A photovoltaic system and a method for network updating of its optimizer

Abstract

This application provides a photovoltaic system and its optimizer network update method. The optimizer network update method first involves the inverter acquiring the serial number of the optimizer in each photovoltaic string at a preset time and determining whether the optimizer corresponding to each serial number has completed network configuration. If at least one optimizer has not completed network configuration, it indicates that it is a replaced or newly added optimizer. In this case, the inverter controls or maintains the operation of the optimizedrs that have completed network configuration and actively bypasses the optimizedrs that have not completed network configuration. Then, the inverter compares the output current of each optimizedr that has not completed network configuration with the current of each photovoltaic string to determine the photovoltaic string to which each optimizedr belongs. This achieves automatic network update for replaced or added optimizers without manual input, avoiding the increased number of manual maintenance operations and wasted time.

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 grid-connected update 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] Currently, the topology location information of each optimizer is usually manually entered in sequence after the system is installed. However, during the actual operation of the photovoltaic system, problems such as optimizer damage and photovoltaic string expansion may occur, which require the replacement or addition of new optimizers. If the manual entry process is performed every time an optimizer is replaced or added, it increases the number of manual maintenance operations and wastes time. Summary of the Invention

[0005] In view of this, this application provides a method for updating the network topology of a photovoltaic system and its optimizer, so as to avoid the problem of increased manual maintenance and wasted time caused by manual data entry for updating the optimizer network topology.

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

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

[0008] The inverter acquires the sequence number of the optimizer in each photovoltaic string at a preset time.

[0009] The inverter determines whether the optimizer corresponding to each of the serial numbers has completed the network formation;

[0010] If at least one of the optimizers has not completed networking, the inverter controls or keeps the optimizers that have completed networking running, and controls the optimizers that have not completed networking to actively bypass.

[0011] The inverter compares the output current of each optimizer that has not yet completed networking with the current of each photovoltaic string to determine the photovoltaic string to which each optimizer that has not yet completed networking belongs.

[0012] Optionally, the inverter determines whether the optimizer corresponding to each of the sequence numbers has completed network formation, including:

[0013] The inverter determines whether each of the serial numbers has been stored by itself;

[0014] For the stored serial number, the inverter determines that it has completed network formation;

[0015] If the serial number has not been stored, the inverter determines that the network has not been completed.

[0016] Optionally, the inverter controls or keeps the optimizer running after the network has been completed, including:

[0017] If the inverter is in operation, the inverter will maintain the operation of the optimizer that has completed the network setup;

[0018] If the inverter is not in operation, the inverter controls the optimizer, which has completed the network setup, to start and run.

[0019] Optionally, controlling the optimizer to actively bypass when the network formation is incomplete includes:

[0020] In sequence or simultaneously, an active bypass command is sent to the optimizers that have not completed networking, causing the corresponding optimizers to switch their state to the active bypass state.

[0021] Optionally, the inverter compares the output current of each optimizer that has not yet completed grid connection with the current of each photovoltaic string to determine the photovoltaic string to which each optimizer that has not yet completed grid connection belongs, including:

[0022] The inverter determines the deviation between the output current of each unconnected optimizer and the current of each photovoltaic string;

[0023] The inverter determines that the optimizer whose corresponding deviation is less than or equal to the preset difference belongs to the corresponding photovoltaic string.

[0024] Optionally, after determining that at least one of the optimizers has not completed network formation, the method further includes:

[0025] The inverter determines whether the number of optimizers that have not completed networking is less than a preset number;

[0026] If so, then execute the steps of controlling the inverter or keeping the optimizer that has completed networking running, and controlling the optimizer that has not completed networking to actively bypass;

[0027] Otherwise, the inverter first sets the output voltage limit value and / or output current limit value for each of the optimizers, and then controls each of the optimizers to start; then the inverter controls the input terminals of the corresponding Boost circuits to maintain a short circuit state for a preset duration according to preset rules, and determines the optimizer connected to each Boost circuit according to the output electrical parameters of all the optimizers under each short circuit state, and marks the topology location information of each optimizer according to each of the serial numbers, thus completing the networking of each optimizer.

