connected in the photovoltaic system and avoiding the problems of low efficiency and easy errors when manually inputting optimizer networking. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0045] Figures 1 to 4 Four flowcharts are provided for the optimizer networking method of the photovoltaic system provided in the embodiments of this application;

[0046] Figure 5 This is a schematic diagram of the structure of a photovoltaic system provided in an embodiment of this application;

[0047] Figure 6 This is a schematic diagram of the structure of a photovoltaic string provided in an embodiment of this application;

[0048] Figure 7 This is a schematic diagram of the specific structure of the photovoltaic system provided in the embodiments of this application. Detailed Implementation

[0049] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] In this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0051] This application provides a method for optimizing the networking of photovoltaic systems to avoid the problems of low efficiency and easy error when manually inputting data to achieve optimizing the networking.

[0052] The photovoltaic system includes: an inverter, and the corresponding photovoltaic strings connected to the input terminals of each Boost circuit in the DC bus stage of the inverter; see [link to relevant documentation]. Figure 1 The optimizer networking method for this photovoltaic system includes:

[0053] S101, The inverter sets the output voltage limit value and / or output current limit value for each optimizer.

[0054] In practical applications, immediately after installation, when the photovoltaic modules connected to its input terminal can provide its normal operating voltage, the optimizer will enter a safe mode or shutdown mode, at which point its output voltage is 1V. Then, the inverter master node will send a network mode setting command to each optimizer, including the output voltage limit value Ulmt and / or the output current limit value Ilmt, to limit the output voltage and current of each optimizer. Furthermore, the values ​​of the output voltage limit value Ulmt and the output current limit value Ilmt can be set according to actual needs; for example, Ulmt can be set to 10V and Ilmt to 2A, but this is not the only possible setting.

[0055] If the inverter sets the output voltage limit value Ulmt for each optimizer, then when the output voltage of each optimizer is the output voltage limit value Ulmt, the voltage of the photovoltaic string obtained by connecting n optimizers in series through the output terminals will be n×Ulmt. The inverter can determine the number n of optimizers in the photovoltaic string connected to the input terminals of each Boost circuit by obtaining the voltage at the input terminals of each Boost circuit.

[0056] If the inverter sets the output current limit value Ilmt for each optimizer, then when the output terminal of the optimizer is short-circuited, its output current will not exceed the output current limit value Ilmt, thus ensuring the safety of the device.

[0057] S102, Inverter controls the startup of each optimizer.

[0058] In practical applications, the inverter master node can broadcast an activation command to each optimizer. Upon receiving the activation command, the optimizer will switch to operating mode, begin soft start, and gradually increase the output voltage. If the inverter has not set the output voltage limit value Ulmt for each optimizer, each optimizer can gradually increase the output voltage until the rated output voltage. If the inverter has set the output voltage limit value Ulmt for each optimizer, after each optimizer starts, the inverter can further control the output voltage of each optimizer to reach the output voltage limit value Ulmt, which can reduce voltage, improve safety, and facilitate subsequent judgment.

[0059] S103. The inverter controls the corresponding Boost circuit input terminals to maintain a short-circuit state for a preset duration according to preset rules.

[0060] In a photovoltaic system, the inverter master node can sequentially select one Boost circuit upstream of its DC bus according to a preset order, such as the software labeling order of the Boost circuits. It then controls the input voltage of this Boost circuit to gradually decrease to near 0V, creating a short circuit, and maintains this state for a period of time Tshort. The voltage decrease rate and the short-circuit holding time Tshort can be set according to actual needs and are not limited here. After the holding time Tshort ends, i.e., after the preset duration, the control state for that Boost circuit is canceled, and the input voltage of that Boost circuit is restored. Then, control is initiated on the next Boost circuit until all Boost circuits meeting the conditions have completed the above control. For example, the first Boost circuit can be controlled to be in a short-circuit state for a period of time and then restored, then the second Boost circuit can be controlled to be in a short-circuit state for a period of time and then restored, and so on, until all Boost circuits have completed the above control.

