Power converter, control method and device, medium and energy system

Abstract

The embodiment of the invention provides a power converter, a control method and device, a medium and an energy system. According to the power converter, the control method and device, the medium and the energy system, a photovoltaic string connected with a first target direct current-direct current conversion circuit in a plurality of direct current-direct current conversion circuits is controlled to execute current-voltage scanning; and a bypass switch of a second target DC-DC conversion circuit in the plurality of DC-DC conversion circuits is controlled to be closed, so that the output current of the first target DC-DC conversion circuit is utilized to carry out current backflow on the photovoltaic string connected with the second target DC-DC conversion circuit, therefore, the current-voltage scanning and the current backflow of the photovoltaic string are carried out at the same time, the total time required by the current-voltage scanning and the current backflow of the photovoltaic string is effectively reduced, and the detection efficiency of the photovoltaic string is improved.

Description

Technical Field

[0001] The embodiments in this application relate to the field of photovoltaic power generation technology, specifically to a power converter and control method, device, medium, and energy system. Background Technology

[0002] To evaluate the performance of photovoltaic (PV) strings, determine their optimal operating point, and / or detect faults, the power converter needs to monitor the output current and voltage of the PV strings, a process known as a current-voltage scan (IV scan). Furthermore, to improve PV power generation efficiency and / or extend the lifespan of the PV strings, in some cases, reverse current is required to induce electroluminescence (EL) effects within the PV strings. This allows for EL detection of internal defects such as microcracks, fragments, edge chipping, poor soldering, and broken grids.

[0003] In existing photovoltaic systems, performing IV scanning and current backfeeding on photovoltaic strings takes a long time, resulting in low detection efficiency for photovoltaic strings. Summary of the Invention

[0004] In view of this, this application provides a power converter and control method, apparatus, medium and energy system to improve the detection efficiency of photovoltaic strings.

[0005] In a first aspect, embodiments of this application provide a power converter, comprising: a plurality of DC-DC conversion circuits; wherein the DC-DC conversion circuits have a first DC side for connecting a photovoltaic string, and the second DC sides of the plurality of DC-DC conversion circuits are connected in parallel; the first DC side of the DC-DC conversion circuit has a first positive line, the second DC side has a second positive line, and a bypass switch is connected between the first positive line and the second positive line; the plurality of DC-DC conversion circuits include a first target DC-DC conversion circuit and a second target DC-DC conversion circuit; and a control device for controlling the bypass switch of the second target DC-DC conversion circuit to close during a current-voltage scan of the photovoltaic string connected to the first target DC-DC conversion circuit, so as to use the output current of the first target DC-DC conversion circuit to perform current reverse injection on the photovoltaic string connected to the second target DC-DC conversion circuit.

[0006] Optionally, the power converter includes a DC-AC conversion circuit, wherein the DC side of the DC-AC conversion circuit is connected to the second DC side of the plurality of DC-DC conversion circuits, and the AC side of the DC-AC conversion circuit is used to connect to the power grid through a grid-connected switch.

[0007] Optionally, the control device determines the maximum string voltage among the photovoltaic strings connected to the plurality of DC-DC converter circuits respectively; controls the output voltage of the second DC side of the first target DC-DC converter circuit to a specified voltage; wherein the specified voltage is greater than or equal to the sum of the maximum string voltage and a preset voltage margin; while controlling the second DC side of the first target DC-DC converter circuit to maintain the specified voltage, the control device performs a current-voltage scan on the photovoltaic strings connected to the first target DC-DC converter circuit.

[0008] Optionally, the plurality of DC-DC converter circuits further include a third target DC-DC converter circuit; the control device is configured to, during the process of controlling the photovoltaic string connected to the first target DC-DC converter circuit to perform current-voltage scanning, control the closing of the bypass switch of the second target DC-DC converter circuit and control the closing of the bypass switch of the third target DC-DC converter circuit, so as to use the output current of the first target DC-DC converter circuit to perform current reverse injection to the photovoltaic string connected to the second target DC-DC converter circuit and to perform current reverse injection to the photovoltaic module connected to the third target DC-DC converter circuit.

