Control method of photovoltaic energy storage device, photovoltaic energy storage device and readable storage medium

Abstract

The application discloses a control method of a photovoltaic energy storage device, the photovoltaic energy storage device and a storage medium. The method comprises the following steps: acquiring a first output voltage of a photovoltaic panel and a second output voltage of a second end of the photovoltaic energy storage device; determining a first follow-up voltage and a second follow-up voltage corresponding to the first output voltage; determining a PV curve of the photovoltaic energy storage device according to the first follow-up voltage, the second follow-up voltage and maximum compensation power of the photovoltaic energy storage device; determining a target discharge power of the photovoltaic energy storage device based on the PV curve and the second output voltage; and controlling the photovoltaic energy storage device to discharge to compensate power of a photovoltaic inverter according to the target discharge power. According to the method, the PV curve of the photovoltaic energy storage device is determined according to the first follow-up voltage, the second follow-up voltage and the maximum compensation power of the photovoltaic energy storage device, so that the number of times of restart of the photovoltaic inverter can be reduced to the maximum extent.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular to a control method for a photovoltaic energy storage device, a photovoltaic energy storage device, and a computer-readable storage medium. Background Technology

[0002] In photovoltaic (PV) energy storage or PV power supply systems, PV panels can feed power to the grid through PV inverters. When the electricity generated by the PV panels cannot meet the load demand, the load needs to draw power from the grid, resulting in additional electricity costs for the user. To solve this problem, PV energy storage devices are needed for power compensation. These added PV energy storage devices need to work in conjunction with the PV inverter to maximize PV power generation through maximum power point tracking (MPPT). If the PV energy storage device outputs a constant power, low output voltage or power from the PV panels can easily cause the PV inverter to restart, affecting its MPPT performance and reducing the stability of the PV energy storage or PV power supply system.

[0003] Therefore, how to prevent the photovoltaic inverter from restarting when the output voltage or output power of the photovoltaic panel is too low has become an urgent problem to be solved. Summary of the Invention

[0004] This application provides a control method for a photovoltaic energy storage device, a photovoltaic energy storage device, and a computer-readable storage medium, which solves the problem that photovoltaic inverters are prone to restarting when the output voltage or output power of the photovoltaic panel is too low.

[0005] In a first aspect, this application provides a control method for a photovoltaic energy storage device, the method comprising: The following steps are taken: 1. Obtain the input voltage at the first terminal of the photovoltaic energy storage device and the output voltage at the second terminal of the photovoltaic energy storage device; 2. Determine the first following voltage and the second following voltage corresponding to the input voltage; 3. Determine the PV curve of the photovoltaic energy storage device's discharge based on the first following voltage, the second following voltage, and the maximum compensation power of the photovoltaic energy storage device for the photovoltaic inverter; 4. Determine the target discharge power of the photovoltaic energy storage device based on the PV curve and the output voltage; 5. Control the photovoltaic energy storage device to discharge according to the target discharge power to compensate the photovoltaic inverter for power, wherein the output power at the second terminal is the sum of the input power at the first terminal and the discharge power of the photovoltaic energy storage device.

[0006] The above control method determines the first and second follower voltages corresponding to the input voltage of the photovoltaic energy storage device, determines the PV curve of the photovoltaic energy storage device discharge based on the first and second follower voltages and the maximum compensation power of the photovoltaic energy storage device, and controls the photovoltaic energy storage device to discharge based on the PV curve. This allows the photovoltaic energy storage device to dynamically connect the working voltage range and power range of the photovoltaic panel through the PV curve, minimizing the number of times the photovoltaic inverter restarts when the output voltage or output power of the photovoltaic panel is too low.

[0007] Secondly, this application also provides a photovoltaic energy storage device, which includes a memory and a controller; The memory is used to store computer programs; The controller is used to execute the computer program and, when executing the computer program, implement the control method for the photovoltaic energy storage device as described above.

[0008] Thirdly, this application also provides a computer-readable storage medium storing a computer program that, when executed by a controller, enables the controller to implement the control method for the photovoltaic energy storage device as described above. Attached Figure Description

[0009] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 This is a schematic diagram of the structure of a photovoltaic power supply system provided in an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a photovoltaic energy storage device provided in an embodiment of this application; Figure 3 This is a schematic flowchart illustrating a control method for a photovoltaic energy storage device provided in an embodiment of this application; Figure 4 This is a schematic diagram of a PV curve provided in an embodiment of this application; Figure 5 This is a schematic flowchart illustrating a sub-step for determining the following voltage, provided in an embodiment of this application. Figure 6 This is a schematic diagram of a voltage follower provided in an embodiment of this application; Figure 7 This is a schematic flowchart illustrating a sub-step for determining a target following voltage, provided in an embodiment of this application. Figure 8 This is a schematic flowchart illustrating a sub-step for determining a first sub-PV curve, provided in an embodiment of this application. Figure 9 This is a schematic flowchart illustrating a sub-step for determining a second sub-PV curve, provided in an embodiment of this application. Figure 10 This is a schematic flowchart illustrating a sub-step for determining a third sub-PV curve, provided in an embodiment of this application. Detailed Implementation

[0011] The technical solutions of 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, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0012] The flowchart shown in the attached diagram is for illustrative purposes only and does not necessarily include all content and operations / steps, nor does it necessarily have to be performed in the order described. For example, some operations / steps can be broken down, combined, or partially merged, so the actual execution order may change depending on the actual situation.

[0013] It should be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0014] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0015] This application provides a control method for a photovoltaic energy storage device, a photovoltaic energy storage device, and a computer-readable storage medium. The control method for the photovoltaic energy storage device can be applied to the device. By determining a first follower voltage and a second follower voltage corresponding to the input voltage of the photovoltaic energy storage device, and determining the PV curve of the photovoltaic energy storage device's discharge based on the first follower voltage, the second follower voltage, and the maximum compensation power of the device, the method controls the photovoltaic energy storage device to discharge based on the PV curve. This allows the photovoltaic energy storage device to dynamically connect the operating voltage range and power range of the photovoltaic panel through the PV curve, minimizing the number of times the photovoltaic inverter restarts when the output voltage or output power of the photovoltaic panel is too low.