[0061] In practical applications, step S103 can be achieved through the above process, whereby the inverter controls each Boost circuit input terminal to maintain a short-circuit state for a preset duration. Alternatively, the inverter can group all Boost circuits sequentially, controlling a portion of the Boost circuit input terminals in the current group to maintain a short-circuit state for a preset duration each time, and then regrouping the current group based on the different states of the Boost circuit input terminals until the current group contains only one Boost circuit. That is, the inverter first divides all Boost circuits into two groups, one group is short-circuited at the input terminal, and the other group does not operate; the second time, the two large groups are further divided into two smaller groups, with one smaller group short-circuited at the input terminal and the other smaller group not operating; and so on, until all Boost circuits are grouped into one group. In practical applications, input short-circuit control can be applied to half of the Boost circuits in the current group each time. For example, the first time, input short-circuit control is applied to n / 2 of the Boost circuits, resulting in two large groups. The second time, input short-circuit control is applied to n / 4 of the Boost circuits in each of the two large groups. The third time, input short-circuit control is applied to n / 8 of the Boost circuits in the previous four groups, until all Boost circuits are grouped. This process can reduce the overall time of step S103 and is suitable for situations where there are a large number of optimizers in a photovoltaic system.

[0062] It is worth noting that the preset duration for maintaining the short-circuit state each time is preferably the same; of course, it can also be different, depending on the specific application environment, and all of them are within the protection scope of this application.

[0063] S104. The inverter determines the optimizer connected to the input terminal of each Boost circuit based on the output electrical parameters of all optimizers under each short-circuit state.

[0064] The output electrical parameters include: output voltage, and / or, output current.

[0065] When different Boost circuit inputs are short-circuited, only the photovoltaic string connected to the corresponding Boost circuit input is short-circuited. The optimizer whose output electrical parameters change is the optimizer in the corresponding photovoltaic string, and thus the optimizer connected to each Boost circuit input can be determined.

[0066] Specifically, when each Boost circuit's input is short-circuited: if an output current limit of Ilmt and an output voltage limit of Ulmt have been previously set for the optimizer, the optimizer connected to the Boost circuit's input will operate with an output voltage of 0V and an output current limit of Ilmt. Optimizers not connected to the Boost circuit's input will maintain an output voltage limit of Ulmt and an output current of 0A. If no output current limit of Ilmt has been set for the optimizer, the output voltage of the optimizer connected to the Boost circuit's input will also be 0V, but its output current will be a short-circuit current greater than the preset current value. If no output voltage limit of Ulmt has been set for the optimizer, the output current of the optimizer not connected to the Boost circuit's input will also be 0A, but its output voltage will be a rated voltage greater than 0V.

[0067] In other words, under each short-circuit condition, for each optimizer with an output voltage of 0V and / or an output current greater than the preset current value or the output current limit value Ilmt, the inverter can determine that it is connected to the Boost circuit in the input short-circuit state; while for each optimizer with an output voltage not of 0V and / or an output current of 0A, the inverter will determine that it is not connected to the Boost circuit in the input short-circuit state.

[0068] Therefore, based on the differences in the output voltage and / or output current of each optimizer, the inverter can identify all optimizers connected to the input of the Boost circuit.

[0069] The photovoltaic system optimizer networking method provided in this embodiment involves three steps: setting the optimizer's output electrical parameters, controlling the optimizer's startup, and controlling the short circuit at the Boost circuit input. Based on the difference in electrical state between the optimizer connected to that Boost circuit and other optimizers when the Boost circuit is controlled in a short-circuit state, the optimizer connected to that Boost circuit can be automatically identified. By sequentially controlling each Boost circuit, an optimizer can be mapped one-to-one with each Boost circuit, thereby achieving automatic networking of the optimizers connected to the photovoltaic system. This avoids the inefficiency and error-prone nature of manual input for optimizer networking. Furthermore, if an optimizer that is mistakenly connected due to crosstalk is not part of the photovoltaic system, the above steps will show that its output electrical parameters do not change with the short-circuit state of any input terminal of the inverter, thus eliminating the possibility of mistakenly connecting to an optimizer that is not part of the photovoltaic system due to crosstalk.