[0028] Optionally, the output electrical parameters include: output voltage, and / or, output current;

[0029] The inverter determines the optimizer connected to each Boost circuit based on the output electrical parameters of all optimizers under each short-circuit state, including:

[0030] 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.

[0031] 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:

[0032] The inverter controls each Boost circuit input to maintain a short-circuit state for a preset duration; or...

[0033] 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.

[0034] Optionally, after determining the optimizer connected to each Boost circuit, the method further includes:

[0035] The inverter determines whether the electrical states of each optimizer in the parallel photovoltaic string connected to the Boost circuit are consistent.

[0036] If all the electrical states are consistent, then the corresponding parallel photovoltaic string is determined to be a parallel photovoltaic string with no voltage difference.

[0037] If the electrical states are not consistent, the inverter first determines that the optimizer whose output current is greater than the preset positive current value or less than the preset negative current value belongs to the same photovoltaic string; then, if the number of photovoltaic strings in the corresponding parallel photovoltaic strings is greater than 2, it determines that the other photovoltaic strings are the parallel no-voltage photovoltaic strings.

[0038] For the parallel photovoltaic strings with no voltage drop, the inverter controls one of the optimizers to change its output voltage at least once, and distinguishes the photovoltaic strings to which each optimizer belongs based on the electrical state of each optimizer under each control.

[0039] Optionally, the output voltage can be changed, including: active bypass; or,

[0040] If the inverter has 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: the inverter controlling the output voltage of each of the optimizers to reach the output voltage limit value; and changing the output voltage, including: increasing or decreasing the output voltage limit value.

[0041] Optionally, the electrical state includes at least one of output voltage, output current, and operating state;

[0042] The photovoltaic strings to which each optimizer belongs are distinguished by the electrical state of each optimizer under each control, including:

[0043] If the direction of changing the output voltage is to decrease, then the optimizer that satisfies at least one of the following conditions: the output voltage is the output voltage limit value, the output current is the negative output current limit value, and the operating state is the reverse input state, is in the same photovoltaic string as the optimizer that changes the output voltage.

[0044] If the direction of the output voltage is changed to increase, then the optimizer that satisfies at least one of the following conditions: the output voltage is less than the output voltage limit, the output current is positive, and the operating state is positive output state, is in the same photovoltaic string as the optimizer that changes the output voltage.

[0045] In addition, other optimizers are identified as belonging to other photovoltaic strings.

[0046] Optionally, after comparing the output current of each unconnected optimizer with the current of each photovoltaic string, the inverter further includes:

[0047] If the current deviation of at least two photovoltaic strings is within a preset range, the inverter controls the input voltage of each Boost circuit one by one, so that each circuit changes at least once.

[0048] After each voltage change, the inverter performs a step of comparing the output current of each unconnected optimizer with the current of each photovoltaic string, until the photovoltaic string to which each unconnected optimizer belongs is determined.

[0049] Optionally, after each voltage change, the inverter performs a step of comparing the output current of each unconnected optimizer with the current of each photovoltaic string. Afterwards, the process further includes:

[0050] If at least one of the optimizers has not completed networking and its output current does not match the current of all photovoltaic strings, it is determined that it does not belong to the photovoltaic system.

[0051] A second aspect of this application also provides a photovoltaic system, comprising: an inverter and at least one photovoltaic string;

[0052] 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.

[0053] 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.

[0054] The controller in the inverter acts as a master node, communicates with each of the optimizers, and is used to execute the optimizer networking update method for the photovoltaic system as described in any of the first aspects above.

[0055] Optionally, each Boost circuit is independent of the inverter; or,

[0056] 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.

[0057] Optionally, the input terminal of the Boost circuit is connected to one connection port on the DC side of the inverter, or at least two connection ports connected in parallel.

[0058] 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.