[0016] Please see Figure 1, Figure 1 This is a schematic diagram of the structure of a photovoltaic power supply system 10 provided in an embodiment of this application, as shown below. Figure 1 As shown, the photovoltaic power supply system 10 may include a photovoltaic panel 11, a photovoltaic inverter 12, and a photovoltaic energy storage device 13. The photovoltaic energy storage device 13 is connected to both the photovoltaic panel 11 and the photovoltaic inverter 12. The photovoltaic energy storage device 13 is equipped with a DC bus (such as...). Figure 1 (BUS1+ / BUS1-), the photovoltaic panel 11 is connected to the DC bus via the first end of the photovoltaic energy storage device 13, and the photovoltaic inverter 12 is connected to the DC bus via the second end of the photovoltaic energy storage device 13.

[0017] It should be noted that in other embodiments, the DC bus can also be located outside the photovoltaic energy storage device 13. In this case, the photovoltaic panel 11 can be connected to the photovoltaic inverter 12 via the DC bus, and the photovoltaic energy storage device 13 can be connected to both the photovoltaic panel 11 and the photovoltaic inverter 12 via the DC bus. It is understood that, in this case, the first end and the second end of the photovoltaic energy storage device 13 can be the same end.

[0018] It should be noted that the photovoltaic panel 11 is used to convert solar energy into direct current and output it to the photovoltaic inverter 12 and / or photovoltaic energy storage device 13, wherein the photovoltaic inverter 12 is used to convert the received direct current into alternating current.

[0019] For example, the photovoltaic energy storage device 13 can be a mobile energy storage device, a home energy storage device, or an energy storage device installed in a vehicle.

[0020] like Figure 1 As shown, the photovoltaic energy storage device 13 is used to output electrical energy to the photovoltaic inverter 12. The AC side of the photovoltaic inverter 12 is connected to the AC bus (e.g., Figure 1 The photovoltaic energy storage device 13 (BUS2+ / BUS12-) is connected to the power grid 15. The output power from the second terminal of the photovoltaic energy storage device 13 is converted from AC to DC by the photovoltaic inverter 12 and then supplies power to the load 14 connected to the AC bus. The load 14 can be an electrical appliance. It should be noted that the output power of the photovoltaic energy storage device 13 can be provided by the photovoltaic panel 11 or by the battery inside the photovoltaic energy storage device 13.

[0021] For example, the photovoltaic inverter 12 may include an MPPT (Maximum Power Point Tracking) circuit 121 and an INV (Inverter) circuit 122. The first terminal of the MPPT circuit 121 is connected to the second terminal of the photovoltaic energy storage device 13, and the second terminal of the MPPT circuit 121 is connected to the first terminal of the INV circuit 122. The first terminal of the INV circuit 122 is connected to the load 14 and the power grid 15 via an AC bus. The MPPT circuit 121 is used to regulate the output voltage of the photovoltaic panel 11 to achieve maximum power point tracking. The INV circuit 122 is used to convert direct current (DC) to alternating current (AC).

[0022] like Figure 1 As shown, the photovoltaic energy storage device 13 may include an energy storage circuit 130, a DC-DC conversion circuit 131, and a controller 132. The first terminal of the DC-DC conversion circuit 131 is connected to the photovoltaic panel 11 and the photovoltaic inverter 12 via a DC bus, and the second terminal of the DC-DC conversion circuit 131 is connected to the energy storage circuit 130.

[0023] For example, the energy storage circuit 130 may include a battery for storing electrical energy when the photovoltaic panel 11 outputs electrical energy, and for outputting electrical energy to the photovoltaic inverter 12 when the photovoltaic panel 11 is not outputting electrical energy. The DC-DC conversion circuit 131 is used to convert the voltage of the electrical energy output from the photovoltaic panel 11 and to convert the voltage of the electrical energy output from the energy storage circuit 130. The controller 132 is connected to the DC-DC conversion circuit 131 and the energy storage circuit 130 to control their operation. In this application, the controller 132 is used to execute the control method of the photovoltaic energy storage device described in any of the embodiments of this application.

[0024] It should be noted that in some embodiments, the energy storage circuit 130 may also be located outside the photovoltaic energy storage device 13. In this case, the photovoltaic energy storage device 13 may include an energy storage interface, and the energy storage circuit 130, as an independent energy storage device, can be connected to the photovoltaic energy storage device 13 through this energy storage interface.

[0025] Please see Figure 2 , Figure 2 This is a schematic diagram of the structure of a photovoltaic energy storage device 13 provided in an embodiment of this application, as shown below. Figure 2 As shown, the photovoltaic energy storage device 13 may include an energy storage circuit 130, a DC-DC conversion circuit 131, a controller 132, and a memory 133.

[0026] The controller 132 can be connected to the energy storage circuit 130, the DC-DC conversion circuit 131, and the memory 133 via a bus, such as an Inter-integrated Circuit (I2C) bus or any suitable communication bus. The controller 132 provides computing and control capabilities to support the operation of the entire photovoltaic energy storage device 13.

[0027] The controller 132 can be a Central Processing Unit (CPU), or it can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor, or it can be any conventional processor.

[0028] In the embodiments of this application, Figure 1 and Figure 2 When the controller 132 executes the relevant computer program, it can perform the following steps: The process involves: acquiring the input voltage at the first terminal of the photovoltaic energy storage device and the output voltage at the second terminal of the photovoltaic energy storage device; determining the first and second follower voltages corresponding to the input voltage; determining the PV curve of the photovoltaic energy storage device's discharge based on the first and second follower voltages and the maximum compensation power of the photovoltaic energy storage device for the photovoltaic inverter; determining the target discharge power of the photovoltaic energy storage device based on the PV curve and the output voltage; and controlling the discharge of the photovoltaic energy storage device according to the target discharge power to compensate the photovoltaic inverter for power loss. The output power at the second terminal is the sum of the input power at the first terminal and the discharge power of the photovoltaic energy storage device.