[0070] Based on the previous embodiment, preferably, the optimizer networking method of the photovoltaic system is as follows: Figure 2 As shown, before step S101, where the inverter sets the output voltage limit value and / or output current limit value for each optimizer, the following is also included:

[0071] S200, the inverter obtains the sequence number of the optimizer in each photovoltaic string.

[0072] The serial number refers to the SN number, or serialno, which is a unique code for each optimizer. Once the inverter obtains the serial number of each optimizer, it can distinguish between the optimizers.

[0073] In practical applications, when the inverter master node is powered on, it will actively search for optimizers, that is, send search commands to each optimizer. After the optimizer receives the search command from the inverter, it will send its own serial number to the inverter master node.

[0074] Furthermore, after step S104, the topology location information of each optimizer can be marked according to each sequence number, and the automatic networking result for the connected optimizer can be generated.

[0075] S201, The inverter determines whether it has received manually entered topology location information.

[0076] If no topology location information is received, proceed to step S101; if topology location information is received, proceed to step S202.

[0077] S202, The inverter determines whether each serial number matches the topology location information.

[0078] If the sequence numbers do not match the topology location information, proceed to step S101.

[0079] That is, after the inverter obtains the serial number of the optimizer in each photovoltaic string in step S200, if the inverter master node itself does not receive the manually entered topology location information sent by the cloud, or if the serial number of each optimizer found is inconsistent with the topology location information, it will enter the subsequent automatic networking process.

[0080] This embodiment provides the start-up triggering conditions for the automatic networking process in practical applications. If the start-up triggering conditions are not met, automatic networking can be skipped, allowing the networking process after inverter installation to be determined according to the actual situation, thus broadening its application scenarios.

[0081] In practical applications, the triggering condition can also be that the inverter master node directly sends a network mode setting command to each optimizer. In this case, the optimizer networking method of the photovoltaic system can directly execute step S101. Depending on the specific application environment, all of these are within the protection scope of this application.

[0082] Based on the above embodiments, if the output voltage limit value Ulmt has been set for each inverter in step S101, then preferably, the optimizer networking method of the photovoltaic system is as follows: Figure 3 (in order to be in) Figure 2 As shown in the example below, before step S103, where the inverter controls the corresponding Boost circuit input terminals to maintain a short-circuit state for a preset duration according to preset rules, it may further include:

[0083] S301. The inverter determines whether both ends of each photovoltaic string are connected in series with the output terminals of the corresponding optimizer based on the changes in the voltage at the input terminals of each Boost circuit before and after the start of each optimizer.

[0084] If both ends of each photovoltaic string are connected in series with the output of the corresponding optimizer, then step S103 is executed.

[0085] This requires that during optimizer startup in step S102, while the optimizer is still in the 1V output safety mode, the inverter master node must first read and record the voltage at each input terminal of the inverter. Then, the inverter master node controls the optimizer to start, ensuring the optimizer's output voltage reaches the output voltage limit value Ulmt. Once all optimizers have started, the inverter master node will again read and record the voltage at each input terminal of the inverter.

[0086] Then, the inverter master node can calculate based on the sampled and stored values ​​of the voltages before and after each optimizer starts, confirming that the photovoltaic strings connected to each input terminal of the inverter are photovoltaic strings in which all photovoltaic modules are equipped with the corresponding optimizers, and then continue to execute the subsequent short-circuit control steps for the Boost circuit, thereby realizing the automatic networking process.

[0087] For example, if the optimizer outputs 1V in safe mode and the output voltage limit Ulm = 10V in operating mode, and the voltage at a certain input terminal of the inverter is nV in the optimizer's safe mode but 10nV in the optimizer's operating mode, it means that the photovoltaic string connected to this input terminal is obtained by n optimizers connected in series through the output terminal. If all input terminals of the inverter are in this situation, it means that the photovoltaic system is a system in which each photovoltaic module is equipped with a corresponding optimizer, and the above-mentioned automatic networking process for optimizers can be performed.