[0059] The photovoltaic system optimizer networking update method provided in this application firstly involves the inverter acquiring the serial number of the optimizer in each photovoltaic string at a preset time and determining whether the optimizer corresponding to each serial number has completed networking. If at least one optimizer has not completed networking, it indicates that it is a replaced or newly added optimizer. In this case, the inverter controls or keeps the optimizedrs that have completed networking running and actively bypasses the optimizedrs that have not completed networking. Then, the inverter compares the output current of each optimizedr that has not completed networking with the current of each photovoltaic string to determine the photovoltaic string to which each optimizedr belongs. This achieves automatic networking update for replaced or added optimizers without the need for manual data entry, avoiding the problems of increased manual maintenance and wasted time. Attached Figure Description

[0060] 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.

[0061] Figures 1 to 4 Four flowcharts are provided for the optimizer network update method of the photovoltaic system provided in the embodiments of this application;

[0062] Figure 5 This is a schematic diagram of the structure of a photovoltaic system provided in an embodiment of this application;

[0063] Figure 6 This is a schematic diagram of the structure of a photovoltaic string provided in an embodiment of this application;

[0064] Figure 7 This is a schematic diagram of the specific structure of the photovoltaic system provided in the embodiments of this application. Detailed Implementation

[0065] 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.

[0066] 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.

[0067] This application provides a method for updating the optimizer network of a photovoltaic system, thereby avoiding the problems of increased manual maintenance and wasted time caused by manual data entry for updating the optimizer network.

[0068] The photovoltaic system includes: an inverter, and the corresponding photovoltaic strings connected to each Boost circuit in the DC bus front-end of the inverter; see [link to relevant documentation]. Figure 1 The optimizer network update method for this photovoltaic system includes:

[0069] S101, The inverter obtains the sequence number of the optimizer in each photovoltaic string at a preset time.

[0070] 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.

[0071] The preset time includes: the corresponding moment after power-on, and the corresponding moment every subsequent preset cycle.

[0072] In practical applications, when the inverter reaches the corresponding time mentioned above, it will actively search for the optimizer, that is, send a search command to each optimizer. After receiving the search command from the inverter, the optimizer will send its own serial number to the inverter.

[0073] S102. The inverter determines whether the optimizer corresponding to each serial number has completed the network formation.

[0074] After the system is installed, each optimizer connected to the inverter will be networked. However, if optimizers are replaced or added during subsequent applications, i.e., when a new optimizer is connected to the inverter, its serial number can be used to identify that the new optimizer has not yet been networked. Specifically, the inverter can determine whether each serial number has been stored by itself. For serial numbers that have been stored, the inverter determines that the network has been completed; for serial numbers that have not been stored, the inverter determines that the network has not been completed.

[0075] If at least one optimizer has not completed networking, it indicates that it is a replaced or newly added optimizer. In this case, the inverter cannot perform command control and status positioning on it. Therefore, step S103 needs to be executed.

[0076] S103, The inverter controls or keeps the optimizer that has completed networking running, and controls the optimizer that has not completed networking to actively bypass.

[0077] For optimizers that have completed network connectivity, the inverter can perform command control and status positioning, thus ensuring they are always in operation. Specifically, if the inverter is in operation, including grid-connected operation and off-grid operation with load, as long as the inverter has power or current output, it can maintain the operation of the optimized optimizers that have completed network connectivity. If the inverter is not in operation, the inverter controls the optimized optimizers that have completed network connectivity to start and run, and then the inverter operates normally in grid-connected mode, outputting power.

[0078] For optimizers that have not completed network setup, in order to avoid errors in the inverter's judgment and control, the inverter may not send activation commands to them, or because newly installed optimizers have not been set by certain commands, they may automatically not start running.

[0079] Furthermore, the inverter can send active bypass commands sequentially or simultaneously to newly installed optimizers it has searched for, i.e., optimizers that have not yet completed network connection; after receiving the active bypass command, the newly installed optimizer switches its state to the active bypass state. At this time, the current of the photovoltaic string in which it is located will flow through the output of the optimizer, and the amplitude of the current can be sampled and detected, and the process proceeds to step S104.

[0080] S104. The inverter compares the output current of each optimizer that has not yet completed networking with the current of each photovoltaic string to determine the photovoltaic string to which each optimizer that has not yet completed networking belongs.