[0029] In one embodiment, when determining the first follower voltage and the second follower voltage corresponding to the input voltage, the controller 132 is configured to: The target following voltage is determined based on the input voltage; the first following voltage and the second following voltage are determined based on the target following voltage, wherein the first following voltage is less than or equal to the target following voltage, and the second following voltage is greater than or equal to the target following voltage.

[0030] In one embodiment, when the controller 132 determines the first follower voltage and the second follower voltage based on the target follower voltage, it is configured to: When the target following voltage remains stable, the first following voltage and the second following voltage are controlled to be equal to the target following voltage; when the target following voltage decreases, the voltage decrease rate of the first following voltage is controlled to be greater than the voltage decrease rate of the second following voltage; when the target following voltage increases, the voltage increase rate of the second following voltage is controlled to be greater than the voltage increase rate of the first following voltage.

[0031] In one embodiment, when implementing the determination of the target following voltage based on the input voltage, the controller 132 is configured to: The input voltage is determined as the initial following voltage; the initial following voltage is limited according to the maximum and minimum operating voltages of the photovoltaic inverter to obtain the target following voltage.

[0032] In one embodiment, when the controller 132 determines the PV curve of the photovoltaic energy storage device discharge based on the first follower voltage, the second follower voltage, and the maximum compensation power of the photovoltaic energy storage device to the photovoltaic inverter, it is configured to: Determine the first sub-PV curve of the PV curve; the discharge power on the first sub-PV curve is positively correlated with the discharge voltage and the maximum discharge voltage is the first following voltage; determine the second sub-PV curve of the PV curve; the discharge voltage range of the second sub-PV curve is between the first following voltage and the second following voltage, and the discharge power on the second sub-PV curve is equal to the maximum compensation power; determine the third sub-PV curve of the PV curve; the discharge power on the third sub-PV curve is negatively correlated with the discharge voltage and the maximum discharge voltage is the second following voltage; based on the first sub-PV curve, the second sub-PV curve, and the third sub-PV curve, determine the PV curve.

[0033] In one embodiment, when implementing the determination of the first sub-PV curve of the PV curve, the controller 132 is used to implement: Determine the minimum discharge voltage corresponding to the minimum discharge power of the photovoltaic energy storage device; determine the power change slope of the first sub-PV curve based on the minimum discharge voltage, minimum discharge power, maximum compensation power, and first follower voltage; generate the first sub-PV curve based on the power change slope of the first sub-PV curve.

[0034] In one embodiment, when implementing the determination of the third sub-PV curve of the PV curve, the controller 132 is used to implement: Determine the maximum discharge voltage corresponding to the minimum discharge power of the photovoltaic energy storage device; determine the power change slope of the third sub-PV curve based on the maximum compensation power, the second follower voltage, the maximum discharge voltage, and the minimum discharge power; generate the third sub-PV curve based on the power change slope of the third sub-PV curve.

[0035] In one embodiment, the AC side of the photovoltaic inverter is connected to the power grid via an AC bus, and the output power from the second end of the photovoltaic energy storage device is converted from AC to DC by the photovoltaic inverter to supply power to the load connected to the AC bus; the controller 132 is also used to implement: Determine the first power output from the power grid to the AC bus; based on the first power, determine the maximum compensation power.

[0036] The following detailed description, in conjunction with the accompanying drawings, outlines some embodiments of this application. Unless otherwise specified, the following embodiments and features described herein can be combined with each other. Please refer to... Figure 3 , Figure 3 This is a schematic flowchart illustrating a control method for a photovoltaic energy storage device provided in an embodiment of this application. Figure 3 As shown, the control method of the photovoltaic energy storage device includes steps S101 to S105.

[0037] Step S101: Obtain the input voltage at the first end of the photovoltaic energy storage device and the output voltage at the second end of the photovoltaic energy storage device.

[0038] For example, when acquiring the input voltage at the first terminal and the output voltage at the second terminal of the photovoltaic energy storage device, a voltage sampling circuit can be used to collect the input voltage at the first terminal and the output voltage at the second terminal, respectively. The input voltage can be expressed as V. pv The output voltage can be expressed as V. out .

[0039] It should be noted that the input voltage at the first end of the photovoltaic energy storage device refers to the output voltage of the photovoltaic panel; the output voltage at the second end of the photovoltaic energy storage device refers to the output voltage of the DC-DC conversion circuit in the photovoltaic energy storage device. This output voltage is also the input voltage of the MPPT circuit in the photovoltaic inverter.

[0040] Step S102: Determine the first follower voltage and the second follower voltage corresponding to the input voltage.

[0041] For example, after obtaining the input voltage at the first terminal of the photovoltaic energy storage device, a first following voltage and a second following voltage corresponding to the input voltage can be determined. The first following voltage can be expressed as V. mid-L The second follower voltage can be expressed as V mid-R .

[0042] It should be noted that the first and second tracking voltages are used to track the output voltage of the photovoltaic panel. The first and second tracking voltages change at different rates. For example, when the output voltage of the photovoltaic panel decreases, the rate of decrease of the first tracking voltage is greater than that of the second tracking voltage; conversely, when the output voltage of the photovoltaic panel increases, the rate of increase of the first tracking voltage is less than that of the second tracking voltage. This allows the photovoltaic energy storage device to dynamically track the output voltage when it fluctuates.

[0043] It is understandable that when the output voltage of the photovoltaic panel remains stable, the first follower voltage and the second follower voltage will overlap. At this time, both the first follower voltage and the second follower voltage are equal to the output voltage of the photovoltaic panel, which is also the input voltage of the photovoltaic energy storage device.

[0044] In this embodiment, by setting a first following voltage and a second following voltage for following the output voltage of the photovoltaic panel, the PV curve of the photovoltaic energy storage device can be determined based on the first following voltage and the second following voltage. This allows the photovoltaic energy storage device to discharge based on the PV curve and the output voltage, enabling the photovoltaic energy storage device to dynamically connect the working voltage range and power range of the photovoltaic panel through the PV curve, thereby reducing the fluctuation of the output voltage and output power of the photovoltaic energy storage device.