[0009] Secondly, embodiments of this application provide a control method for a power converter, comprising: controlling a photovoltaic string connected to a first target DC-DC converter circuit to perform a current-voltage scan, and controlling the bypass switch of a second target DC-DC converter circuit to close, so as to use the output current of the first target DC-DC converter circuit to perform current reverse injection to the photovoltaic string connected to the second target DC-DC converter circuit; wherein, the power converter includes a plurality of DC-DC converter circuits; the DC-DC converter circuits have a first DC side for connecting the photovoltaic string, and the second DC sides of the plurality of DC-DC converter circuits are connected in parallel; the first DC side of the DC-DC converter circuits has a first positive line, the second DC side has a second positive line, and a bypass switch is connected between the first positive line and the second positive line; the plurality of DC-DC converter circuits include the first target DC-DC converter circuit and the second target DC-DC converter circuit.

[0010] Optionally, during the current-voltage scanning process of the photovoltaic string connected to the first target DC-DC converter circuit, the bypass switch of the second target DC-DC converter circuit is closed to utilize the output current of the first target DC-DC converter circuit to perform current reverse injection on the photovoltaic string connected to the second target DC-DC converter circuit. This includes: determining the maximum string voltage among the photovoltaic strings connected to the plurality of DC-DC converter circuits respectively; controlling the output voltage of the second DC side of the first target DC-DC converter circuit to a specified voltage; wherein the specified voltage is greater than or equal to the sum of the maximum string voltage and a preset voltage margin; while maintaining the specified voltage on the second DC side of the first target DC-DC converter circuit, current-voltage scanning is performed on the photovoltaic string connected to the first target DC-DC converter circuit, and the bypass switch of the second target DC-DC converter circuit is closed to utilize the output current of the first target DC-DC converter circuit to perform current reverse injection on the photovoltaic string connected to the second target DC-DC converter circuit.

[0011] Optionally, the control method further includes: during the process of controlling the photovoltaic string connected to the first target DC-DC converter circuit to perform current-voltage scanning, controlling the bypass switch of the third target DC-DC converter circuit to close, so as to use the output current of the first target DC-DC converter circuit to perform current reverse injection to the photovoltaic string connected to the second target DC-DC converter circuit, and to perform current reverse injection to the photovoltaic module connected to the third target DC-DC converter circuit; wherein, the plurality of DC-DC converter circuits further includes the third target DC-DC converter circuit.

[0012] Thirdly, embodiments of this application provide a control device, including a processor and a memory, wherein the memory is used to store programs, instructions or code, and the processor is used to execute the programs, instructions or code in the memory to perform the control method as described in any of the foregoing.

[0013] Fourthly, embodiments of this application provide a computer-readable storage medium storing a computer program, which is loaded by a processor to execute the control method described in any of the foregoing claims.

[0014] Fifthly, embodiments of this application provide an energy system including a power converter as described in any of the foregoing claims.

[0015] In several embodiments provided in this application, during the current-voltage scanning process of the photovoltaic string connected to the first target DC-DC converter circuit in multiple DC-DC converter circuits, the bypass switch of the second target DC-DC converter circuit in multiple DC-DC converter circuits is closed to utilize the output current of the first target DC-DC converter circuit to perform current reverse injection on the photovoltaic string connected to the second DC-DC converter circuit. This allows the current-voltage scanning and current reverse injection of the photovoltaic string to be performed simultaneously, effectively reducing the total time required for the current-voltage scanning and current reverse injection of the photovoltaic string and improving the detection efficiency of the photovoltaic string. Attached Figure Description

[0016] 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.

[0017] Figure 1 The circuit structure of a power converter provided for one embodiment of this application is shown; wherein, three DC-DC conversion circuits and corresponding photovoltaic strings are illustrated.

[0018] Figure 2 A schematic diagram of the circuit structure of a power converter provided in one embodiment of this application is shown; wherein, four DC-DC conversion circuits and corresponding connected photovoltaic strings are shown.

[0019] Figure 3 This is a schematic diagram of a control device provided in one embodiment of this application. Detailed Implementation

[0020] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0021] In the description of the embodiments of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0022] In related technologies, IV scanning and current reverse feeding for photovoltaic (PV) strings are performed separately. For example, in a grid-connected PV system, IV scanning of the PV string needs to be performed by the power converter during grid-connected operation. When current reverse feeding is required, the power converter needs to switch to reverse rectification mode to obtain energy from the grid and feed it back into the corresponding PV string. The separate IV scanning and current reverse feeding of the PV string take a long time, resulting in relatively low detection efficiency. Therefore, this application provides a power converter, control method, device, medium, and energy system that can simultaneously perform IV scanning and current reverse feeding control of PV strings, thereby improving the detection efficiency of PV strings.