[0081] The inverter can obtain the output current of each optimizer through communication; the inverter can also obtain the current of each photovoltaic string through direct sampling; for two currents with the same current value, the correspondence between their respective owners can be determined, and thus the photovoltaic string to which each optimizer belongs can be identified.

[0082] In practical applications, considering the impact of sampling accuracy and communication interference, a certain margin can be set for the comparison between the two currents. That is, the inverter can first determine the deviation between the output current of each unconnected optimizer and the current of each photovoltaic string; then, it can determine the optimizer whose deviation is less than or equal to the preset difference value and belongs to the corresponding photovoltaic string. In practical applications, this preset difference value can be 1A, but it is not limited to this and depends on the application environment, all of which are within the protection scope of this application.

[0083] The photovoltaic system optimizer network update method provided in this embodiment improves upon the above principle and can achieve automatic network update for replacing or adding optimizers without manual input, thus avoiding the problems of increased manual maintenance and wasted time.

[0084] It is worth noting that in the previous embodiment, after determining that at least one optimizer has not completed network deployment, the inverter can first determine the number of these incomplete optimizers. If the number is large, even controlling the normal operation of other optimizers may not guarantee the inverter's power generation and efficiency. Therefore, this embodiment, based on the previous embodiment, provides another method for updating the optimizer network of a photovoltaic system, as follows: Figure 2 As shown, after determining that at least one optimizer has not completed network formation, the process also includes:

[0085] S201. The inverter determines whether the number of optimizers that have not completed networking is less than the preset number.

[0086] The preset number can be 20% of the total number of optimizers in the photovoltaic system, but it is not limited to this. It depends on the specific application environment and is within the scope of protection of this application.

[0087] If so, then execute step S103: control or keep the optimizer that has completed networking running, and control the optimizer that has not completed networking to actively bypass.

[0088] Otherwise, proceed with steps S202 to S205.

[0089] S202, The inverter sets output voltage limit values ​​and / or output current limit values ​​for each optimizer.

[0090] When the photovoltaic modules connected to the input terminals of each optimizer can provide their normal operating voltage, the optimizer will enter a safe mode or a shutdown mode, at which time its output voltage is 1V. Then the inverter will send a grid mode setting command to each optimizer, which includes the output voltage limit value Ulmt and the output current limit value Ilmt. In practical applications, Ulmt can be set to 10V and Ilmt to 2A, but it is not limited to these.

[0091] S203, Inverter controls the startup of each optimizer.

[0092] In practical applications, the inverter can broadcast an activation command to each optimizer. Upon receiving the activation command, the optimizer will switch to the working mode, start a soft start, and gradually increase the output voltage until it reaches the output voltage limit value Ulmt. Alternatively, if the output voltage limit value Ulmt is not set, it will reach its rated output voltage.

[0093] S204. The inverter controls the corresponding Boost circuit input terminals to maintain a short-circuit state for a preset duration according to preset rules.

[0094] In practical applications, this step can be specifically as follows: the inverter controls each Boost circuit input terminal to maintain a short-circuit state for a preset duration; or, the inverter groups all Boost circuits sequentially, controls some Boost circuit input terminals in the current group to maintain a short-circuit state for a preset duration each time, and regroups the current group according to the different states of the Boost circuit input terminals, until the current group contains only one Boost circuit.

[0095] S205. The inverter determines the optimizer connected to each Boost circuit based on the output electrical parameters of all optimizers under each short-circuit state, and then marks the topology location information of each optimizer according to each serial number to complete the networking of each optimizer.

[0096] In practical applications, the output electrical parameters include: output voltage and / or output current. In step S205, the inverter determines the optimizer connected to each Boost circuit based on the output electrical parameters of all optimizers under each short-circuit state. Specifically, this may include: under each short-circuit state, for optimizers whose output voltage is zero and / or whose output current is greater than a preset current value or is at the output current limit value, the inverter determines that they are connected to the Boost circuit in the input short-circuit state; for optimizers whose output voltage is not zero and / or whose output current is zero, the inverter determines that they are not connected to the Boost circuit in the input short-circuit state.