[0088] Meanwhile, for photovoltaic systems that should all be equipped with optimizers, it is also possible to check whether each optimizer is properly connected and whether it can work normally. If, through the above calculations, it is found that the two sampled and stored values ​​of a certain input voltage of the inverter do not show the above correspondence, the subsequent steps of automatic networking will not be executed, and a corresponding alarm signal will be output to remind the operator to check the equipment condition and installation status of each optimizer connected to the corresponding input terminal of the inverter. After all optimizers are properly connected and working normally, the automatic networking process will be carried out to ensure the correctness of the networking results.

[0089] In addition, after step S301, if both ends of each photovoltaic string are connected in series with the output terminals of the corresponding optimizers, the inverter can determine the number of optimizers in the corresponding photovoltaic string based on the voltage at the input terminals of each Boost circuit.

[0090] Furthermore, by using the voltage read above and the output voltage limit value Ulm, the number of optimizers in the photovoltaic string connected to each Boost circuit can be determined for subsequent control.

[0091] It is worth noting that in the above-described short-circuit control steps for the Boost circuit, if the Boost circuit's drive module is powered by the DC bus between the Boost circuit and the inverter circuit, the voltage of the DC bus will drop when the Boost circuit is in a short-circuit state due to the power consumption of the drive module. Therefore, to prevent the drive module's drive signal from being interrupted due to excessively low DC bus voltage during the Boost circuit short-circuit control process, a minimum threshold Ulowthd can be pre-set for the DC bus voltage. Before controlling the Boost circuit to short-circuit, the DC bus voltage is checked. If the DC bus voltage is lower than the minimum threshold Ulowthd, the Boost circuit can be controlled to charge the DC bus first. When the DC bus voltage is charged to the minimum threshold Ulowthd, the short-circuit control for the Boost circuit is then executed.

[0092] That is, based on the above embodiments, the preferred method for optimizing the grid of the photovoltaic system is as follows: Figure 4 (in order to be in) Figure 2 As shown in the example below, before step S103, where the inverter controls the corresponding Boost circuit input terminals to maintain a short-circuit state for a preset duration according to preset rules, the following further steps are included:

[0093] S401, The inverter determines whether the voltage of the DC bus is lower than the preset minimum threshold.

[0094] If the DC bus voltage is lower than the preset minimum threshold (i.e., the aforementioned minimum threshold Ulowthd), then step S402 is executed. If the DC bus voltage is not lower than the preset minimum threshold, then step S103 is executed directly.

[0095] S402, The inverter controls at least one Boost circuit to charge the DC bus.

[0096] When the voltage of the DC bus reaches the preset minimum threshold, step S103 is executed.

[0097] This embodiment can ensure the complete execution of step S103 and avoid the problem of the drive module stopping due to loss of power during its execution.

[0098] The following is based on Figure 3 For example, the process of automatically networking a photovoltaic system with all installed optimizers using the above-mentioned optimizer networking method is illustrated below:

[0099] (1) The execution of this automatic networking process has certain triggering conditions.

[0100] After the inverter master node is powered on, it will actively search for the optimizer. Once the optimizer receives the search command from the inverter, it will send its own serial number to the inverter master node. If the inverter master node does not receive the manually entered topology location information sent from the cloud, or if the serial number of the found optimizer does not match the topology location information, it will enter the automatic networking process.

[0101] (2) The automatic networking process first involves setting the output electrical parameters of the optimizer.

[0102] Immediately after installation, when the photovoltaic modules connected to its input terminal can provide its normal operating voltage, the optimizer will enter a safe mode or shutdown mode, at which point its output voltage is 1V. The inverter master node sends a network mode setting command to each optimizer, which includes the output voltage limit value Ulmt and the output current limit value Ilmt.

[0103] (3) Then you can execute the steps to start the optimizer during the automatic networking process.