[0045] Step S103: Determine the PV curve of the photovoltaic energy storage device discharge based on the first follower voltage, the second follower voltage, and the maximum compensation power of the photovoltaic energy storage device to the photovoltaic inverter.

[0046] After determining the first and second follower voltages corresponding to the input voltage, the PV curve of the photovoltaic energy storage device discharge can be determined based on the first follower voltage, the second follower voltage, and the maximum compensation power of the photovoltaic energy storage device to the photovoltaic inverter.

[0047] The PV curve refers to the relationship between the discharge power and discharge voltage of a photovoltaic energy storage device during discharge. The maximum compensation power of a photovoltaic inverter can be expressed as P. max It should be noted that the maximum compensation power can be determined by the grid-connected power. Grid-connected power refers to the power output from the grid to the AC bus, that is, the power output from the grid to the load, or the power output from the photovoltaic inverter to the grid. It can be understood that when the electricity generated by the photovoltaic panels cannot meet the load demand, the load needs to draw power from the grid, resulting in users paying additional electricity bills. To avoid users paying extra electricity bills, power compensation can be provided by photovoltaic energy storage devices. That is, the DC-DC conversion circuit in the photovoltaic energy storage device outputs power to the photovoltaic inverter, so that the power output from the grid to the load is reduced to zero.

[0048] In some embodiments, determining the PV curve of the photovoltaic energy storage device discharge based on the first follower voltage, the second follower voltage, and the maximum compensation power of the photovoltaic energy storage device to the photovoltaic inverter may include: determining a first sub-PV curve, a second sub-PV curve, and a third sub-PV curve of the PV curve based on the first follower voltage, the second follower voltage, and the maximum compensation power of the photovoltaic energy storage device to the photovoltaic inverter, and determining the PV curve based on the first sub-PV curve, the second sub-PV curve, and the third sub-PV curve.

[0049] Please see Figure 4 , Figure 4 This is a schematic diagram of a PV curve provided in an embodiment of this application. For example... Figure 4 As shown, the horizontal axis represents the discharge voltage, and the vertical axis represents the discharge power. Curve 1 is the first sub-PV curve, curve 2 is the second sub-PV curve, and curve 3 is the third sub-PV curve. On the first sub-PV curve, the discharge power and discharge voltage are positively correlated, and the maximum discharge voltage is the first following voltage V. mid-L The second sub-PV curve is when the discharge voltage is at the first following voltage V. mid-L With the second follower voltage V mid-R The PV curves between the two sub-PV curves show that the discharge power on the second sub-PV curve is equal to the maximum compensation power P. max On the third sub-PV curve, the discharge power is negatively correlated with the discharge voltage, and the maximum discharge voltage is the second follower voltage V. mid-R In this embodiment, the PV curve of the photovoltaic energy storage device is determined based on the first following voltage, the second following voltage, and the maximum compensation power of the photovoltaic energy storage device for the photovoltaic inverter. Since the PV curve incorporates the first and second following voltages, the discharge voltage and discharge power on the PV curve can follow the changes in the output voltage and output power of the photovoltaic panel. Therefore, the PV curve can dynamically connect the operating voltage range and power range of the photovoltaic panel, reducing fluctuations in the output voltage and output power of the photovoltaic energy storage device. Simultaneously, the PV curve also incorporates the maximum compensation power, enabling the target discharge power output by the photovoltaic energy storage device to achieve power compensation for the photovoltaic inverter.

[0050] In some embodiments, the control method for the photovoltaic energy storage device provided in this application may further include: determining a first power output from the grid to the AC bus; and determining a maximum compensation power based on the first power.

[0051] For example, a power detection device can be installed on the AC bus between the power grid and the load to collect the initial power output from the power grid to the AC bus. Alternatively, voltage and current acquisition circuits can be used to collect the voltage and current output from the power grid to the AC bus, and then the initial power can be calculated based on the voltage and current.

[0052] For example, after determining the first power output from the power grid to the AC bus, the first power can be determined as the maximum compensation power.

[0053] In the above embodiments, by determining the first power output from the grid to the AC bus, the compensation power output from the grid to the load can be obtained, and then the compensation power output from the grid can be used as the maximum compensation power of the photovoltaic energy storage device.

[0054] Step S104: Based on the PV curve and output voltage, determine the target discharge power of the photovoltaic energy storage device.

[0055] For example, after determining the PV curve of the photovoltaic energy storage device's discharge, the target discharge power of the photovoltaic energy storage device can be determined based on the PV curve and the output voltage. The target discharge power can be represented as P.

[0056] In this embodiment, the relationship between the output voltage and discharge power on the PV curve can be expressed using the following power calculation formula:

[0057] In the formula, V min V represents the minimum discharge voltage of a photovoltaic energy storage device when it outputs its minimum discharge power. max Vpv represents the maximum discharge voltage of the photovoltaic energy storage device when it outputs the minimum discharge power. Vpv is the input voltage of the photovoltaic energy storage device and also the output voltage of the photovoltaic panel.

[0058] It is understandable that when the photovoltaic energy storage device is in the discharge state, its output voltage Vout will be determined by the photovoltaic inverter due to the MPPT tracking of the photovoltaic inverter. At this time, based on the Vout required by the photovoltaic inverter and the above PV curve, the photovoltaic energy storage device can determine the target output power to be output to the photovoltaic inverter, and then control the output current so that the output power output to the photovoltaic inverter is equal to the target output power P.

[0059] In the above embodiments, the target discharge power of the photovoltaic energy storage device is determined based on the PV curve and output voltage. Subsequently, the photovoltaic energy storage device can be controlled to discharge according to the target discharge power to compensate the photovoltaic inverter. This allows the photovoltaic energy storage device to compensate the photovoltaic inverter for power while simultaneously controlling the discharge of the photovoltaic energy storage device based on the PV curve. This enables the photovoltaic energy storage device to dynamically connect the working voltage range and power range of the photovoltaic panel through the PV curve, reducing the impact of fluctuations in the output voltage and output power of the photovoltaic panel on the photovoltaic inverter.