[0097] Steps S202 to S205 can achieve unified renetworking for each optimizer. Moreover, when the system is installed and the inverter is powered on, and the optimizer serial number is searched for for the first time, before any optimizer has completed networking, steps S202 to S205 can also achieve automatic networking for each optimizer. This avoids the problems of low efficiency and easy error when networking optimizers through manual input in the prior art.

[0098] Moreover, in practical applications, if only a small number of optimizers are replaced or added, it may waste a lot of time to repeat the unified networking process of steps S202 to S205. Therefore, in this embodiment, the determination is made in step S201, and when the number of newly installed optimizers is small, the update of the optimizer networking can be achieved through steps S103 and S104 to avoid wasting time and enable the inverter to generate as much power as possible.

[0099] Furthermore, it's worth noting that when the number of photovoltaic strings connected to the Boost circuit is greater than one, if the inverter is unsure which optimizers are in the same string, it will affect its judgment of long strings, incorrectly issuing limiting values. This can cause the sum of the output voltages of all optimizers in the string to exceed the inverter's withstand voltage, leading to overvoltage damage. Therefore, in step S205 above, after the inverter determines which optimizers are connected to each Boost circuit, it can also include... Figure 3 As shown:

[0100] S301. The inverter determines whether the electrical states of each optimizer in the parallel photovoltaic string connected to the Boost circuit are consistent.

[0101] If all electrical states are consistent, the corresponding parallel photovoltaic string is determined to be a parallel photovoltaic string with no voltage difference, and step S302 is executed directly. If the electrical states are not consistent, step S303 is executed first, and then if the number of photovoltaic strings in the corresponding parallel photovoltaic string is greater than 2, the other photovoltaic strings are determined to be parallel photovoltaic strings with no voltage difference, and step S302 is executed.

[0102] S302. For parallel photovoltaic strings with no voltage difference, the inverter controls one of the optimizers to change the output voltage at least once, and distinguishes the photovoltaic strings to which each optimizer belongs by the electrical state of each optimizer under each control.

[0103] In practical applications, changing the output voltage includes: active bypass; or,

[0104] If the inverter has 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: the inverter controlling the output voltage of each of the optimizers to reach the output voltage limit value; and changing the output voltage, including: increasing or decreasing the output voltage limit value.

[0105] The electrical state includes at least one of output voltage, output current, and operating state. In step S302, the photovoltaic string to which each optimizer belongs is distinguished based on its electrical state under each control. Specifically, if the direction of changing the output voltage is decreasing, the optimizer that satisfies at least one of the following conditions is in the same photovoltaic string as the optimizer that changed the output voltage. If the direction of changing the output voltage is increasing, the optimizer that satisfies at least one of the following conditions is in the same photovoltaic string as the optimizer that changed the output voltage.

[0106] Step S302 allows the parallel photovoltaic strings to be divided into long strings and short strings, thereby forming a circulating current. Since the circulating current causes the electrical states of the optimizers in the long strings and short strings to be different, the electrical states of each optimizer can be used to distinguish the photovoltaic strings to which they belong. This automatically achieves the differentiation of optimizers between different photovoltaic strings connected to the Boost circuit, that is, it achieves string-level positioning of the optimizers.

[0107] S303, the inverter determines the optimizer whose output current is greater than the preset positive current value or less than the preset negative current value, and belongs to the same photovoltaic string.

[0108] If the electrical states of the optimizers in a parallel photovoltaic string are not consistent, it indicates that there is a photovoltaic string of a special length. If this photovoltaic string is longer than other photovoltaic strings, all the optimizers inside it will be in a positive output state, and its output current will be the positive output current limit value. If this photovoltaic string is shorter than other photovoltaic strings, all the optimizers inside it will be in a reverse input state, and its output current will be the negative output current limit value.

[0109] Step S303 can identify a photovoltaic string of a special length from the parallel photovoltaic strings. If the number of parallel photovoltaic strings is greater than 2, at least two photovoltaic strings will fail to achieve their own string-level positioning. In this case, step S302 can be used to actively create long strings and short strings, thereby achieving string-level positioning for all optimizers.

