Photovoltaic power generation system control method, device, power optimizer and storage medium

Abstract

The present application provides a photovoltaic power generation system control method, device, power optimizer and storage medium, which relates to the field of power electronics technology. The method includes: obtaining the input current and input voltage of the power optimizer; obtaining the actual input power according to the input voltage and input current; obtaining the output power according to the actual input power and a pre-generated first mapping curve; the first mapping curve is used to indicate the corresponding relationship between the output voltage and the output power of the power optimizer, and the first mapping curve includes: a linear power curve of a first voltage segment and a linear power curve of a second voltage segment, and the voltage corresponding to the second voltage segment is higher than the voltage corresponding to the first voltage segment; the bus voltage corresponding to the output power is output to the subsequent photovoltaic inverter, so that the subsequent photovoltaic inverter determines the target maximum power according to the bus voltage. This solution can effectively balance the competitive relationship between the power optimizer and the photovoltaic inverter, and avoid mismatch oscillation.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a photovoltaic power generation system control method, device, power optimizer and storage medium. Background Art

[0002] Photovoltaic power generation is a technology that uses the photovoltaic effect of semiconductor interfaces to directly convert light energy into electrical energy. It is mainly composed of three parts: photovoltaic panels (modules), controllers and inverters, and the main components are composed of electronic components. After solar cells are connected in series and packaged for protection, they can form large-area solar cell modules, which are then combined with power controllers and other components to form photovoltaic power generation devices.

[0003] At present, photovoltaic power generation systems include centralized and distributed systems. Among them, in centralized photovoltaic systems, photovoltaic panels are generally connected in series to form a high voltage input to the photovoltaic inverter, and the photovoltaic inverter performs the maximum power point tracking (MPPT) function; in distributed photovoltaic systems, the photovoltaic inverter consists of two stages, the front stage DC / DC completes the boost and MPPT functions, and the rear stage completes the stable input voltage and inversion functions. In addition, for the current centralized and distributed systems, if the photovoltaic panels are equipped with a power optimizer, the rear stage of the power optimizer is connected to the photovoltaic inverter, and the power optimizer performs the boost, isolation, MPPT and other functions, and the photovoltaic inverter completes the stable input voltage and inversion functions.

[0004] However, in the existing photovoltaic power generation system, only the case where the MPPT function is performed by a certain module in the "power optimizer" or "photovoltaic inverter" is considered. But when the "photovoltaic inverter" performs MPPT tracking and the "power optimizer" DC / DC also performs MPPT tracking at the same time, there are two MPPT DC / DC units in the entire system, and the two-level MPPT DC / DC units are trying to find the maximum power point through the disturbance strategy, which may lead to a certain competition relationship between the two-level MPPT, and even mismatch oscillation may occur. Summary of the invention

[0005] The purpose of the present invention is to provide a photovoltaic power generation system control method, device, power optimizer and storage medium to balance the competition between the power optimizer and the photovoltaic inverter and avoid mismatch oscillation.

[0006] To achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0007] In a first aspect, an embodiment of the present application provides a photovoltaic power generation system control method, which is applied to a power optimizer in a photovoltaic power generation system, comprising:

[0008] Obtain input current and input voltage of the power optimizer;

[0009] Obtaining actual input power according to the input voltage and the input current;

[0010] The output power is obtained according to the actual input power and a pre-generated first mapping curve; wherein the first mapping curve is used to indicate the corresponding relationship between the output voltage and the output power of the power optimizer, and the first mapping curve includes: a first voltage segment linear power curve and a second voltage segment linear power curve, wherein the voltage corresponding to the second voltage segment is higher than the voltage corresponding to the first voltage segment;

[0011] The bus voltage corresponding to the output power is output to a subsequent photovoltaic inverter, so that the subsequent photovoltaic inverter determines a target maximum power according to the bus voltage.

[0012] Optionally, the first mapping curve further includes: a third voltage segment and a constant power segment, wherein a voltage corresponding to the third voltage segment is higher than a voltage corresponding to the first voltage segment, and lower than a voltage corresponding to the second voltage segment;

[0013] The first voltage segment linear power curve is a linear curve in which power increases as voltage increases or power decreases as voltage decreases, and the second voltage segment linear power curve is a linear curve in which power decreases as voltage increases or power increases as voltage decreases.

[0014] Optionally, obtaining the output power according to the actual input power and a pre-generated first mapping curve includes:

[0015] If the bus voltage of the rear photovoltaic inverter after disturbance is detected to be within the first voltage segment or the second voltage segment, the output power is obtained according to the linear power curve of the first voltage segment or the linear power curve of the second voltage segment.

[0016] Optionally, obtaining the output power according to the actual input power and a pre-generated first mapping curve further includes:

[0017] If it is detected that the bus voltage of the rear-stage photovoltaic inverter after disturbance is within the third voltage section, the output power is obtained according to the constant power section of the third voltage section.

[0018] Optionally, obtaining the output power according to the third voltage segment and the constant power segment includes:

[0019] If the actual input power is less than or equal to the maximum limited power of the power optimizer, the actual input power is used as the output power.

[0020] Optionally, obtaining the output power according to the third voltage segment and the constant power segment further includes:

[0021] If the actual input power is greater than the maximum limited power, the maximum limited power is used as the output power.

[0022] Optionally, before obtaining the output power according to the actual input power and the pre-generated first mapping curve, the method further includes:

[0023] The corresponding relationships between the first voltage segment, the second voltage segment and the output power are adjusted respectively to obtain the first mapping curve.

[0024] Optionally, the adjusting the corresponding relationship between the first voltage segment, the second voltage segment and the output power respectively includes:

[0025] Adjusting the corresponding relationship between the first voltage segment and the output power to a linear relationship in which the power increases as the voltage increases;

[0026] The corresponding relationship between the second voltage segment and the output power is adjusted to a linear relationship in which the power decreases as the voltage increases.