[0060] Step S105: Control the photovoltaic energy storage device to discharge according to the target discharge power to compensate the photovoltaic inverter for power, wherein the output power of the second end is the sum of the input power of the first end and the discharge power of the photovoltaic energy storage device.

[0061] After determining the target discharge power of the photovoltaic energy storage device based on the PV curve and output voltage, the photovoltaic energy storage device can be controlled to discharge according to the target discharge power to compensate the photovoltaic inverter for power.

[0062] For example, the DC-DC conversion circuit in the photovoltaic energy storage device can be controlled to output a target discharge power. In this case, the output power at the second end of the photovoltaic energy storage device is the sum of the input power at the first end and the discharge power of the photovoltaic energy storage device. Since the input power at the first end of the photovoltaic energy storage device is provided by the photovoltaic panel, the input power received by the photovoltaic inverter is the sum of the discharge power of the photovoltaic energy storage device and the output power of the photovoltaic panel. Thus, when the input power of the photovoltaic panel suddenly drops to an extremely low level, the output power of the photovoltaic energy storage device during discharge can roll off from the input voltage of the photovoltaic panel based on the PV curve, ensuring that the maximum power point tracking (MPPT) on the photovoltaic inverter side can be performed normally. This prevents the output voltage of the photovoltaic energy storage device from continuously increasing or decreasing due to the absence of a maximum power point, which could ultimately lead to a restart of the photovoltaic inverter. In other words, when the power of the photovoltaic panel suddenly disappears, the PV curve of the photovoltaic energy storage device during discharge dynamically changes based on the output voltage of the photovoltaic panel, which to some extent connects the operating voltage range and power range of the photovoltaic panel, minimizing the number of times the photovoltaic inverter restarts when the output voltage or output power of the photovoltaic panel is too low.

[0063] Please see Figure 5 , Figure 5 This is a schematic flowchart illustrating a sub-step for determining a following voltage, as provided in an embodiment of this application. Figure 5 As shown, determining the first follower voltage and the second follower voltage corresponding to the input voltage in step S102 may include the following steps S201 and S202.

[0064] Step S201: Determine the target following voltage based on the input voltage.

[0065] For example, when determining the target following voltage based on the input voltage, the input voltage can be directly determined as the target following voltage. The target following voltage can be expressed as V. mid .

[0066] It should be noted that by determining the input voltage as the target following voltage, the PV curve of the photovoltaic energy storage device's discharge can be generated based on the target following voltage. In this way, the input voltage can be followed through the PV curve, reducing the impact of the photovoltaic panel's output voltage fluctuations on the photovoltaic inverter.

[0067] In this embodiment of the application, in order to ensure that the discharge voltage at the second end of the photovoltaic energy storage device meets the voltage range required for the normal operation of the photovoltaic inverter, the target following voltage needs to be limited when determining the target following voltage based on the input voltage.

[0068] In some embodiments, when determining the target following voltage based on the input voltage, the input voltage can be limited based on the operating voltage range of the photovoltaic inverter, and the limited input voltage can be determined as the target following voltage.

[0069] Step S202: Determine the first following voltage and the second following voltage based on the target following voltage, wherein the first following voltage is less than or equal to the target following voltage, and the second following voltage is greater than or equal to the target following voltage.

[0070] After determining the target following voltage based on the input voltage, a first following voltage and a second following voltage can be determined based on the target following voltage. The first following voltage is less than or equal to the target following voltage, and the second following voltage is greater than or equal to the target following voltage.

[0071] It should be noted that in related technologies, when the output power of the photovoltaic panel is too low, if the discharge power of the photovoltaic energy storage device is not adjusted in time, the input voltage of the photovoltaic inverter (i.e., the output voltage of the photovoltaic energy storage device) is prone to shifting towards the upper voltage limit (either the upper limit of the input voltage of the photovoltaic inverter or the upper limit of the output voltage of the photovoltaic energy storage device) or 0V when the photovoltaic inverter performs maximum power point tracking, causing the photovoltaic inverter to restart. In this embodiment, by setting a first following voltage and a second following voltage, when the output voltage of the photovoltaic panel decreases, the first following voltage slows down the shift of the photovoltaic inverter's input voltage towards 0V, and the second following voltage slows down the shift of the input voltage towards the upper voltage limit. This effectively reduces the number of times the photovoltaic inverter restarts when the output voltage or output power of the photovoltaic panel is too low. Furthermore, after the output power or output voltage of the photovoltaic panel disappears, the first following voltage can quickly reduce the input voltage of the photovoltaic inverter, making it closer to the output voltage of the photovoltaic panel, facilitating rapid connection of the photovoltaic panel, ensuring maximum utilization of photovoltaic panel energy, and reducing the waste of photovoltaic power.

[0072] In some embodiments, determining the first follower voltage and the second follower voltage based on the target follower voltage may include: when the target follower voltage remains stable, controlling the first follower voltage and the second follower voltage to be equal to the target follower voltage; when the target follower voltage decreases, controlling the voltage drop rate of the first follower voltage to be greater than the voltage drop rate of the second follower voltage; and when the target follower voltage increases, controlling the voltage rise rate of the second follower voltage to be greater than the voltage rise rate of the first follower voltage.

[0073] Please see Figure 6 , Figure 6 This is a schematic diagram of a voltage follower provided in an embodiment of this application. For example... Figure 6 As shown, the horizontal axis represents time, and the vertical axis represents voltage. The target follows the voltage V. mid When the voltage remains stable, the first follower voltage V can be... mid-L Second follower voltage V mid-R Set to equal to the target follower voltage V mid At the target following voltage V mid During the descent, the first follower voltage V can be controlled. mid-L The rate of voltage drop is greater than that of the second follower voltage V. mid-R The rate of voltage drop. At the target following voltage V mid During the rise, control the second follower voltage V mid-R The voltage rise rate is greater than the first follower voltage V. mid-L The rate of voltage rise.