[0110] It should be noted that in practical applications, the current of multiple photovoltaic strings may be almost the same. Therefore, based on the above embodiments, the photovoltaic system optimizer networking update method provided in this embodiment, after step S104, uses the corresponding Boost circuit control as a multiple verification strategy to ensure that the photovoltaic string to which each optimizer that has not completed networking belongs can be determined.

[0111] For details, please refer to [link / reference]. Figure 4 (in order to be in) Figure 1 Taking this as an example, the optimizer network update method, after comparing the output current of each optimizer that has not completed network connection with the current of each photovoltaic string in step S104, also includes:

[0112] S401. Determine whether there are at least two photovoltaic strings whose current deviation is within the preset range.

[0113] If none exist, the photovoltaic string to which each unfinished optimizer belongs can be directly determined; if at least two photovoltaic strings have current deviations within a preset range, then step S402 is executed.

[0114] S402, the inverter controls the input voltage of each Boost circuit one by one, causing each to change at least once.

[0115] Specifically, the process may include: the inverter sequentially selecting a Boost circuit and controlling its input voltage to gradually decrease to at least one state.

[0116] S403. After each voltage change, the inverter performs a step of comparing the output current of each unconnected optimizer with the current of each photovoltaic string.

[0117] This process involves multiple verifications until the photovoltaic string to which each optimizer that has not completed networking belongs is determined. However, after multiple verifications, if at least one optimizer that has not completed networking has an output current that does not match the current of all photovoltaic strings, it can be determined that it does not belong to this photovoltaic system.

[0118] The automatic string location scheme for newly installed optimizers provided in this embodiment can automatically locate the photovoltaic string of a newly added optimizer in a system that has already been networked by performing steps such as optimizer search, optimizer active bypass and Boost circuit control, and making multiple matching judgments between the optimizer output current and the Boost circuit input current (i.e., the photovoltaic string current).

[0119] 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:

[0120] 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.

[0121] 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.

[0122] Depending on the model, the inverter 200 is connected to the corresponding applicable single-phase or three-phase power grid.

[0123] 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.

[0124] The controller in inverter 200, acting as the master node, communicates with each optimizer 102 and is used to execute the optimizer network update method for the photovoltaic system as described in any of the above embodiments. The specific execution process and principle of this optimizer network update method can be found in the above embodiments and will not be repeated here.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] See Figure 6 and Figure 7Assume 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.

[0129] 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.

[0130] In practical applications, see Figure 7 K photovoltaic (PV) strings (PV strings 1 to PV string k as shown in the figure) 100 are connected to m Boost circuits of an inverter 200. Each Boost circuit's MPPT port may or may not be connected to any PV string 100, or it may be connected to one to three PV strings 100, depending on the specific application environment; all of these are within the scope of this application. Among these PV strings, t optimizers are newly installed optimizers, unevenly distributed among these k PV strings.

[0131] The main steps of this optimizer network update method are explained below:

[0132] (1) Optimizer search steps.

[0133] The optimizer search step mainly includes steps S101 and S102 as described in the above embodiments. In this optimizer search step, the inverter master node actively searches for optimizer information upon first power-on and at fixed intervals. When an optimizer that has not been networked receives a search command from the inverter, it sends its own serial number to the inverter master node. When the inverter master node finds optimizer information that has not been previously stored, it is considered to have discovered a newly installed optimizer.

[0134] The optimizer search step can further include step S201 as described in the above embodiment. That is, after a newly installed optimizer is discovered, the inverter can make a judgment. If the number of newly installed optimizers is small, less than a certain preset value (i.e., the preset number), or if the inverter is currently operating in grid-connected mode, the automatic positioning scheme can be triggered. If the inverter is not currently operating in grid-connected mode, the inverter master node will first start the existing optimizers that have already completed the network connection, and then the inverter will operate normally in grid-connected mode, outputting power. For newly installed optimizers, the inverter master node may not send activation commands to them, or because the newly installed optimizers have not been set by certain commands, they will automatically not start operating.

[0135] (2) Optimizer bypass step.

[0136] The optimizer bypass step mainly includes step S103 in the above embodiment, which controls the optimizer that has not completed networking to actively bypass, and step S104.