[0027] Optionally, after obtaining the output power according to the actual input power and the pre-generated first mapping curve, the method further includes:

[0028] Determine a first given current according to a maximum power point and a given voltage corresponding to the maximum power point; wherein the maximum power point is a maximum power point unit in the power optimizer, obtained by perturbing an input voltage and an input current;

[0029] determining a second given current according to the output power and an output voltage corresponding to the output power;

[0030] Obtaining a minimum given current according to the first given current and the second given current;

[0031] Using the minimum given current, the duty cycle of the power optimizer is adjusted.

[0032] In a second aspect, an embodiment of the present application further provides a photovoltaic power generation system control method, wherein the photovoltaic power generation system control device comprises: an acquisition module, a processing module, and a determination module;

[0033] The acquisition module is used to acquire the input current and input voltage of the power optimizer;

[0034] The processing module is used to obtain the actual input power according to the input voltage and the input current; and obtain the output power according to the actual input power and a pre-generated first mapping curve; wherein the first mapping curve is used to indicate the corresponding relationship between the output voltage and the output power of the power optimizer, and the first mapping curve includes: a first voltage segment linear power curve and a second voltage segment linear power curve, wherein the voltage corresponding to the second voltage segment is higher than the voltage corresponding to the first voltage segment;

[0035] The determination module is used to output the bus voltage corresponding to the output power to the subsequent photovoltaic inverter, so that the subsequent photovoltaic inverter determines the target maximum power according to the bus voltage.

[0036] Optionally, the first mapping curve further includes: a third voltage segment and a constant power segment, wherein a voltage corresponding to the third voltage segment is higher than a voltage corresponding to the first voltage segment, and lower than a voltage corresponding to the second voltage segment;

[0037] The first voltage segment linear power curve is a linear curve in which power increases as voltage increases or power decreases as voltage decreases, and the second voltage segment linear power curve is a linear curve in which power decreases as voltage increases or power increases as voltage decreases.

[0038] Optionally, the processing module is further used to:

[0039] If the bus voltage of the rear photovoltaic inverter after disturbance is detected to be within the first voltage segment or the second voltage segment, the output power is obtained according to the linear power curve of the first voltage segment or the linear power curve of the second voltage segment.

[0040] Optionally, the processing module is further used to:

[0041] If it is detected that the bus voltage of the rear-stage photovoltaic inverter after disturbance is within the third voltage section, the output power is obtained according to the constant power section of the third voltage section.

[0042] Optionally, the processing module is further used to:

[0043] If the actual input power is less than or equal to the maximum limited power of the power optimizer, the actual input power is used as the output power.

[0044] Optionally, the processing module is further used to:

[0045] If the actual input power is greater than the maximum limited power, the maximum limited power is used as the output power.

[0046] Optionally, the device further comprises: an adjustment module;

[0047] The adjustment module is used to adjust the corresponding relationship between the first voltage segment, the second voltage segment and the output power respectively to obtain the first mapping curve.

[0048] Optionally, the adjustment module is further used to:

[0049] Adjusting the corresponding relationship between the first voltage segment and the output power to a linear relationship in which the power increases as the voltage increases;

[0050] The corresponding relationship between the second voltage segment and the output power is adjusted to a linear relationship in which the power decreases as the voltage increases.

[0051] Optionally, the processing module is further used to:

[0052] Determine a first given current according to a maximum power point and a given voltage corresponding to the maximum power point; wherein the maximum power point is a maximum power point unit in the power optimizer, obtained by perturbing an input voltage and an input current; determine a second given current according to the output power and an output voltage corresponding to the output power; obtain a minimum given current according to the first given current and the second given current;

[0053] The device further includes: an adjusting module, wherein the adjusting module is configured to adjust a duty cycle of the power optimizer using the minimum given current.

[0054] In the third aspect, an embodiment of the present application also provides a power optimizer, comprising: a processor, a storage medium and a bus, wherein the storage medium stores machine-readable instructions executable by the processor, and when the power optimizer is running, the processor communicates with the storage medium through the bus, and the processor executes the machine-readable instructions to perform the steps of the method provided in the first aspect.

[0055] In a fourth aspect, an embodiment of the present application further provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the method provided in the first aspect are executed.

[0056] The beneficial effects of this application are:

[0057] The embodiment of the present application provides a photovoltaic power generation system control method, device, power optimizer and storage medium, the method comprising: obtaining an input current and input voltage of a power optimizer; obtaining actual input power according to the input voltage and input current; obtaining output power according to the actual input power and a first mapping curve generated in advance; wherein the first mapping curve is used to indicate the corresponding relationship between the output voltage and the output power of the power optimizer, and the first mapping curve comprises: a first voltage segment linear power curve and a second voltage segment linear power curve, wherein the voltage corresponding to the second voltage segment is higher than the voltage corresponding to the first voltage segment; outputting a bus voltage corresponding to the output power to a subsequent photovoltaic inverter, so that the subsequent photovoltaic inverter determines the target maximum power according to the bus voltage. In this solution, the external characteristics of the power-voltage relationship curve of the high- and low-voltage sections of the power optimizer are adjusted, so that when the first MPPT unit is disturbed at a point near Vo1 (or Vo4), the output power can be obtained based on the actual input power and the pre-generated first mapping curve, and the bus voltage corresponding to the output power is output to the subsequent photovoltaic inverter, so that the subsequent photovoltaic inverter disturbs the bus voltage to obtain the target maximum power of the photovoltaic power generation system, and effectively solves the problem that when the first MPPT unit in the power optimizer is disturbed at a point near Vo1 (or Vo4), the output power Po of the power optimizer jumps from constant power to 0, so that the power optimizer can automatically adapt to the disturbance voltage changes of the subsequent connected "photovoltaic inverter", thereby effectively balancing the competitive relationship between the "power optimizer" and the "photovoltaic inverter" to avoid mismatch oscillations. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0059] Figure 1 A schematic diagram of the structure of a photovoltaic power generation system provided in an embodiment of the present application;