[0104] Before startup, the optimizer remains in a safe mode with an output voltage of 1V. The inverter master node reads and records the voltage at each input terminal of the inverter at this time. Then, the inverter master node broadcasts an activation command. Upon receiving this activation command, the optimizer switches to operating mode, begins a soft start, and gradually increases the output voltage until it reaches the output voltage limit value Ulmt. After all optimizers have started, the inverter master node reads and records the voltage at each input terminal of the inverter again.

[0105] Then, the inverter master node will calculate based on the sampled and stored values ​​of the voltages before and after each optimizer starts, to confirm that the photovoltaic strings connected to each input terminal of the inverter are all strings with optimizers installed.

[0106] (4) Then execute the short-circuit control steps for the input terminals of each Boost circuit during the automatic networking process.

[0107] In this step, the inverter master node sequentially selects one of the Boost circuits according to a preset order, gradually reducing its input voltage to near 0V, creating a short circuit, and maintaining this state for a period of Tshort. The rate of voltage decrease and the short-circuit holding time Tshort can be set according to actual needs and are not fixed here. After the holding time Tshort ends, the control state of that Boost circuit is canceled, and its input voltage is restored. Then, control is initiated on the next Boost circuit until all Boost circuits meeting the conditions have completed the above control process.

[0108] In the short-circuit control step for each Boost circuit input, when each Boost circuit's input is short-circuited, the inverter master node needs to collect the output voltage and current status of all optimizers at this time. Since an output current limit value Ilmt has been set for the optimizers, the optimizers connected to the Boost circuit input will operate with an output voltage of 0V and an output current limit value Ilmt; while optimizers not connected to the Boost circuit input will maintain an output voltage limit value Ulmt and an output current of 0A. Based on these differences in status, all optimizers connected to the Boost circuit input can be identified.

[0109] This embodiment applies to the automated grid-building process of all photovoltaic systems with optimizers installed. It can automatically identify the optimizer connected to the input of each Boost circuit and eliminate optimizers found due to crosstalk, thus automatically networking the optimizers connected to the system. This avoids the need for manual input of each optimizer's information, improving networking efficiency and reducing the probability of errors.

[0110] Another embodiment of this application also provides a photovoltaic system, which, as shown in the example below... Figure 5 As shown, it includes: an inverter 200 and at least one photovoltaic string 100; wherein:

[0111] The inverter 200 has at least one Boost circuit 201 at the front end of the DC bus, and the input terminal of each Boost circuit 201 is used to connect at least one corresponding photovoltaic string 100.

[0112] It is worth noting that, such as Figure 5 As shown, each Boost circuit 201 can be integrated into the inverter 200, and the output terminal of each Boost circuit 201 is connected to the DC side of the inverter circuit 202 in the inverter 200 via a DC bus. In practical applications, each Boost circuit 201 can also be independent of the inverter 200 (not shown), depending on the specific application environment, and all are within the protection scope of this application.

[0113] Depending on the model, the inverter 200 is connected to the corresponding applicable single-phase or three-phase power grid.

[0114] like Figure 6 As shown, an optimizer 102 with one or at least two output terminals connected in series is provided between the two ends of the photovoltaic string 100, and the input terminal of the optimizer 102 is connected to at least one photovoltaic module 101.

[0115] The controller in inverter 200, acting as the inverter master node as described in the above embodiments, communicates with each optimizer 102 and is used to execute the optimizer networking method of the photovoltaic system as described in any of the above embodiments. The specific execution process and principle of this optimizer networking method can be found in the above embodiments and will not be repeated here.

[0116] like Figure 5 and Figure 7 As shown, when the main circuit of the inverter 200 includes an inverter circuit 202 and at least one Boost circuit 201, the inverter 200 can contain m Boost circuits (e.g., ...). Figure 7 The Boost 1 to Boost m shown are positive integers greater than or equal to 1.