[0074] In the above embodiment, by controlling the rate of decrease of the first following voltage to be greater than the rate of decrease of the second following voltage when the target following voltage decreases, and controlling the rate of increase of the second following voltage to be greater than the rate of increase of the first following voltage when the target following voltage increases, the rise and fall rates of the first and second following voltages are different. This allows the PV curve of the photovoltaic energy storage device to rapidly expand left and right with the target following voltage as a reference when the output voltage of the photovoltaic panel decreases or increases, thus achieving the desired result. Figure 4 The PV curve shown demonstrates that the discharge power of the photovoltaic energy storage device can quickly follow the changes in the output voltage of the photovoltaic panel.

[0075] Please see Figure 7 , Figure 7 This is a schematic flowchart illustrating a sub-step for determining a target following voltage, as provided in an embodiment of this application. Figure 7 As shown, determining the target following voltage based on the input voltage in step S201 may include the following steps S301 and S302.

[0076] Step S301: Determine the input voltage as the initial following voltage.

[0077] For example, the input voltage can be determined as the initial follower voltage.

[0078] Step S302: Limit the initial following voltage according to the maximum and minimum operating voltages of the photovoltaic inverter to obtain the target following voltage.

[0079] For example, when limiting the initial following voltage based on the maximum and minimum operating voltages of the photovoltaic inverter, the voltage values ​​in the initial following voltage that are greater than the maximum operating voltage can be set as the maximum operating voltage, and the voltage values ​​in the initial following voltage that are less than the maximum operating voltage can be set as the minimum operating voltage, thus obtaining the limited initial following voltage. This limited initial following voltage is then determined as the target following voltage.

[0080] In this embodiment, to ensure that the photovoltaic inverter has sufficient voltage margin for maximum power point tracking, when limiting the initial following voltage based on the minimum operating voltage of the photovoltaic inverter, a preset voltage value needs to be added to the minimum operating voltage before limiting the initial following voltage. The preset voltage value can be set according to actual conditions, and the specific value is not limited here. For example, the preset voltage value can be 10%, 20%, etc., of the minimum operating voltage. For instance, the initial following voltage can be limited based on 110% of the minimum operating voltage.

[0081] In the above embodiments, by limiting the initial following voltage according to the maximum and minimum operating voltages of the photovoltaic inverter, the target following voltage can be made to conform to the voltage range required for the normal operation of the photovoltaic inverter.

[0082] Please see Figure 8 , Figure 8 This is a schematic flowchart illustrating a sub-step for determining a first sub-PV curve, as provided in an embodiment of this application. Figure 8 As shown, determining the first sub-PV curve of the PV curve may include the following steps S401 to S403.

[0083] Step S401: Determine the minimum discharge voltage corresponding to the minimum discharge power of the photovoltaic energy storage device.

[0084] It should be noted that the discharge power of the photovoltaic energy storage device needs to be sufficient for the photovoltaic inverter to perform MPPT tracking normally. Therefore, the discharge power output of the photovoltaic energy storage device will reach its minimum value whether the discharge voltage is too low or too high. Thus, the photovoltaic energy storage device has a minimum discharge voltage and a maximum discharge voltage corresponding to its minimum discharge power.

[0085] For example, when determining the minimum discharge voltage corresponding to the minimum discharge power of a photovoltaic energy storage device, since the photovoltaic energy storage device has both a minimum discharge voltage and a maximum discharge voltage at the minimum discharge power, the minimum discharge voltage corresponding to the minimum discharge power can be obtained. For instance, when the minimum discharge power of the photovoltaic energy storage device is 0W, the minimum discharge voltage of the photovoltaic energy storage device at 0W can be obtained. Here, the minimum discharge power can be expressed as P. min The minimum discharge voltage can be expressed as V. min .

[0086] Step S402: Determine the power change slope of the first sub-PV curve based on the minimum discharge voltage, minimum discharge power, maximum compensation power, and first follower voltage.

[0087] For example, in determining the minimum discharge power P of the photovoltaic energy storage device min The corresponding minimum discharge voltage V min Then, based on the minimum discharge voltage V min Minimum discharge power P min Maximum compensation power P max and the first follower voltage V mid-L The power change slope of the first sub-PV curve is determined. For example, the power change slope of the first sub-PV curve can be calculated based on the least squares formula or other linear fitting algorithms.

[0088] The power change slope of the first sub-PV curve can include the power change slopes corresponding to multiple sampling points. For example, when determining the minimum discharge voltage V... min Minimum discharge power P min Maximum compensation power P max and the first follower voltage V mid-L Then, the discharge voltage corresponding to multiple sampling points of the photovoltaic energy storage device can be measured. Based on the least squares formula or other linear fitting algorithms, the discharge voltage and minimum discharge voltage V at each sampling point can be determined. min Maximum compensation power P max and the first follower voltage V mid-L The power change slope is calculated to obtain the power change slope corresponding to each sampling point. The specific calculation process for the power change slope is not described in detail here.

[0089] In the above embodiment, by calculating the power change slope based on the minimum discharge voltage, minimum discharge power, maximum compensation power, first follow-up voltage, and discharge voltage at each sampling point, the power change slope corresponding to multiple sampling points can be obtained, and thus the power change slope of the first sub-PV curve can be obtained.

[0090] Step S403: Generate the first sub-PV curve based on the power change slope of the first sub-PV curve.

[0091] For example, after determining the power change slope corresponding to each sampling point, a first sub-PV curve can be generated based on the power change slope corresponding to each sampling point. For instance, the first sub-PV curve can be generated based on the power change slope corresponding to each sampling point, according to the minimum discharge voltage, minimum discharge power, maximum compensation power, and first following voltage. The starting point of the first sub-PV curve can be determined based on the minimum discharge voltage and minimum discharge power, and the ending point can be determined based on the maximum compensation power and the first following voltage.