[0060] Figure 2 A schematic diagram of the structure of a power optimizer provided in an embodiment of the present application;

[0061] Figure 3 A schematic diagram of a photovoltaic power generation system control method provided in an embodiment of the present application;

[0062] Figure 4 It is a schematic diagram of an external characteristic curve of output voltage and output power of a power optimizer in the prior art;

[0063] Figure 5 A schematic diagram of an external characteristic curve of output voltage and output power of a power optimizer provided in an embodiment of the present application;

[0064] Figure 6 A schematic flow chart of another photovoltaic power generation system control method provided in an embodiment of the present application;

[0065] Figure 7 A schematic diagram of the working principle of the MPPT unit and the output voltage limiting power loop in a power optimizer in a photovoltaic power generation system control method provided in an embodiment of the present application;

[0066] Figure 8 A schematic diagram of the overall process of a photovoltaic power generation system control method provided in an embodiment of the present application;

[0067] Fig. 9 A schematic diagram of the structure of a photovoltaic power generation system control device provided in an embodiment of the present application.

[0068] Icon: 100-photovoltaic power generation system; 101-power optimizer; 102-photovoltaic inverter. DETAILED DESCRIPTION

[0069] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the drawings in the present application only serve the purpose of explanation and description and are not used to limit the scope of protection of the present application. In addition, it should be understood that the schematic drawings are not drawn in real proportion. The flowchart used in this application shows the operations implemented according to some embodiments of the present application. It should be understood that the operations of the flowchart can be implemented out of sequence, and the steps without logical context can be reversed in order or implemented simultaneously. In addition, those skilled in the art can add one or more other operations to the flowchart under the guidance of the content of the present application, or remove one or more operations from the flowchart.

[0070] In addition, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0071] It should be noted that the term "comprising" will be used in the embodiments of the present application to indicate the existence of the features declared thereafter, but does not exclude the addition of other features.

[0072] First of all, before specifically describing the technical solution provided by the present application, the working principle of the MPPT unit involved in the present application is briefly described.

[0073] The working principle of the MPPT unit: Real-time detection of the power generation voltage and current of the photovoltaic panel, and by measuring the changes in the output power and voltage of the photovoltaic panel before and after the disturbance, to determine the disturbance direction of the next cycle. When the disturbance direction is correct, the output power of the photovoltaic panel increases, and the next cycle continues to disturb in the same direction. Otherwise, it disturbs in the opposite direction. In this way, disturbance and observation are repeated to achieve the tracking of the maximum power point of the photovoltaic panel.

[0074] Secondly, the technical problem to be solved by this application is briefly described.

[0075] In the prior art, "power optimizers" and "photovoltaic inverters" are designed and manufactured by different manufacturers, and only the "power optimizer" or "photovoltaic inverter" in the photovoltaic power generation system is considered to perform maximum power point tracking according to the power-voltage characteristic curve in the photovoltaic power generation system, so that the photovoltaic power generation system can operate at the maximum power point to fully utilize solar energy resources and achieve the purpose of improving the energy conversion efficiency of the photovoltaic power generation system.

[0076] However, when a "power optimizer" and a "photovoltaic inverter" are both installed in a photovoltaic power generation system, the DC / DC units of the MPPT in the "power optimizer" and the "photovoltaic inverter" are trying to find their respective maximum power points through disturbance strategies, that is, the competitive relationship between the "power optimizer" and the "photovoltaic inverter" may cause mismatch oscillations.

[0077] Therefore, it is urgent to propose a power regulation method with an adaptive coordination strategy to solve the problem that when the "power optimizer" and the "photovoltaic inverter" are cascaded, whether the subsequent "photovoltaic inverter" has the MPPT function or not, it can effectively balance the competition relationship between the "power optimizer" and the "photovoltaic inverter" to avoid mismatch oscillation.

[0078] The inventive concept of the present application is to adjust the power-voltage relationship curves of the high- and low-voltage sections of the power optimizer so that the "power optimizer" in the photovoltaic power generation system can automatically adapt to the power changes of the subsequent connected "photovoltaic inverter" when seeking the maximum power point, thereby effectively balancing the competitive relationship between the "power optimizer" and the "photovoltaic inverter" to avoid mismatch oscillations.

[0079] As follows, the specific implementation steps and beneficial effects of the photovoltaic power generation system method provided by the present application will be described through multiple specific embodiments.

[0080] Figure 1 A schematic diagram of the structure of a photovoltaic power generation system provided in an embodiment of the present application; Figure 1 As shown, the photovoltaic power generation system 100 includes: photovoltaic panels (PV-1, ..., PV-n) electrically connected in sequence, at least one power optimizer 101, and a photovoltaic inverter 102.

[0081] like Figure 1 As shown, the embodiment of the present application provides a distributed photovoltaic power generation system, the power optimizer 101 adopts a multi-channel isolation boost solution, multiple independent MPPTs, tracks the maximum power of each photovoltaic panel, has high conversion efficiency, and outputs parallel networking.