[0023] Please see Figure 1 As shown, in some embodiments, the power converter 1 includes a DC-DC conversion module and a control device 12, with the control device 12 connected to the DC-DC conversion module. The DC-DC conversion module includes multiple DC-DC conversion circuits, namely DC-DC conversion circuit 111 to DC-DC conversion circuit 11n, where n is an integer greater than or equal to 2.

[0024] Each DC-DC converter circuit has a first DC side and a second DC side connected to the photovoltaic string, wherein the second DC sides of each DC-DC converter circuit are connected in parallel. Each DC-DC converter circuit's first DC side has a first positive line, and each DC-DC converter circuit's second DC side has a second positive line, with each second positive line connected to the positive DC bus BUS+. A bypass switch is connected between the corresponding first and second positive lines. Figure 1 In the DC-DC converter circuit 111, the first positive line is 1111, the second positive line is 1112, and the bypass switch is S111; the DC-DC converter circuit 11n has a first positive line 11n1, a second positive line 11n2, and a bypass switch S1n1. The DC-DC converter circuit 111 is connected to the positive terminal PV1+ of the photovoltaic string 21 via the first positive line 1111, and the DC-DC converter circuit 11n is connected to the positive terminal PVn+ of the photovoltaic string 2n via the first positive line 11n1.

[0025] It is understood that in some embodiments, the first DC side of each DC-DC converter circuit also has a first negative line, and the second DC side also has a second negative line. The first negative line of each DC-DC converter circuit is connected to the negative terminal of the corresponding photovoltaic string, such as the first negative line of DC-DC converter 111 being connected to the negative terminal PV1- of photovoltaic string 21, and the first negative line of DC-DC converter 11n being connected to the negative terminal PVn- of photovoltaic string 2n. The second negative lines of each DC-DC converter circuit are connected to each other via the negative DC bus BUS-. A capacitor Cbus is connected between the positive DC bus BUS+ and the negative DC bus BUS-.

[0026] The multiple DC-DC converter circuits include a first target DC-DC converter circuit and a second target DC-DC converter circuit. The first target DC-DC converter circuit is the one among the multiple DC-DC converter circuits that performs IV scanning on the corresponding photovoltaic string, and the second target DC-DC converter circuit is the one among the multiple DC-DC converter circuits that performs current reverse feeding on the corresponding photovoltaic string.

[0027] The control device is used to control the closing of the bypass switch of the second target DC-DC converter circuit during the process of controlling the photovoltaic string connected to the first target DC-DC converter circuit to perform current reverse injection to the photovoltaic string connected to the second target DC-DC converter circuit by using the output current of the first target DC-DC converter circuit.

[0028] For example, taking DC-DC converter circuit 111 as the first target DC-DC converter circuit and DC-DC converter circuit 11m as the second target DC-DC converter circuit as an example, the control process of control device 12 will be described in detail. Here, m is a positive integer greater than 1 and less than or equal to n. The first positive line 11m1 of DC-DC converter circuit 11m is connected to the positive terminal PVm+ of photovoltaic string 2m, the first negative line 11m1 of DC-DC converter circuit 11m is connected to the positive terminal PVm- of photovoltaic string 2m, the second positive line 11m2 of DC-DC converter circuit 11m is connected to the second positive lines of other DC-DC converter circuits, and the bypass switch 11m corresponds to DC-DC converter circuit 11m. Figure 1To clearly describe the control process of the control device 12, a power converter 1 including at least three DC-DC conversion circuits is illustrated. However, in other embodiments, the power converter 1 may include only two DC-DC conversion circuits. When the power converter 1 includes only two DC-DC conversion circuits, one of the two DC-DC conversion circuits is a first target DC-DC conversion circuit, and the other is a second target DC-DC conversion circuit. During the IV scan of the photovoltaic string 21, the first DC power output from the photovoltaic string 21 is output to the first DC side of the DC-DC conversion circuit 111. The control device 21 controls the DC-DC conversion circuit 111 to perform DC conversion on the first DC power input from the first DC side to obtain a second DC power that meets preset conditions, and outputs the second DC power through its second DC side. At the same time, the control device 21 controls the bypass switch S11m of the DC-DC conversion circuit 11m to close, so that the second DC power can be reverse-fed through the bypass switch S11m to the photovoltaic string 2m connected to the DC-DC conversion circuit 11m, so that the photovoltaic string 2m generates an electroluminescent effect. Therefore, the power converter 1 provided in this application embodiment can perform current back-feeding on the photovoltaic string 2m while performing IV scanning on the photovoltaic string 21, thereby enabling the IV scanning and EL detection of the photovoltaic string to be performed simultaneously, effectively improving the detection efficiency of the photovoltaic string.