[0137] Specifically, the inverter master node will send active bypass commands to the newly installed optimizers sequentially or simultaneously. After receiving the active bypass command, the newly installed optimizer will switch its state to active bypass state. At this time, the optimizer's output will have the current of its own photovoltaic string operating normally flowing through it, and the amplitude of this current can be sampled and detected.

[0138] When a new optimizer is actively bypassed, the inverter master node reads the output current of the newly installed optimizer and the current of each photovoltaic string connected to the inverter, and compares them. If the deviation between the output current of the newly installed optimizer and the current of one of the photovoltaic strings is less than a pre-set threshold (i.e., the aforementioned preset difference), then the newly installed optimizer can be determined to belong to that photovoltaic string. However, since it is possible for the currents of multiple photovoltaic strings to be almost identical, a corresponding boost circuit control is required as a multiple verification strategy.

[0139] (3) Boost circuit control steps.

[0140] This step mainly includes step S402 as described in the above embodiment. The inverter master node can sequentially and individually control the MPPT port voltage of the inverter, causing the current of each photovoltaic string to change accordingly. For the same MPPT port, its voltage can be changed multiple times. After each stabilization, the inverter master node will read the output current of all newly installed optimizers and the current of each photovoltaic string in the inverter, and compare them. If the deviation between the output current of the newly installed optimizer and the current of a certain photovoltaic string is less than a pre-set threshold (i.e., the aforementioned preset difference), and after multiple changes and verifications, it can be determined that the newly installed optimizer belongs to that photovoltaic string.

[0141] In addition, if a newly installed optimizer does not match the MPPT port of any Boost circuit after multiple verifications, it is considered not to be in the photovoltaic system.

[0142] Through the above process, newly installed optimizers in photovoltaic systems that have already been networked can be automatically located to their respective photovoltaic strings. This avoids the need for manual input of information for each optimizer, improving network efficiency and reducing the probability of errors.

[0143] 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.

[0144] 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.

[0145] 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 updating the optimizer network in 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 network update method includes: The inverter acquires the sequence number of the optimizer in each photovoltaic string at a preset time. The inverter determines whether the optimizer corresponding to each of the serial numbers has completed the network formation; If at least one of the optimizers has not completed networking, the inverter controls or keeps the optimizers that have completed networking running, and controls the optimizers that have not completed networking to actively bypass. The inverter compares the output current of each optimizer that has not yet completed networking with the current of each photovoltaic string to determine the photovoltaic string to which each optimizer that has not yet completed networking belongs.

2. The photovoltaic system optimizer network update method according to claim 1, characterized in that, The inverter determines whether the optimizer corresponding to each of the serial numbers has completed network formation, including: The inverter determines whether each of the serial numbers has been stored by itself; For the stored serial number, the inverter determines that it has completed network formation; If the serial number has not been stored, the inverter determines that the network has not been completed.

3. The photovoltaic system optimizer network update method according to claim 1, characterized in that, The inverter controls or keeps the optimizer running after the network has been completed, including: If the inverter is in operation, the inverter will maintain the operation of the optimizer that has completed the network setup; If the inverter is not in operation, the inverter controls the optimizer, which has completed the network setup, to start and run.

4. The photovoltaic system optimizer network update method according to claim 1, characterized in that, Controlling the active bypass of the optimizer when the network is not yet fully formed includes: In sequence or simultaneously, an active bypass command is sent to the optimizers that have not completed networking, causing the corresponding optimizers to switch their state to the active bypass state.

5. The photovoltaic system optimizer network update method according to claim 1, characterized in that, The inverter compares the output current of each optimizer that has not yet completed grid connection with the current of each photovoltaic string to determine the photovoltaic string to which each optimizer that has not yet completed grid connection belongs, including: The inverter determines the deviation between the output current of each unconnected optimizer and the current of each photovoltaic string; The inverter determines that the optimizer whose corresponding deviation is less than or equal to a preset difference belongs to the corresponding photovoltaic string.