[0082] For example, in a photovoltaic power generation system 100, photovoltaic panels (PV-1, ..., PV-n) are connected to a power optimizer 101, and the photovoltaic panels input the generated voltage and current to the power optimizer, and each power optimizer 101 uses an input independent MPPT operation so that the power optimizer 101 can detect the power generation voltage of the photovoltaic panels in real time, and obtain the actual output power of the power optimizer 101 according to the photovoltaic power generation system control method provided in the present application. Multiple power optimizers output their respective output voltages in parallel to form a DC bus voltage (DC+, DC-), and the photovoltaic inverter 102 obtains the target maximum power of the photovoltaic power generation system 100 based on the DC bus voltage. Finally, the photovoltaic inverter 102 converts the DC voltage corresponding to the target maximum power into an AC voltage and outputs it to the grid.

[0083] Figure 2 A schematic diagram of the structure of a power optimizer provided in an embodiment of the present application; Figure 2 As shown, the power optimizer 101 includes: a processor 201 and a memory 202 .

[0084] The processor 201 and the memory 202 are directly or indirectly electrically connected to each other to achieve data transmission or interaction. For example, the electrical connection can be achieved through one or more communication buses or signal lines.

[0085] The processor 201 may be an integrated circuit chip having the ability to process signals. The processor 201 may be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc. The methods, steps, and logic diagrams disclosed in the embodiments of the present invention may be implemented or executed. The general-purpose processor may be a microprocessor or any conventional processor.

[0086] The memory 202 can be, but is not limited to, a random access memory (RAM), a read only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable read-only memory (EEPROM), etc.

[0087] The memory 202 is used to store programs, and the processor 201 calls the programs stored in the memory 202 to execute the photovoltaic power generation system control method provided in the following embodiments.

[0088] Understandably, Figure 2 The structure described is for illustration only. The power optimizer may also include Figure 2 More or fewer components as shown, or with Figure 2 Different configurations are shown. Figure 2 Each component shown in the figure can be implemented by hardware, software or a combination thereof.

[0089] The implementation principle and corresponding beneficial effects of the photovoltaic power generation system control method provided in the present application will be explained through a number of specific embodiments as follows.

[0090] Figure 3 A schematic diagram of a photovoltaic power generation system control method provided in an embodiment of the present application; the execution subject of the method may be the above Figure 1 and Figure 2 The power optimizer shown, Figure 3 As shown, the method may include:

[0091] S301 : Obtain input current and input voltage of a power optimizer.

[0092] S302: Obtain actual input power according to input voltage and input current.

[0093] refer to Figure 1 Under the irradiation of sunlight, the photovoltaic panels will generate voltage and current, which will be transmitted to the power optimizer through wires and used as the input voltage Uin and input current Iin of the power optimizer. The power optimizer calculates the actual input power Pin = Uin*Iin of the power optimizer based on the received input voltage Uin and input current Iin.

[0094] S303: Obtain output power according to actual input power and a pre-generated first mapping curve.

[0095] Among them, the first mapping curve is used to indicate the corresponding relationship between the output voltage and output power of the power optimizer, and the first mapping curve includes: a first voltage segment linear power curve and a second voltage segment linear power curve, wherein the voltage corresponding to the second voltage segment is higher than the voltage corresponding to the first voltage segment.

[0096] Here, the maximum limited power of the power optimizer is recorded as Pomax.

[0097] It should be noted that a brief explanation is given of the relationship between the output voltage Uo of the "power optimizer" and the bus voltage of the "photovoltaic inverter" in the photovoltaic power generation system.

[0098] 1. In this embodiment, a first MPPT unit is provided inside the power optimizer. The first MPPT unit disturbs the input voltage Uin to seek the maximum power point of the photovoltaic panel when it is working. According to the maximum power of the photovoltaic panel when it is working and the maximum limited power of the power optimizer, the output power Po and output voltage Uo of the "power optimizer" can be obtained.

[0099] 2. The power optimizer can detect its own output voltage Uo in real time, that is, the bus voltage at both ends of DC+ and DC- of the photovoltaic inverter. However, the "second MPPT unit" in the photovoltaic inverter will disturb the bus voltage at both ends of DC+ and DC-, causing the bus voltage to change in order to seek the target maximum power of the photovoltaic power generation system.

[0100] Figure 4 FIG. 1 is a schematic diagram of an external characteristic curve of output voltage and output power of a power optimizer in the prior art; Figure 4 As shown, in the prior art, the external characteristic curve between the output voltage Uo and the output power Po of the power optimizer is a constant power curve from Vo1 to Vo4, wherein the horizontal axis is the output voltage Uo of the power optimizer, and the vertical axis is the ratio of the output power Po of the power optimizer to the maximum limited power Pomax, i.e. Po / Pomax.

[0101] However, when the power optimizer detects that the bus voltage (DC+, DC-) of the photovoltaic inverter is currently disturbed at point Vo1 (or Vo4), further, when the MPPT unit in the power optimizer performs disturbance tracking of the maximum power point at point Vo1 (or Vo4), the output power Po will jump from constant power to 0, causing the power optimizer to enter the cutoff zone, and the downstream photovoltaic inverter will not be able to work normally, that is, the power optimizer and the photovoltaic inverter have a mismatch oscillation.

[0102] Therefore, the present application proposes to adjust the external characteristics of the power-voltage relationship curve of the high- and low-voltage sections of the power optimizer, which can effectively solve the problem that when the first MPPT unit in the power optimizer is disturbed at the point near Vo1 (or Vo4), the output power Po of the power optimizer jumps from constant power to 0, so that the power optimizer automatically adapts to the disturbance voltage changes of the "photovoltaic inverter" connected to the subsequent stage, thereby effectively balancing the competitive relationship between the "power optimizer" and the "photovoltaic inverter" and avoiding mismatch oscillations.

[0103] Based on the above analysis, in this embodiment, the power optimizer can obtain the output power Po of the power optimizer according to the relationship between its actual input power and the first mapping curve generated in advance.

[0104] S304: Outputting the bus voltage corresponding to the output power to the subsequent photovoltaic inverter, so that the subsequent photovoltaic inverter determines the target maximum power according to the bus voltage.