[0029] In the power converter provided in this application embodiment, during the current-voltage scanning process of the photovoltaic string connected to the first target DC-DC converter circuit in the multiple DC-DC converter circuits, the bypass switch of the second target DC-DC converter circuit in the multiple DC-DC converter circuits is closed to utilize the output current of the first target DC-DC converter circuit to perform current reverse injection on the photovoltaic string connected to the second target DC-DC converter circuit. This effectively reduces the total time required for the current-voltage scanning and current reverse injection of the photovoltaic string and improves the detection efficiency of the photovoltaic string.

[0030] In some embodiments, the control device may determine the first target DC-DC converter circuit and the second target DC-DC converter circuit based on the current state of each DC-DC converter circuit, or it may determine the first target DC-DC converter circuit and the second target DC-DC converter circuit based on a preset control strategy. Alternatively, the control device may determine the first target DC-DC converter circuit and the second target DC-DC converter circuit based on control commands received from a host computer.

[0031] In some embodiments, each DC-DC converter circuit can be a boost converter circuit, such as a boost converter circuit. The first DC side of each DC-DC converter circuit is the side containing its DC input terminal, and the second DC side is the side containing its DC output terminal. The DC output terminal of each DC-DC converter circuit includes a positive DC output terminal connected to the corresponding second positive line and a negative DC output terminal connected to the corresponding second negative line.

[0032] In some embodiments, the power converter 1 further includes a DC-AC converter circuit 13. The DC side of the DC-AC converter circuit 13 is connected to the second DC side of multiple DC-DC converter circuits, and the AC side is used to connect to the power grid 4 via a grid connection switch 3. During the conduction of the grid connection switch 3, the DC-AC converter circuit 13 converts the second DC power output from the multiple DC-DC converter circuits into AC power, and inputs this AC power into the power grid 4 via the grid connection switch 3 to achieve photovoltaic grid connection. The positive terminal of the DC side of the DC-AC converter circuit 13 is connected to the positive DC bus BUS+, and the negative terminal of the DC side is connected to the negative DC bus BUS-.

[0033] In some embodiments, while performing IV scanning on the photovoltaic string corresponding to the first target DC-DC converter circuit, and performing current reverse injection on the photovoltaic string connected to the second target DC-DC converter circuit, the control device 12 controls the grid connection switch 3 to disconnect, so that the power converter 1 performs IV scanning and current reverse injection on the photovoltaic string under islanded conditions, thereby being unaffected by the power grid 4 and improving the control flexibility of the power converter 1.

[0034] Islanding condition refers to the state where the power converter 1 is disconnected from the external power supply. The external power supply can be the power grid 4, a generator, or other power supply circuits. The power converter 1 provided in this application embodiment can, under islanding condition, control the first target DC-DC converter circuit to perform current and voltage scanning on the corresponding photovoltaic string, while simultaneously outputting a second DC current that meets preset conditions, and control the closing of the bypass switch corresponding to the second target DC-DC converter circuit. This allows the second DC current output by the first target DC-DC converter circuit to perform current reverse feeding on the photovoltaic string connected to the second target DC-DC converter circuit, thereby achieving coordinated control of IV scanning and current reverse feeding of the photovoltaic string without the need for additional additions or changes to the circuitry of the power converter 1, effectively improving the detection efficiency of the photovoltaic string.

[0035] In some embodiments, the control device can determine the maximum string voltage in the photovoltaic strings connected to the plurality of DC-DC converter circuits respectively; control the output voltage of the second DC side of the first target DC-DC converter circuit to a specified voltage; wherein the specified voltage is greater than or equal to the sum of the maximum string voltage and a preset voltage margin; while controlling the second DC side of the first target DC-DC converter circuit to maintain the specified voltage, the control device performs a current-voltage scan on the photovoltaic strings connected to the first target DC-DC converter circuit.

[0036] In this embodiment, the maximum string voltage is the largest among the string voltages of the photovoltaic strings connected by multiple DC-DC converter circuits. For example, if the string voltage of photovoltaic string 21 is Vpv1 and the string voltage of photovoltaic string 2n is Vpvn, then the maximum string voltage Vpvmax is the largest among the string voltages Vpv1 to Vpvn.