6. The photovoltaic system optimizer network update method according to claim 1, characterized in that, After determining that at least one of the optimizers has failed to complete network formation, the process further includes: The inverter determines whether the number of optimizers that have not completed networking is less than a preset number; If so, then execute the steps of controlling the inverter or keeping the optimizer that has completed networking running, and controlling the optimizer that has not completed networking to actively bypass; Otherwise, the inverter first sets the output voltage limit value and / or output current limit value for each of the optimizers, and then controls each of the optimizers to start; then the inverter controls the input terminals of the corresponding Boost circuits to maintain a short circuit state for a preset duration according to preset rules, and determines the optimizer connected to each Boost circuit according to the output electrical parameters of all the optimizers under each short circuit state, and marks the topology location information of each optimizer according to each of the serial numbers, thus completing the networking of each optimizer.

7. The photovoltaic system optimizer network update method according to claim 6, characterized in that, The output electrical parameters include: output voltage, and / or, output current; The inverter determines the optimizer connected to 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.

8. The photovoltaic system optimizer network update method according to claim 6, 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.

9. The photovoltaic system optimizer network update method according to claim 6, characterized in that, After determining the optimizer connected to each Boost circuit, the process also includes: The inverter determines whether the electrical states of each optimizer in the parallel photovoltaic string connected to the Boost circuit are consistent. If all the electrical states are consistent, then the corresponding parallel photovoltaic string is determined to be a parallel photovoltaic string with no voltage difference. If the electrical states are not consistent, the inverter first determines that the optimizer whose output current is greater than the preset positive current value or less than the preset negative current value belongs to the same photovoltaic string; then, if the number of photovoltaic strings in the corresponding parallel photovoltaic strings is greater than 2, it determines that the other photovoltaic strings are the parallel no-voltage photovoltaic strings. For the parallel photovoltaic strings with no voltage drop, the inverter controls one of the optimizers to change its output voltage at least once, and distinguishes the photovoltaic strings to which each optimizer belongs based on the electrical state of each optimizer under each control.

10. The photovoltaic system optimizer network update method according to claim 9, characterized in that, Changing the output voltage includes: active bypass; or, If the inverter has 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: the inverter controlling the output voltage of each of the optimizers to reach the output voltage limit value; and changing the output voltage, including: increasing or decreasing the output voltage limit value.

11. The photovoltaic system optimizer network update method according to claim 9, characterized in that, The electrical state includes at least one of the following: output voltage, output current, and operating state; The photovoltaic strings to which each optimizer belongs are distinguished by the electrical state of each optimizer under each control, including: If the direction of changing the output voltage is to decrease, then the optimizer that satisfies at least one of the following conditions: the output voltage is the output voltage limit value, the output current is the negative output current limit value, and the operating state is the reverse input state, is in the same photovoltaic string as the optimizer that changes the output voltage. If the direction of the output voltage is changed to increase, then the optimizer that satisfies at least one of the following conditions: the output voltage is less than the output voltage limit, the output current is positive, and the operating state is positive output state, is in the same photovoltaic string as the optimizer that changes the output voltage. In addition, other optimizers are identified as belonging to other photovoltaic strings.

12. The method for updating the optimizer network of a photovoltaic system according to any one of claims 1 to 11, characterized in that, The inverter compares the output current of each unconnected optimizer with the current of each photovoltaic string, and then further includes: If the current deviation of at least two photovoltaic strings is within a preset range, the inverter controls the input voltage of each Boost circuit one by one, so that each circuit changes at least once. After each voltage change, the inverter performs a step of comparing the output current of each unconnected optimizer with the current of each photovoltaic string, until the photovoltaic string to which each unconnected optimizer belongs is determined.

13. The photovoltaic system optimizer network update method according to claim 12, characterized in that, After each voltage change, the inverter performs a step of comparing the output current of each unconnected optimizer with the current of each photovoltaic string. Following this, the process further includes: If at least one of the optimizers has not completed networking and its output current does not match the current of all photovoltaic strings, it is determined that it does not belong to the photovoltaic system.

14. 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 update method for the photovoltaic system as described in any one of claims 1 to 13.

15. The photovoltaic system according to claim 14, 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.

16. The photovoltaic system according to claim 14 or 15, characterized in that, Each Boost circuit is integrated into the inverter. Inside the inverter, the input terminal of the 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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