[0105] The bus voltage (DC+, DC-) corresponding to the output power refers to: the output voltage Uo corresponding to the output power Po of the power optimizer.

[0106] Based on the above embodiment, the power optimizer outputs the output voltage Uo corresponding to its own output power Po to the subsequent photovoltaic inverter, and the second MPPT unit in the subsequent photovoltaic inverter disturbs the bus voltage to obtain the target maximum power of the photovoltaic power generation system.

[0107] In summary, an embodiment of the present application provides a photovoltaic power generation system control method, the method comprising: obtaining an input current and an input voltage of a power optimizer; obtaining an actual input power based on the input voltage and the input current; obtaining an output power based on the actual input power and a first mapping curve generated in advance; wherein the first mapping curve is used to indicate the correspondence between the output voltage and the output power of the power optimizer, the first mapping curve comprising: a first voltage segment linear power curve and a second voltage segment linear power curve, wherein the voltage corresponding to the second voltage segment is higher than the voltage corresponding to the first voltage segment; outputting a bus voltage corresponding to the output power to a subsequent photovoltaic inverter, so that the subsequent photovoltaic inverter determines the target maximum power based on the bus voltage. In this solution, the external characteristics of the power-voltage relationship curve of the high- and low-voltage sections of the power optimizer are adjusted, so that when the first MPPT unit is disturbed at a point near Vo1 (or Vo4), the output power can be obtained based on the actual input power and the pre-generated first mapping curve, and the bus voltage corresponding to the output power is output to the subsequent photovoltaic inverter, so that the subsequent photovoltaic inverter disturbs the bus voltage to obtain the target maximum power of the photovoltaic power generation system, and effectively solves the problem that when the first MPPT unit in the power optimizer is disturbed at a point near Vo1 (or Vo4), the output power Po of the power optimizer jumps from constant power to 0, so that the power optimizer can automatically adapt to the disturbance voltage changes of the subsequent connected "photovoltaic inverter", thereby effectively balancing the competitive relationship between the "power optimizer" and the "photovoltaic inverter" to avoid mismatch oscillations.

[0108] The following embodiment will specifically explain how to obtain the output power according to the actual input power and the pre-generated first mapping curve.

[0109] Optionally, before obtaining the output power according to the actual input power and the pre-generated first mapping curve, the method further includes:

[0110] The corresponding relationship between the first voltage segment, the second voltage segment and the output power is adjusted respectively to obtain a first mapping curve, so that the power optimizer can obtain the output power according to the actual input power and the pre-generated voltage-power first mapping curve, thereby achieving the purpose of balancing the competitive relationship between the "power optimizer" and the "photovoltaic inverter" and avoiding mismatch oscillation.

[0111] Figure 5 A schematic diagram of an external characteristic curve of output voltage and output power of a power optimizer provided in an embodiment of the present application; Figure 5 As shown, the first mapping curve also includes: a third voltage segment and a constant power segment, wherein a voltage corresponding to the third voltage segment is higher than a voltage corresponding to the first voltage segment, and lower than a voltage corresponding to the second voltage segment.

[0112] The first voltage segment linear power curve is a linear curve in which power increases with increasing voltage or power decreases with decreasing voltage, and the second voltage segment linear power curve is a linear curve in which power decreases with increasing voltage or power increases with decreasing voltage.

[0113] 1. The first voltage segment is from Vo1 to V02. In the first voltage segment, the relationship between the output power Po of the power optimizer and the output voltage Uo is a positively correlated linear curve, that is, the output power Po of the power optimizer decreases as the output voltage Uo decreases. It can also be understood that the output power Po of the power optimizer increases as the output voltage Uo increases.

[0114] When the output voltage Uo detected by the power optimizer is within the first voltage segment Vo1 to V02, it can also be understood that the bus voltage currently disturbed by the second MPPT unit in the photovoltaic optimizer is within the first voltage segment Vo1 to V02. At this time, when the first MPPT unit in the power optimizer is disturbed within the first voltage segment, it will be found that the output power Po of the power optimizer decreases as the output voltage Uo decreases, which means that the current disturbance direction is wrong, and the next cycle is disturbed in the opposite direction. After multiple disturbances and observations, the maximum output power point of the power optimizer can be tracked.

[0115] 2. The second voltage segment is from Vo3 to V04. In the second voltage segment, the relationship between the output power Po of the power optimizer and the output voltage Uo is a negatively correlated linear curve, that is, the output power Po of the power optimizer decreases as the output voltage Uo increases. It can also be understood that the output power Po of the power optimizer increases as the output voltage decreases.

[0116] When the output voltage Uo detected by the power optimizer is within the second voltage segment Vo3 to V04, it can also be understood that the bus voltage currently disturbed by the second MPPT unit in the photovoltaic optimizer is within the second voltage segment Vo3 to V04. At this time, when the first MPPT unit in the power optimizer is disturbed in the second voltage segment, it will be found that the output power Po of the power optimizer decreases with the increase of the output voltage Uo, that is, it can be determined that the current disturbance direction is wrong, and the next cycle is disturbed in the opposite direction. After multiple disturbances and observations, the maximum output power point of the power optimizer can be tracked.

[0117] In this embodiment, the first voltage segment linear power curve and the second voltage segment linear power curve in the first mapping curve are used to avoid the output power Po of the first MPPT unit in the power optimizer jumping to 0 during the disturbance process. In this way, when the output voltage Uo exceeds the output voltage range, the protection or voltage limiting control mechanism of the power optimizer will be triggered.

[0118] 3. The third voltage segment is from Vo2 to V03. The third voltage segment is a constant power curve, that is, the output power Po of the power optimizer remains unchanged as the output voltage Uo increases (or decreases), and the output power Po of the power optimizer is a constant value.