[0037] In this embodiment, the output voltage of the second DC side of the first target DC-DC converter circuit refers to the voltage input from the first target DC-DC converter circuit to the positive DC bus BUS+. The control device 12 controls the output voltage of the second DC side of the first target DC-DC converter circuit to the positive DC bus BUS+ to a specified voltage. That is, the control device 12 controls the output voltage of the first target DC-DC converter circuit to make the voltage on the positive DC bus BUS+ a specified voltage.

[0038] In this embodiment, the voltage on the positive DC bus BUS+ is maintained at a specified voltage, so that the current on the positive DC bus BUS+ can be reverse-fed to the photovoltaic string connected to the second target DC-DC converter circuit via the bypass switch of the second target DC-DC converter circuit, thereby realizing reverse-fed power to the photovoltaic string.

[0039] In this application, V1 represents the preset voltage margin. The control device 12 controls the bus voltage Vbus on the positive DC bus BUS+ to maintain a specified voltage, which is greater than or equal to the sum of the maximum string voltage Vpvmax and the preset voltage margin V1. By superimposing the predetermined voltage margin V1 on the maximum string voltage Vpvmax as the specified voltage, the output voltage of the first target DC-DC converter circuit is always greater than the maximum string voltage Vpvmax, thereby enabling reverse current feeding to the photovoltaic string at the maximum string voltage Vpvmax.

[0040] In one specific embodiment, upon receiving a collaborative control command from the host computer, the control device 12 begins to execute collaborative control of IV scanning and current reverse injection. After receiving the aforementioned collaborative control command, the control device 12 controls the grid connection switch 3 to disconnect, so as to execute collaborative control of IV scanning and current reverse injection under islanded conditions.

[0041] The control device 12 can, according to the cooperative control command, select the DC-DC converter circuit that needs to perform current reverse injection as the second target DC-DC converter circuit, and determine the DC-DC converter circuit that needs to perform IV scanning as the first target DC-DC converter circuit. Specifically, the control device 12 can select DC-DC converter circuit 11m as the second target DC-DC converter circuit, and the remaining DC-DC converter circuits can each be selected as the first target DC-DC converter circuit. In some embodiments, one or more DC-DC converter circuits 111 to 11n can be selected as the first target DC-DC converter circuit. Wherein, m is 1 to n or any integer.

[0042] The control device 12 can acquire the string voltages Vpv1 to Vpvn of the photovoltaic strings connected to DC-DC converters 111 to 11n respectively, and can compare them to obtain the maximum string voltage Vpvmax. The control device 12 can control the output voltage of the second DC side of the DC-DC converter 111 to increase to a specified voltage, so that the bus voltage Vbus on the positive DC bus BUS+ is greater than or equal to the sum of the maximum string voltage Vpvmax and the preset voltage margin V1, and control the bypass switch S11m to close. Then, the control device 12 controls the voltage Vpv1 of the photovoltaic string 21 to gradually decrease in steps Vstep, and determines whether the voltage Vpv1 of the photovoltaic string 21 has decreased to the corresponding minimum voltage V2_1. If so, it indicates that the IV scan of the photovoltaic string 21 is complete, the control device 12 controls the DC-DC converter 111 to stop working, and controls the bypass switch S11m to open.

[0043] The control device 12 can control the next photovoltaic string requiring IV scanning to perform IV scanning in the same way, until all photovoltaic strings requiring IV scanning have completed IV scanning and output the IV curve corresponding to each photovoltaic string. Specifically, the control device 12 first controls the output voltage of the DC-DC converter circuit corresponding to the photovoltaic string undergoing IV scanning to reach a specified voltage, then controls the bypass switch S11m to close, and opens the bypass switch S11m after completing the IV scanning. This enables the IV scanning device for each photovoltaic string to perform current reverse injection into the photovoltaic string 2m.

[0044] In some embodiments, when it is necessary to perform current reverse feeding for multiple DC-DC converter circuits in the power converter 1, one DC-DC converter circuit can be used as the second target DC-DC converter circuit to perform the aforementioned cooperative control.

[0045] In some embodiments, the control device 12 can control the voltage of the photovoltaic string to decrease from the open-circuit voltage V2 to a set minimum voltage V3 in steps of a certain step size Vstep. The step size Vstep can be a fixed value or a value that varies according to a set step size variation strategy.

[0046] In some embodiments, the first target DC-DC converter circuit can provide reverse current to one DC-DC converter circuit or provide reverse current to multiple DC-DC converter circuits simultaneously, so that multiple corresponding photovoltaic strings are in a reverse current state.