[0117] In practical applications, the input terminals of each Boost circuit 201 can be connected to only one connection port on the DC side of the inverter 200, or they can be connected to at least two parallel connection ports on the DC side of the inverter 200. The settings of the input terminals of each Boost circuit 201 can be the same or different, depending on the specific application environment, and all are within the protection scope of this application. The connection ports connected to the input terminals of each Boost circuit 201 can be connected to one photovoltaic string 100, or at least two photovoltaic strings 100 can be connected in parallel through a bus terminal; depending on the specific application environment, all are within the protection scope of this application.

[0118] Specifically, each Boost circuit 201 has one input terminal, which can also be called an MPPT port. Each MPPT port can be divided into two parallel connection ports inside the inverter 200, which can be called PV ports. Of course, each MPPT port can also directly become a PV port. Each PV port can connect to one photovoltaic string 100, or connect two parallel photovoltaic strings 100 through a bus terminal. A system can connect at least one photovoltaic string 100.

[0119] See Figure 6 and Figure 7 Assume each photovoltaic string 100 includes n photovoltaic modules (PV modules 1 to n as shown in the figure), where n is a positive integer greater than or equal to 2. When the inverter 200 is a single-camera system, n is less than or equal to 25; when the inverter 200 is a three-camera system, n is less than or equal to 50. Since the system is entirely equipped with optimizers 102, each photovoltaic module must include one photovoltaic unit and one optimizer 102. The photovoltaic unit includes at least one photovoltaic module 101, which is connected to the input of the optimizer 102. The outputs of all optimizers 102 in the photovoltaic string 100 are connected in series; that is, the positive output of optimizer 102 is connected to the negative output of the previous optimizer 102, the negative output of optimizer 102 is connected to the positive output of the next optimizer 102, and finally connected to a PV port of the inverter 200.

[0120] It should be noted that the number of photovoltaic modules in different photovoltaic strings 100 connected to the same system may vary, the series and parallel connection methods of photovoltaic strings 100 connected to different MPPT ports may be inconsistent, and the power of photovoltaic units may be inconsistent.

[0121] In practical applications, see Figure 7k photovoltaic strings (as shown in the figure, photovoltaic strings 1 to k) 100 are connected to m Boost circuits 201 of an inverter 200. Each Boost circuit 201 may or may not have photovoltaic strings 100 connected to its MPPT port, or it may have 1 to 3 photovoltaic strings 100 connected, depending on the specific application environment. All of these are within the scope of protection of this application.

[0122] Similar or identical parts between the various embodiments in this specification can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and relevant parts can be referred to the description of the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment solution according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0123] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0124] The features described above regarding the disclosed embodiments can be substituted for or combined with each other to enable those skilled in the art to implement or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for optimizing the grid of a photovoltaic system, characterized in that, The photovoltaic system includes: an inverter and corresponding photovoltaic strings connected to each Boost circuit in the DC bus front stage; each photovoltaic string includes an optimizer connected to a photovoltaic module; the optimizer networking method includes: The inverter sets output voltage limit values ​​and / or output current limit values ​​for each of the optimizers; The inverter controls the startup of each of the optimizers; The inverter controls the corresponding Boost circuit input terminals to maintain a short-circuit state for a preset duration according to preset rules; The inverter determines the optimizer connected to the input terminal of each Boost circuit based on the output electrical parameters of all optimizers under each short-circuit state.

2. The photovoltaic system optimizer networking method according to claim 1, characterized in that, The inverter controls the corresponding Boost circuit input terminals to maintain a short-circuit state for a preset duration according to preset rules, including: The inverter controls each Boost circuit input to maintain a short-circuit state for a preset duration; or... The inverter groups all Boost circuits sequentially, and each time controls some of the Boost circuit input terminals in the current group to remain in a short-circuit state for a preset time. The current group is then grouped again according to the different states of the Boost circuit input terminals until the current group contains only one Boost circuit.

3. The photovoltaic system optimizer networking method according to claim 1, characterized in that, The output electrical parameters include: output voltage, and / or, output current.