[0119] When the output voltage Uo detected by the power optimizer is within the third voltage segment Vo2 to V03, it can also be understood that the bus voltage currently disturbed by the second MPPT unit in the photovoltaic optimizer is within the third voltage segment Vo2 to V03. At this time, when the first MPPT unit in the power optimizer is disturbed within the third voltage segment, it will be found that the output power Po of the power optimizer remains unchanged as the output voltage Uo increases, that is, the output power of the power optimizer can be determined based on the constant power of the third voltage segment and the actual input power of the power optimizer.

[0120] It should be noted that V01 and V04 must be included in the input range of the bus voltage (DC+, DC-) of the downstream photovoltaic inverter, otherwise it will affect the normal operation of the downstream photovoltaic inverter. The specific values ​​of V01 and V04 can be determined according to the input range of commonly used photovoltaic inverters. It is recommended to adapt to the input range requirements of most photovoltaic inverters. In addition, the slopes of the linear power curve of the first voltage segment and the linear power curve of the second voltage segment should not be set too steep to avoid oscillation.

[0121] Optionally, the step S303, obtaining the output power according to the actual input power and the pre-generated first mapping curve, includes:

[0122] If the bus voltage after the disturbance of the rear photovoltaic inverter is detected to be within the first voltage segment or the second voltage segment, the output power is obtained according to the linear power curve of the first voltage segment or the linear power curve of the second voltage segment.

[0123] Specifically, for example, if the power optimizer detects that the bus voltage (DC+, DC-) after the disturbance of the downstream photovoltaic inverter is Figure 5 In the first voltage segment Vo1 to V02, that is, the output voltage Uo of the power optimizer is Uo=V1, then according to the linear power curve of the first voltage segment, it can be read that the output power corresponding to the output voltage V1 of the power optimizer is Po=k*Pomax.

[0124] Similarly, if the bus voltage after the disturbance of the rear-stage photovoltaic inverter is detected to be within the second voltage segment, the output power is obtained according to the linear power curve of the second voltage segment.

[0125] In this embodiment, if the actual maximum photovoltaic input power is less than the maximum constant power value of the power optimizer, such as k is less than 1, the actual working area is the area below the intersection of the k value dotted line and the external characteristic. Since the k value must intersect with the first voltage segment linear power curve or the second voltage segment linear power curve, there is a maximum power interval. If it is detected that the bus voltage after the disturbance of the rear-stage photovoltaic inverter is running in the first voltage segment Vo1-Vo2 or the second voltage segment Vo3-Vo4, it can also be understood that the second MPPT unit disturbance in the rear-stage photovoltaic inverter flies out of the constant power interval. At this time, the power optimizer enters the high-voltage and low-voltage power limit segments, that is, the output power Po of the power optimizer can be obtained according to the first voltage segment linear power curve or the second voltage segment linear power curve, which limits the output power Po of the power optimizer.

[0126] Optionally, the above step S303, obtaining the output power according to the actual input power and the pre-generated first mapping curve, further includes:

[0127] If it is detected that the bus voltage after the disturbance of the rear photovoltaic inverter is within the third voltage section, the output power is obtained according to the constant power section of the third voltage section.

[0128] For example, if the power optimizer detects that the bus voltage (DC+, DC-) after the disturbance of the downstream photovoltaic inverter is Figure 5 In the third voltage segment Vo2 to V03, that is, the output voltage Uo of the power optimizer is V2, according to the linear power curve of the third voltage segment, it can be read that the output power corresponding to the output voltage V2 of the power optimizer is Pomax.

[0129] However, it is also necessary to judge and compare the actual input power Pin of the power optimizer and the maximum limited power Pomax to determine the final output power Po when the output voltage Uo of the power optimizer is V2.

[0130] In the first case, if the actual input power Pin is less than the maximum limited power Pomax of the power optimizer, the actual input power is used as the output power.

[0131] In the second case, if the actual input power is greater than or equal to the maximum limited power Pomax, the maximum limited power is used as the output power.

[0132] Among them, "the actual input power Pin of the power optimizer" and "the output power of the photovoltaic panel" are the same concept.

[0133] Usually, due to the influence of various factors such as weather, the actual output power of the photovoltaic panel may be greater than or less than the maximum limited power Pomax of the power optimizer. If the output power of the photovoltaic panel is greater than or equal to the maximum limited power Pomax of the power optimizer, the output power Po of the power optimizer is equal to the maximum limited power Pomax; if the maximum output capacity of the photovoltaic panel is less than the maximum limited power Pomax of the power optimizer (the ratio is less than 1), the output power Po of the power optimizer is equal to the maximum power of the photovoltaic panel, and the maximum power of the photovoltaic panel can be tracked by the first MPPT unit in the power optimizer.

[0134] In this embodiment, when the bus voltage after the disturbance of the subsequent photovoltaic inverter is detected and is within the third voltage segment Vo2-Vo3 (that is, when the output voltage of the power optimizer is between Vo2 and Vo3), the minimum value between the "actual input power" and the "maximum limited power Pomax" of the power optimizer is used as the output power Po of the power optimizer.

[0135] Figure 6 A schematic flow chart of another photovoltaic power generation system control method provided in an embodiment of the present application; optionally, as Figure 6 As shown, after the output power is obtained according to the actual input power and the pre-generated first mapping curve in the above step 303, the following is further included:

[0136] S601. Determine a first given current according to a maximum power point and a given voltage corresponding to the maximum power point.

[0137] The maximum power point is a maximum power point unit in the power optimizer, which is obtained by perturbing the input voltage and the input current.

[0138] It should be noted that the maximum power point unit can also be understood as the first MPPT unit set in the power optimizer. The input voltage and input current of the power optimizer are the voltage and current generated by the photovoltaic panel.