[0047] In some embodiments, the plurality of DC-DC converter circuits further include a third target DC-DC converter circuit. The control device 12 is also configured to, during the IV scan of the photovoltaic string connected to the first target DC-DC converter circuit, control the closing of the bypass switch of the second target DC-DC converter circuit and the closing of the bypass switch of the third target DC-DC converter circuit, so as to utilize the output current of the first target DC-DC converter circuit to provide reverse current to the photovoltaic string connected to the second target DC-DC converter circuit and to provide reverse current to the photovoltaic module connected to the third target DC-DC converter circuit. This allows the first target DC-DC converter circuit to simultaneously provide reverse current to the photovoltaic strings connected to the two DC-DC converter circuits during the IV scan of the corresponding photovoltaic string, enabling multiple photovoltaic strings to simultaneously undergo reverse current during the IV scan, thereby further improving the detection efficiency of the photovoltaic strings.

[0048] Please see Figure 2 As shown, for example, taking DC-DC converter 111 as the first target DC-DC converter, DC-DC converter 11m as the second target DC-DC converter, and DC-DC converter 11k as the third target DC-DC converter, the power converter 1 will be further described in detail. Here, k is a positive integer different from m, and both k and m are positive integers greater than 1 and less than or equal to n. DC-DC converter 111 and DC-DC converter 11m have been described in detail in the above embodiments and will not be repeated here.

[0049] The first positive line 11k1 of the DC-DC converter circuit 11k is connected to the positive terminal PVk+ of the photovoltaic string 2k, the first negative line of the DC-DC converter circuit 11k is connected to the negative terminal PVk- of the photovoltaic string 2k, the second positive line 11k2 of the DC-DC converter circuit 11k is connected to the second positive lines of other DC-DC converter circuits, and a bypass switch S11k is connected between the first positive line 11k1 and the second positive line 11k2 of the DC-DC converter circuit 11k. Figure 2 To clearly describe the control process of the control device 12, a power converter 1 comprising at least four DC-DC conversion circuits is illustrated. However, in other embodiments, when the power converter 1 also includes a third target DC-DC conversion circuit, the power converter 1 may also include only three DC-DC conversion circuits. When the power converter 1 includes only three DC-DC conversion circuits, one of the three DC-DC conversion circuits is the first target DC-DC conversion circuit, and the remaining two are the second target DC-DC conversion circuit and the third target DC-DC conversion circuit, respectively.

[0050] When the control device 12 controls the DC-DC converter circuit 111 to perform IV scanning on the photovoltaic string 21, it first controls the second DC side of the DC-DC converter circuit 111 to output a specified voltage. At this time, it controls the bypass switches S11m and S11k to close, so as to provide reverse current to the photovoltaic strings 2m and 2k during the IV scanning process of the DC-DC converter circuit 111. When the DC-DC converter circuit 111 completes the IV scanning, it opens the bypass switches S11m and S11k. The control device 12 can repeat the above control during the IV scanning process of the next photovoltaic string, so as to achieve multiple reverse current injections to the photovoltaic strings 2m and 2k.

[0051] In some embodiments, this application also provides a control method for controlling a power converter 1 provided in any embodiment of this application. The control method provided in this application embodiment can be executed by a control device 12 in the power converter 1. The control device 12 can be an electronic device with a certain operating power. Of course, in some embodiments, the control device 12 can also refer to a program module running in an electronic device.

[0052] The control method for a power converter provided in this application includes: during the current-voltage scanning process of a photovoltaic string connected to a first target DC-DC converter circuit, controlling the closing of a bypass switch of a second target DC-DC converter circuit to utilize the output current of the first target DC-DC converter circuit to perform current reverse injection on the photovoltaic string connected to the second target DC-DC converter circuit. The power converter includes multiple DC-DC converter circuits; each DC-DC converter circuit has a first DC side for connecting the photovoltaic string, and the second DC sides of the multiple DC-DC converter circuits are connected in parallel; the first DC side of the DC-DC converter circuit has a first positive line, and the second DC side has a second positive line, with a bypass switch connected between the first positive line and the second positive line; the multiple DC-DC converter circuits include the first target DC-DC converter circuit and the second target DC-DC converter circuit.