4. The photovoltaic system optimizer networking method according to claim 3, characterized in that, The inverter determines the optimizer connected to the input of each Boost circuit based on the output electrical parameters of all optimizers under each short-circuit state, including: In each short-circuit state, for each optimizer whose output voltage is zero and / or whose output current is greater than a preset current value or is the output current limit value, the inverter determines that it is connected to the Boost circuit in the input short-circuit state; for each optimizer whose output voltage is not zero and / or whose output current is zero, the inverter determines that it is not connected to the Boost circuit in the input short-circuit state.

5. The photovoltaic system optimizer networking method according to any one of claims 1 to 4, characterized in that, Before the inverter sets the output voltage limit value and / or output current limit value for each of the optimizers, the method further includes: The inverter obtains the sequence number of the optimizer in each of the photovoltaic strings; The inverter determines whether it has received manually entered topology location information; If the topology location information is not received, the inverter performs the step of setting the output voltage limit value and / or output current limit value for each of the optimizers; If the topology location information is received, the inverter determines whether each of the serial numbers matches the topology location information; If the serial number does not match the topology location information, the inverter will perform the step of setting the output voltage limit value and / or output current limit value for each of the optimizers.

6. The optimizer networking method for a photovoltaic system according to any one of claims 1 to 4, characterized in that, If the inverter has already set the output voltage limit value for each of the optimizers, then after the inverter controls each of the optimizers to start, the method further includes: Control the output voltage of each optimizer to reach the output voltage limit value; Furthermore, before the inverter controls the corresponding Boost circuit input terminals to maintain a short-circuit state for a preset duration according to preset rules, the following steps are also included: The inverter determines whether both ends of each photovoltaic string are connected in series by the output terminals of the corresponding optimizer based on the change in voltage at the input terminals of each Boost circuit before and after the start of each optimizer. If so, the inverter determines the number of optimizers in the corresponding photovoltaic string based on the voltage at the input terminal of each Boost circuit, and executes the step of the inverter controlling the input terminals of the corresponding Boost circuits to maintain a short-circuit state for a preset duration according to preset rules.

7. The photovoltaic system optimizer networking method according to any one of claims 1 to 4, characterized in that, Before the inverter controls the corresponding Boost circuit input terminals to maintain a short-circuit state for a preset duration according to preset rules, the following steps are included: The inverter determines whether the voltage of the DC bus is lower than a preset minimum threshold. If the voltage of the DC bus is lower than the preset minimum threshold, the inverter controls at least one Boost circuit to charge the DC bus. When the voltage of the DC bus reaches the preset minimum threshold, the inverter executes the step of controlling the corresponding Boost circuit input terminals to maintain a short-circuit state for a preset duration according to preset rules.

8. The optimizer networking method for a photovoltaic system according to any one of claims 1 to 4, characterized in that, The inverter controls the startup of each of the optimizers, including: The inverter sends activation commands to each of the optimizers, causing each optimizer to enter the working mode and increase the output voltage through soft start.

9. A photovoltaic system, characterized in that, include: Inverter and at least one photovoltaic string; One or at least two optimizers with their outputs connected in series are provided between the two ends of the photovoltaic string, and the input of the optimizer is connected to at least one photovoltaic module. The inverter is equipped with at least one Boost circuit in the front stage of the DC bus, and the input terminal of each Boost circuit is used to connect at least one corresponding photovoltaic string. The controller in the inverter acts as a master node, communicates with each of the optimizers, and is used to execute the optimizer networking method of the photovoltaic system as described in any one of claims 1 to 8.

10. The photovoltaic system according to claim 9, characterized in that, Each Boost circuit is independent of the inverter; or, Each Boost circuit is integrated into the inverter, and the output of each Boost circuit is connected to the DC side of the inverter circuit in the inverter through the DC bus.

11. The photovoltaic system according to claim 9 or 10, characterized in that, Each Boost circuit is integrated into the inverter. Inside the inverter, the input terminal of each Boost circuit is connected to one connection port on the DC side of the inverter, or at least two connection ports connected in parallel. The connection port connects to one of the photovoltaic strings, or the connection port connects to at least two of the photovoltaic strings in parallel via a bus terminal.

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