[0139] Figure 7 A schematic diagram of the working principle of the MPPT unit and the output voltage limiting power loop in the power optimizer in a photovoltaic power generation system control method provided in an embodiment of the present application is shown in FIG. Figure 7 As shown, the first MPPT unit disturbs the voltage and current generated by the photovoltaic panel, and tracks the maximum power point of the photovoltaic panel and the given voltage Vin* corresponding to the maximum power point, and transmits the given voltage Vin* to the input voltage inner loop, so that the first given current I1* can be determined according to the given voltage Vin*.

[0140] S602: Determine a second given current according to the output power and the output voltage corresponding to the output power.

[0141] In this embodiment, the output power Po corresponding to the output voltage Uo is obtained according to the relationship curve between the output power Po and the output voltage Uo of the power optimizer, and the second given current I2* is calculated by the output voltage power limiting loop.

[0142] S603: Obtain a minimum given current according to the first given current and the second given current.

[0143] S604: Use the minimum given current to adjust the duty cycle of the power optimizer.

[0144] On the basis of the above embodiment, for example, the first given current I1* and the second given current I2* are compared, the minimum value of the first given current I1* and the second given current I2* is used as the minimum given current Imin*, and the minimum given current Imin* is transmitted to the current inner loop as a reference given.

[0145] Usually, a MOSFET is also provided in the power optimizer, so the current loop controller can use the minimum given current to achieve a change in the duty cycle D of the MOSFET, thereby generating a current disturbance and achieving the purpose of stabilizing the output voltage.

[0146] Figure 8 The overall flow diagram of a photovoltaic power generation system control method provided in an embodiment of the present application; optionally, as Figure 7 As shown, the method includes:

[0147] S801. Obtain input current and input voltage of a power optimizer.

[0148] S802: Obtain actual input power according to input voltage and input current.

[0149] S803: Adjust the corresponding relationship between the first voltage segment, the second voltage segment and the output power respectively to obtain a first mapping curve.

[0150] S804: If it is detected that the bus voltage of the downstream photovoltaic inverter after the disturbance is in the first voltage segment or the second voltage segment, the output power is obtained according to the linear power curve of the first voltage segment or the linear power curve of the second voltage segment.

[0151] S805: If it is detected that the bus voltage after the disturbance of the rear photovoltaic inverter is within the third voltage range, the minimum value between the actual input power of the power optimizer and the maximum limited power is used as the output power.

[0152] Optionally, the specific implementation steps of the overall process of the photovoltaic power generation system control method and the beneficial effects produced have been described in detail in the previous specific embodiments, and will not be repeated here.

[0153] Fig. 9 A schematic diagram of the structure of a photovoltaic power generation system control device provided in an embodiment of the present application; Fig. 9 As shown, the photovoltaic power generation system control device includes: an acquisition module 901 , a processing module 902 , and a determination module 903 .

[0154] An acquisition module 901 is used to acquire an input current and an input voltage of a power optimizer;

[0155] The processing module 902 is used to obtain the actual input power according to the input voltage and the input current; and obtain the output power according to the actual input power and a pre-generated first mapping curve; wherein the first mapping curve is used to indicate the corresponding relationship between the output voltage and the output power of the power optimizer, and the first mapping curve includes: a first voltage segment linear power curve and a second voltage segment linear power curve, wherein the voltage corresponding to the second voltage segment is higher than the voltage corresponding to the first voltage segment;

[0156] The determination module 903 is used to output the bus voltage corresponding to the output power to the subsequent photovoltaic inverter, so that the subsequent photovoltaic inverter determines the target maximum power according to the bus voltage.

[0157] Optionally, the first mapping curve further includes: a third voltage segment and a constant power segment, wherein a voltage corresponding to the third voltage segment is higher than a voltage corresponding to the first voltage segment and lower than a voltage corresponding to the second voltage segment;

[0158] The linear power curve in the first voltage segment is a linear curve in which power increases as voltage increases, and the linear power curve in the second voltage segment is a linear curve in which power decreases as voltage increases.

[0159] Optionally, the processing module 902 is further configured to:

[0160] If the bus voltage after the disturbance of the rear photovoltaic inverter is detected to be within the first voltage segment or the second voltage segment, the output power is obtained according to the linear power curve of the first voltage segment or the linear power curve of the second voltage segment.

[0161] Optionally, the processing module 902 is further configured to:

[0162] If it is detected that the bus voltage after the disturbance of the rear-stage photovoltaic inverter is within the third voltage section, the output power is obtained according to the constant power section of the third voltage section.

[0163] Optionally, the processing module 902 is further configured to:

[0164] If the actual input power is less than or equal to the maximum limited power of the power optimizer, the actual input power is used as the output power.

[0165] Optionally, the processing module 902 is further configured to:

[0166] If the actual input power is greater than the maximum limited power, the maximum limited power will be used as the output power.

[0167] Optionally, the device further comprises: an adjustment module;

[0168] The adjustment module is used to adjust the corresponding relationship between the first voltage segment, the second voltage segment and the output power respectively to obtain a first mapping curve.

[0169] Optionally, the adjustment module is further configured to:

[0170] Adjusting the corresponding relationship between the first voltage segment and the output power to a linear relationship in which the power increases as the voltage increases;

[0171] The corresponding relationship between the second voltage segment and the output power is adjusted to a linear relationship in which the power decreases as the voltage increases.

[0172] Optionally, the processing module 902 is further configured to:

[0173] Determine a first given current according to a maximum power point and a given voltage corresponding to the maximum power point; wherein the maximum power point is a maximum power point unit in a power optimizer, obtained by perturbing an input voltage and an input current; determine a second given current according to an output power and an output voltage corresponding to the output power; obtain a minimum given current according to the first given current and the second given current;

[0174] The device also includes: a regulating module, which is used to use a minimum given current to regulate the duty cycle of the power optimizer.