[0092] It should be noted that on the first sub-PV curve, the discharge power is positively correlated with the discharge voltage, and the slope of the power change decreases as the discharge voltage increases. When the discharge voltage is the minimum discharge voltage V... min When the power change slope is 1, the corresponding discharge power is the minimum discharge power P. min When the discharge voltage is the first following voltage, the slope of the power change is 0, and the corresponding discharge power is equal to the maximum compensation power.

[0093] In the above embodiment, the starting point of the first sub-PV curve is determined based on the minimum discharge voltage and the minimum discharge power, and the ending point of the first sub-PV curve is determined based on the maximum compensation power and the first following voltage. Then, the first sub-PV curve can be generated based on the power change slope corresponding to each sampling point.

[0094] Please see Figure 9 , Figure 9 This is a schematic flowchart illustrating a sub-step for determining a second sub-PV curve, as provided in an embodiment of this application. Figure 9 As shown, determining the second sub-PV curve of the PV curve may include the following steps S501 and S502.

[0095] Step S501: Determine the power change slope of the second sub-PV curve based on the maximum compensation power, the first follower voltage, and the second follower voltage.

[0096] It should be noted that since the discharge power is the maximum compensation power when the discharge voltage is between the first follower voltage and the second follower voltage, it can be determined that the power change slope of the second sub-PV curve is 0.

[0097] Step S502: Generate the second sub-PV curve based on the power change slope of the second sub-PV curve.

[0098] For example, the second sub-PV curve can be generated based on the power change slope of the second sub-PV curve, according to the maximum compensation power, the first follower voltage, and the second follower voltage.

[0099] It should be noted that the power change slope of the second sub-PV curve is 0, and the discharge voltage range is between the first and second follower voltages. Within the entire discharge voltage range, the corresponding discharge power is the maximum compensation power. That is, the discharge power corresponding to each discharge voltage on the second sub-PV curve is equal to the maximum compensation power.

[0100] Please see Figure 10 , Figure 10 This is a schematic flowchart illustrating a sub-step for determining a third sub-PV curve, as provided in an embodiment of this application. Figure 10 As shown, determining the third sub-PV curve of the PV curve may include the following steps S601 to S603.

[0101] Step S601: Determine the maximum discharge voltage corresponding to the minimum discharge power of the photovoltaic energy storage device.

[0102] For example, when determining the maximum discharge voltage corresponding to the minimum discharge power of a photovoltaic energy storage device, since the photovoltaic energy storage device has both a minimum discharge voltage and a maximum discharge voltage at the minimum discharge power, the maximum discharge voltage corresponding to the minimum discharge power can be obtained. For instance, when the minimum discharge power of the photovoltaic energy storage device is 0W, the maximum discharge voltage of the photovoltaic energy storage device at 0W can be obtained. Here, the minimum discharge power can be expressed as P. min The maximum discharge voltage can be expressed as V. max .

[0103] Step S602: Determine the power change slope of the third sub-PV curve based on the maximum compensation power, the second follower voltage, the maximum discharge voltage, and the minimum discharge power.

[0104] For example, in determining the minimum discharge power P of the photovoltaic energy storage device min The corresponding maximum discharge voltage V max Then, based on the maximum discharge voltage V max Minimum discharge power P min Maximum compensation power P max And the voltage V that follows mid-R The slope of the power change in the third sub-PV curve is determined. For example, the slope of the power change can be calculated based on the least squares formula or other linear fitting algorithms to obtain the slope of the power change in the third sub-PV curve.

[0105] The power change slope of the third sub-PV curve can include the power change slopes corresponding to multiple sampling points. For example, when determining the maximum discharge voltage V... max Minimum discharge power P min Maximum compensation power P max and the second follower voltage V mid-R Then, the discharge voltage corresponding to multiple sampling points of the photovoltaic energy storage device can be measured. Based on the least squares formula or other linear fitting algorithms, the discharge voltage and minimum discharge voltage V at each sampling point can be determined. min Maximum compensation power P max and the second follower voltage V mid-R The power change slope is calculated to obtain the power change slope corresponding to each sampling point. The specific calculation process for the power change slope is not described in detail here.

[0106] In the above embodiment, by calculating the power change slope based on the maximum discharge voltage, minimum discharge power, maximum compensation power, second follower voltage, and discharge voltage at each sampling point, the power change slope corresponding to multiple sampling points can be obtained, and thus the power change slope of the second sub-PV curve can be obtained.

[0107] Step S603: Generate the third sub-PV curve based on the power change slope of the third sub-PV curve.

[0108] For example, after determining the power change slope corresponding to each sampling point, a third sub-PV curve can be generated based on the power change slope corresponding to each sampling point. For instance, the third sub-PV curve can be generated based on the power change slope corresponding to each sampling point, according to the maximum discharge voltage, minimum discharge power, maximum compensation power, and second follower voltage. The starting point of the third sub-PV curve can be determined based on the maximum compensation power and the first follower voltage, and the ending point can be determined based on the maximum discharge voltage and the minimum discharge power.

[0109] It should be noted that on the third sub-PV curve, the discharge power is negatively correlated with the discharge voltage, and the slope of the power change increases with the increase of the discharge voltage. When the discharge voltage is the second follower voltage, the slope of the power change is 0, and the corresponding discharge power is equal to the maximum compensation power. When the discharge voltage is the maximum discharge voltage V... min When the power change slope is 1, the corresponding discharge power is the minimum discharge power P. min .

[0110] In the above embodiment, the starting point of the third sub-PV curve is determined based on the maximum compensation power and the first following voltage, and the ending point of the third sub-PV curve is determined based on the maximum discharge voltage and the minimum discharge power. Then, the third sub-PV curve can be generated based on the power change slope corresponding to each sampling point.

[0111] The embodiments of this application also provide a computer-readable storage medium storing a computer program, which includes program instructions. The controller executes the program instructions to implement any of the photovoltaic energy storage device control methods provided in the embodiments of this application.