[0053] The control method provided in this application embodiment can control the photovoltaic string connected to the first target DC-DC converter circuit in multiple DC-DC converter circuits to perform current-voltage scanning during the process, and control the bypass switch of the second target DC-DC converter circuit in multiple DC-DC converter circuits to close, so as to realize the current reverse injection of the photovoltaic string connected to the second DC-DC converter circuit by using the output current of the first target DC-DC converter circuit. In this way, the current-voltage scanning and current reverse injection of the photovoltaic string can be performed simultaneously, which can effectively reduce the total time required for the current-voltage scanning and current reverse injection of the photovoltaic string, thereby improving the detection efficiency of the photovoltaic string.

[0054] The specific functions and effects implemented in this embodiment can be explained by referring to the foregoing embodiments, and will not be repeated here.

[0055] In some embodiments, this application also provides an energy system, which includes the power converter provided in any of the above embodiments.

[0056] In this embodiment, the functions and effects achieved by the energy system can be explained in comparison with the aforementioned embodiments, and will not be repeated here.

[0057] This application provides a control device including a processor and a memory. The memory is used to store programs, instructions, or code, and the processor is used to execute the programs, instructions, or code in the memory to perform the methods described in the foregoing embodiments.

[0058] In this embodiment, the control device controls the closing of the bypass switch corresponding to the second target DC-DC converter circuit during the IV scan of the photovoltaic string connected to the first target DC-DC converter circuit. This allows the current output from the first DC-DC converter circuit to be reverse-fed to the photovoltaic string connected to the second DC-DC converter circuit via the bypass switch of the second target DC-DC converter circuit. Thus, without adding or changing the circuit structure of the power converter, the IV scan and current reverse-fed of the photovoltaic string are performed simultaneously. The control method is more flexible and convenient, and effectively improves the detection efficiency of the photovoltaic string.

[0059] In some embodiments, please refer to Figure 3 The control device 12 may include a memory 121 and a processor 122. The processor 122 may be connected to each DC-DC converter circuit and may issue control commands to each DC-DC converter circuit. The memory may be random access memory (RAM), flash memory, read-only memory (ROM), EPROM, non-volatile read-only memory (EPROM), registers, hard disk, removable disk, etc.

[0060] The memory 121 can store computer instructions. When the computer instructions stored in the memory 121 are executed by the processor 122, the processor 122 can be used to execute the control method of the power converter 1.

[0061] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape) or a semiconductor medium (e.g., solid-state disk (SSD)).

[0062] This application also provides a readable storage medium for storing the methods or algorithms provided in the above embodiments. Examples include random access memory (RAM), flash memory, read-only memory (ROM), EPROM, non-volatile read-only memory (Electronic Programmable ROM), registers, hard disks, removable disks, or any other form of storage medium in the art.

[0063] It is understood that the term "connection" in the embodiments of this application can be interpreted as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc. can transmit electrical signals or data to each other.

[0064] It is understood that the specific examples in this document are only intended to help those skilled in the art better understand the embodiments of this application, and are not intended to limit the scope of the invention.

[0065] It is understood that in the various embodiments of this application, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0066] It is understood that the various embodiments described in this application can be implemented individually or in combination, and the embodiments of this application are not limited in this respect.

[0067] Unless otherwise stated, all technical and scientific terms used in the embodiments of this application have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items. The singular forms "a," "the," and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0068] Those skilled in the art will 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, or a combination of computer software and electronic hardware. 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 implementation should not be considered beyond the scope of this application.

[0069] The above description is merely a specific embodiment of this application, but the scope of protection of this invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this invention should be determined by the scope of the claims.

Claims

1. A power converter, characterized by, The power converter comprises: a plurality of direct-current-direct-current conversion circuits; wherein the direct-current-direct-current conversion circuit has a first direct-current side for connecting a photovoltaic string, and the second direct-current sides of the plurality of direct-current-direct-current conversion circuits are connected in parallel; the first direct-current side of the direct-current-direct-current conversion circuit has a first positive line, the second direct-current side has a second positive line, and a bypass switch is connected between the first positive line and the second positive line; the plurality of direct-current-direct-current conversion circuits comprise a first target direct-current-direct-current conversion circuit and a second target direct-current-direct-current conversion circuit; a control device for controlling the bypass switch of the second target direct-current-direct-current conversion circuit to be closed to use the output current of the first target direct-current-direct-current conversion circuit to perform current back-feeding on the photovoltaic string connected to the second target direct-current-direct-current conversion circuit in the process of controlling the photovoltaic string connected to the first target direct-current-direct-current conversion circuit to perform current-voltage scanning.