[0175] The above-mentioned device is used to execute the method provided by the aforementioned embodiment, and its implementation principle and technical effect are similar, which will not be repeated here.

[0176] The above modules may be one or more integrated circuits configured to implement the above methods, such as one or more application specific integrated circuits (ASIC), or one or more digital singnal processors (DSP), or one or more field programmable gate arrays (FPGA). For another example, when a module is implemented in the form of a processing element scheduling program code, the processing element may be a general-purpose processor, such as a central processing unit (CPU) or other processor that can call program code. For another example, these modules may be integrated together and implemented in the form of a system-on-a-chip (SOC).

[0177] Optionally, the present invention also provides a program product, such as a computer-readable storage medium, comprising a program, which is used to execute the above method embodiment when executed by a processor.

[0178] In the several embodiments provided by the present invention, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0179] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0180] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0181] The above-mentioned integrated unit implemented in the form of a software functional unit can be stored in a computer-readable storage medium. The above-mentioned software functional unit is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor (English: processor) to perform some steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (English: Read-Only Memory, abbreviated: ROM), random access memory (English: Random Access Memory, abbreviated: RAM), disk or optical disk and other media that can store program codes.

Claims

1. A photovoltaic power generation system control method, It is characterized in that Power optimizers used in photovoltaic power generation systems include: Obtain input current and input voltage of the power optimizer; Obtaining actual input power according to the input voltage and the input current; The output power is obtained according to the actual input power and a pre-generated first mapping curve; wherein the first mapping curve is used to indicate the corresponding relationship between the output voltage and the output power of the power optimizer, and the first mapping curve includes: a first voltage segment linear power curve corresponding to the first voltage segment and a second voltage segment linear power curve corresponding to the second voltage segment, wherein the voltage corresponding to the second voltage segment is higher than the voltage corresponding to the first voltage segment; Outputting the bus voltage corresponding to the output power to a subsequent photovoltaic inverter, so that the subsequent photovoltaic inverter determines a target maximum power according to the bus voltage; Wherein, the first mapping curve further includes: a third voltage segment constant power segment corresponding to the third voltage segment, wherein the voltage corresponding to the third voltage segment is higher than the voltage corresponding to the first voltage segment, and lower than the voltage corresponding to the second voltage segment; The linear power curve of the first voltage segment is a linear curve in which power increases as voltage increases or power decreases as voltage decreases, and the linear power curve of the second voltage segment is a linear curve in which power decreases as voltage increases or power increases as voltage decreases; The step of obtaining the output power according to the actual input power and a pre-generated first mapping curve includes: If the bus voltage of the rear photovoltaic inverter after disturbance is detected to be within the first voltage segment or the second voltage segment, the output power is obtained according to the linear power curve of the first voltage segment or the linear power curve of the second voltage segment.

2. The method according to claim 1, It is characterized in that Also includes: If it is detected that the bus voltage of the rear-stage photovoltaic inverter after disturbance is within the third voltage section, the output power is obtained according to the constant power section of the third voltage section.

3. The method according to claim 2, It is characterized in that The step of obtaining the output power according to the third voltage section and the constant power section comprises: If the actual input power is less than or equal to the maximum limited power of the power optimizer, the actual input power is used as the output power.

4. The method according to claim 3, It is characterized in that Also includes: If the actual input power is greater than the maximum limited power, the maximum limited power is used as the output power.

5. The method according to any one of claims 1 to 4, It is characterized in that Before obtaining the output power according to the actual input power and the pre-generated first mapping curve, the method further includes: The corresponding relationships between the first voltage segment, the second voltage segment and the output power are adjusted respectively to obtain the first mapping curve.

6. A photovoltaic power generation system control device, It is characterized in that The device comprises: an acquisition module, a processing module, and a determination module; The acquisition module is used to acquire the input current and input voltage of the power optimizer; The processing module is used to obtain the actual input power according to the input voltage and the input current; and obtain the output power according to the actual input power and a pre-generated first mapping curve; wherein the first mapping curve is used to indicate the corresponding relationship between the output voltage and the output power of the power optimizer, and the first mapping curve includes: a first voltage segment linear power curve corresponding to the first voltage segment and a second voltage segment linear power curve corresponding to the second voltage segment, wherein the voltage corresponding to the second voltage segment is higher than the voltage corresponding to the first voltage segment; wherein the first mapping curve also includes: a third voltage segment constant power segment corresponding to the third voltage segment, wherein the voltage corresponding to the third voltage segment is higher than the voltage corresponding to the first voltage segment and lower than the voltage corresponding to the second voltage segment; The linear power curve of the first voltage segment is a linear curve in which power increases as voltage increases or power decreases as voltage decreases, and the linear power curve of the second voltage segment is a linear curve in which power decreases as voltage increases or power increases as voltage decreases; If the bus voltage after the disturbance of the downstream photovoltaic inverter is detected to be within the first voltage segment or the second voltage segment, the output power is obtained according to the linear power curve of the first voltage segment or the linear power curve of the second voltage segment; The determination module is used to output the bus voltage corresponding to the output power to the subsequent photovoltaic inverter, so that the subsequent photovoltaic inverter determines the target maximum power according to the bus voltage.

7. A power optimizer, It is characterized in that include: A processor, a storage medium and a bus, wherein the storage medium stores machine-readable instructions executable by the processor, and when the power optimizer is running, the processor communicates with the storage medium via the bus, and the processor executes the machine-readable instructions to perform the steps of any method as described in claims 1-5.

8. A computer-readable storage medium, It is characterized in that The storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are executed.

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