[0112] For example, when the program is loaded by the controller, it can perform the following steps: The process involves: acquiring the input voltage at the first terminal of the photovoltaic energy storage device and the output voltage at the second terminal of the photovoltaic energy storage device; determining the first and second follower voltages corresponding to the input voltage; determining the PV curve of the photovoltaic energy storage device's discharge based on the first and second follower voltages and the maximum compensation power of the photovoltaic energy storage device for the photovoltaic inverter; determining the target discharge power of the photovoltaic energy storage device based on the PV curve and the output voltage; and controlling the discharge of the photovoltaic energy storage device according to the target discharge power to compensate the photovoltaic inverter for power loss. The output power at the second terminal is the sum of the input power at the first terminal and the discharge power of the photovoltaic energy storage device.

[0113] The computer-readable storage medium can be an internal storage unit of the photovoltaic energy storage device described in the foregoing embodiments, such as a hard drive or memory of the photovoltaic energy storage device. Alternatively, the computer-readable storage medium can be an external storage device of the photovoltaic energy storage device, such as a plug-in hard drive, smart media card (SMC), secure digital card (SD card), flash card, etc., equipped on the photovoltaic energy storage device.

[0114] Furthermore, a computer-readable storage medium may primarily include a program storage area and a data storage area, wherein the program storage area may store the operating system, programs required for at least one function, etc.; and the data storage area may store data created according to each program, etc.

[0115] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A control method for a photovoltaic energy storage device, characterized in that, The first end of the photovoltaic energy storage device is connected to the photovoltaic panel, and the second end of the photovoltaic energy storage device is connected to the photovoltaic inverter. The method includes: Obtain the input voltage at the first terminal of the photovoltaic energy storage device and the output voltage at the second terminal of the photovoltaic energy storage device; Determine the first follower voltage and the second follower voltage corresponding to the input voltage; Based on the first following voltage, the second following voltage, and the maximum compensation power of the photovoltaic energy storage device to the photovoltaic inverter, the PV curve of the photovoltaic energy storage device discharge is determined. Based on the PV curve and the output voltage, the target discharge power of the photovoltaic energy storage device is determined; The photovoltaic energy storage device is controlled to discharge according to the target discharge power to compensate the photovoltaic inverter for power, wherein the output power of the second terminal is the sum of the input power of the first terminal and the discharge power of the photovoltaic energy storage device; The step of determining the PV curve of the photovoltaic energy storage device's discharge based on the first following voltage, the second following voltage, and the maximum compensation power of the photovoltaic energy storage device to the photovoltaic inverter includes: Determine the first sub-PV curve of the PV curve; the discharge power on the first sub-PV curve is positively correlated with the discharge voltage and the maximum discharge voltage is the first following voltage; A second sub-PV curve is determined from the PV curve; the discharge voltage range of the second sub-PV curve is between the first following voltage and the second following voltage, and the discharge power on the second sub-PV curve is equal to the maximum compensation power; A third sub-PV curve is determined on the PV curve, wherein the discharge power on the third sub-PV curve is negatively correlated with the discharge voltage and the maximum discharge voltage is the second follower voltage; The PV curve is determined based on the first sub-PV curve, the second sub-PV curve, and the third sub-PV curve.

2. The control method for the photovoltaic energy storage device according to claim 1, characterized in that, Determining the first follower voltage and the second follower voltage corresponding to the input voltage includes: Determine the target following voltage based on the input voltage; Based on the target following voltage, a first following voltage and a second following voltage are determined, wherein the first following voltage is less than or equal to the target following voltage, and the second following voltage is greater than or equal to the target following voltage.

3. The control method for the photovoltaic energy storage device according to claim 2, characterized in that, Determining the first following voltage and the second following voltage based on the target following voltage includes: When the target following voltage remains stable, the first following voltage and the second following voltage are controlled to be equal to the target following voltage; When the target following voltage decreases, the voltage decrease rate of the first following voltage is controlled to be greater than the voltage decrease rate of the second following voltage; When the target following voltage rises, the voltage rise rate of the second following voltage is controlled to be greater than the voltage rise rate of the first following voltage.

4. The control method for the photovoltaic energy storage device according to claim 2, characterized in that, Determining the target following voltage based on the input voltage includes: The input voltage is determined as the initial follower voltage; The initial following voltage is limited based on the maximum and minimum operating voltages of the photovoltaic inverter to obtain the target following voltage.

5. The control method for the photovoltaic energy storage device according to claim 1, characterized in that, Determining the first sub-PV curve of the PV curve includes: Determine the minimum discharge voltage corresponding to the minimum discharge power of the photovoltaic energy storage device; The power change slope of the first sub-PV curve is determined based on the minimum discharge voltage, the minimum discharge power, the maximum compensation power, and the first follower voltage. The first sub-PV curve is generated based on the power change slope of the first sub-PV curve.

6. The control method for the photovoltaic energy storage device according to claim 1, characterized in that, The determination of the third sub-PV curve of the PV curve includes: Determine the maximum discharge voltage corresponding to the minimum discharge power of the photovoltaic energy storage device; The power change slope of the third sub-PV curve is determined based on the maximum compensation power, the second follower voltage, the maximum discharge voltage, and the minimum discharge power. The third sub-PV curve is generated based on the power change slope of the third sub-PV curve.

7. The control method for the photovoltaic energy storage device according to any one of claims 1-6, characterized in that, The first terminal of the photovoltaic inverter is connected to the power grid via an AC bus, and the second terminal of the photovoltaic inverter is connected to the second terminal of the photovoltaic energy storage device. The photovoltaic inverter is used to convert the electrical energy output from the photovoltaic energy storage device into AC / DC power to supply power to the load connected to the AC bus; the method further includes: Determine the first power output from the power grid to the AC bus; The maximum compensation power is determined based on the first power.

8. A photovoltaic energy storage device, characterized in that, The photovoltaic energy storage device includes a memory and a controller; The memory is used to store computer programs; The controller is configured to execute the computer program and, in executing the computer program, implement the control method for the photovoltaic energy storage device as described in any one of claims 1 to 7.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by the controller, causes the controller to implement the control method for the photovoltaic energy storage device as described in any one of claims 1 to 7.

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