2. The power converter of claim 1, wherein, The power converter comprises: a direct-current-alternating-current conversion circuit, the direct-current side of the direct-current-alternating-current conversion circuit is connected with the second direct-current side of the plurality of direct-current-direct-current conversion circuits, and the alternating-current side of the direct-current-alternating-current conversion circuit is used to be connected with a power grid through a grid connection switch.

3. The power converter of claim 1, wherein, The control device determines the maximum string voltage in the photovoltaic strings connected by the plurality of direct-current-direct-current conversion circuits respectively; controls the output voltage of the second direct-current side of the first target direct-current-direct-current conversion circuit to be a specified voltage; wherein the specified voltage is greater than or equal to the sum of the maximum string voltage and a preset voltage margin; and the control device performs current-voltage scanning on the photovoltaic string connected to the first target direct-current-direct-current conversion circuit while controlling the second direct-current side of the first target direct-current-direct-current conversion circuit to maintain the specified voltage.

4. The power converter of claim 1, wherein, The plurality of direct-current-direct-current conversion circuits further comprise a third target direct-current-direct-current conversion circuit; The control device controls the bypass switch of the second target direct-current-direct-current conversion circuit to be closed and controls the bypass switch of the third target direct-current-direct-current conversion circuit to be closed to use the output current of the first target direct-current-direct-current conversion circuit to perform current back-feeding on the photovoltaic string connected to the second target direct-current-direct-current conversion circuit and perform current back-feeding on the photovoltaic component connected to the third target direct-current-direct-current conversion circuit in the process of controlling the photovoltaic string connected to the first target direct-current-direct-current conversion circuit to perform current-voltage scanning.

5. A control method of a power converter, characterized by, The power converter comprises: controlling the bypass switch of the second target direct-current-direct-current conversion circuit to be closed to use the output current of the first target direct-current-direct-current conversion circuit to perform current back-feeding on the photovoltaic string connected to the second target direct-current-direct-current conversion circuit in the process of controlling the photovoltaic string connected to the first target direct-current-direct-current conversion circuit to perform current-voltage scanning. The power converter comprises a plurality of DC-DC conversion circuits; the DC-DC conversion circuit has a first DC side for connecting a photovoltaic string, and a second DC side of the plurality of DC-DC conversion circuits is connected in parallel; the first DC side of the DC-DC conversion circuit has a first positive line, the second DC side has a second positive line, and the bypass switch is connected between the first positive line and the second positive line; the plurality of DC-DC conversion circuits comprises the first target DC-DC conversion circuit and the second target DC-DC conversion circuit.

6. The control method according to claim 5, characterized by In the process of controlling the photovoltaic string connected to the first target DC-DC conversion circuit to perform current-voltage scanning, the bypass switch of the second target DC-DC conversion circuit is controlled to be closed to use the output current of the first target DC-DC conversion circuit to perform current backflow on the photovoltaic string connected to the second target DC-DC conversion circuit, comprising: determining the maximum string voltage in the photovoltaic strings connected to the plurality of DC-DC conversion circuits respectively; controlling the output voltage of the second DC side of the first target DC-DC conversion circuit to be a specified voltage; wherein the specified voltage is greater than or equal to the sum of the maximum string voltage and a preset voltage margin; In the case of controlling the second DC side of the first target DC-DC conversion circuit to maintain the specified voltage, the photovoltaic string connected to the first target DC-DC conversion circuit is subjected to current-voltage scanning.

7. The control method according to claim 5, characterized by, The control method further comprises: In the process of controlling the photovoltaic string connected to the first target DC-DC conversion circuit to perform current-voltage scanning, the bypass switch of the third target DC-DC conversion circuit is also controlled to be closed to use the output current of the first target DC-DC conversion circuit to perform current backflow on the photovoltaic string connected to the second target DC-DC conversion circuit and the photovoltaic component connected to the third target DC-DC conversion circuit; The plurality of DC-DC conversion circuits further comprises the third target DC-DC conversion circuit.

8. A control device characterized by comprising: The control method comprises a processor and a memory, the memory is used to store programs, instructions or codes, and the processor is used to execute the programs, instructions or codes in the memory to complete the control method as claimed in any one of claims 5-7.

9. A computer-readable storage medium, characterized in that, A computer program is stored, and the computer program is loaded by a processor to execute the control method as claimed in any one of claims 5-7.

10. An energy system characterized by, The power converter comprises a processor and a memory, the memory is used to store programs, instructions or codes, and the processor is used to execute the programs, instructions or codes in the memory to complete the control method as claimed in any one of claims 5-7.

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