Photovoltaic grid-connected control method, control terminal and storage medium

Abstract

The application provides a photovoltaic grid-connected control method, a control terminal and a storage medium, and the method is applied to a photovoltaic system; the photovoltaic system comprises a photovoltaic assembly, an energy storage module, a DC / DC module and an inverter module; the photovoltaic assembly is connected with a direct current end of the inverter module; the energy storage module is connected with the direct current end of the inverter module through the DC / DC module; an alternating current end of the inverter module is connected with a power grid; the method comprises the following steps: obtaining working states of the photovoltaic assembly and the DC / DC module; if the photovoltaic assembly and the DC / DC module are both normally working, the inverter module is controlled to work in a constant power mode, the DC / DC module is controlled to work in an MPPT mode, and the photovoltaic assembly is subjected to maximum power point tracking. The photovoltaic assembly is subjected to maximum power point tracking by the DC / DC module, the inverter module is operated in a constant power mode, the grid-connected power of the inverter module is relatively stable, and the calculation of the grid-connected power of the photovoltaic system is simpler.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and in particular to a photovoltaic grid-connected control method, control terminal, and storage medium. Background Technology

[0002] With the emergence of the concept of sustainable development, solar photovoltaic (PV) power generation, as a clean and renewable energy source, has been widely adopted. Due to the volatility and randomness of PV power generation, energy storage modules are typically incorporated into PV systems. (Reference) Figure 1 A photovoltaic system includes: photovoltaic modules, energy storage modules, DC-DC modules, and inverter modules.

[0003] In existing technologies, the inverter module is typically set to MPPT mode to perform maximum power point tracking of the photovoltaic modules, and the DC-DC module is set to constant power mode. Because photovoltaic power generation is random and fluctuating, the grid-connected power of the inverter changes constantly, making the calculation of the grid-connected power of the photovoltaic system inconvenient. Summary of the Invention

[0004] This invention provides a photovoltaic grid-connected control method, control terminal, and storage medium to solve the problems in the prior art where the grid-connected power of the inverter changes continuously, the grid-connected power is not stable enough, and it is inconvenient to calculate.

[0005] In a first aspect, embodiments of the present invention provide a photovoltaic grid-connected control method applied to a photovoltaic system; the photovoltaic system includes: photovoltaic modules, an energy storage module, a DC-DC converter module, and an inverter module; the photovoltaic modules are connected to the DC terminals of the inverter module; the energy storage module is connected to the DC terminals of the inverter module through the DC-DC converter module; the AC terminals of the inverter module are connected to the power grid; the method includes:

[0006] Obtain the operating status of photovoltaic modules and DC-DC modules;

[0007] If both the photovoltaic module and the DC-DC module are working normally, the inverter module is controlled to operate in constant power mode, and the DC-DC module is controlled to operate in MPPT mode to perform maximum power point tracking on the photovoltaic module.

[0008] In a second aspect, embodiments of the present invention provide a control terminal, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of the photovoltaic grid-connected control method provided in the first aspect or any possible implementation of the first aspect.

[0009] Thirdly, embodiments of the present invention provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the photovoltaic grid-connected control method provided in the first aspect or any possible implementation thereof.

[0010] This invention provides a photovoltaic (PV) grid-connected control method, control terminal, and storage medium. The method is applied to a PV system. The PV system includes: PV modules, an energy storage module, a DC-DC converter module, and an inverter module. The PV modules are connected to the DC terminals of the inverter module. The energy storage module is connected to the DC terminals of the inverter module via the DC-DC converter module. The AC terminals of the inverter module are connected to the power grid. The method includes: acquiring the operating status of the PV modules and the DC-DC converter module; if both the PV modules and the DC-DC converter module are operating normally, controlling the inverter module to operate in constant power mode and controlling the DC-DC converter module to operate in MPPT mode to perform maximum power point tracking (MPPT) on the PV modules. In this invention, the DC-DC converter is controlled to perform MPPT on the PV modules, the inverter module operates at constant power, and the DC-DC converter module smooths out fluctuations in the output power of the PV modules, resulting in relatively stable grid-connected power of the inverter module and simpler interaction control between the PV system and the power grid. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of the photovoltaic system.

[0013] Figure 2 This is a flowchart illustrating the implementation of a photovoltaic grid-connected control method provided in an embodiment of the present invention;

[0014] Figure 3 This is a schematic diagram of the working mode of the photovoltaic system provided in the embodiment of the present invention;

[0015] Figure 4 This is a schematic diagram of the structure of the photovoltaic grid-connected control device provided in an embodiment of the present invention;

[0016] Figure 5 This is a schematic diagram of the control terminal provided in an embodiment of the present invention. Detailed Implementation

[0017] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0018] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments will be described below in conjunction with the accompanying drawings.

[0019] See Figure 1 The invention illustrates a photovoltaic system comprising: a photovoltaic module 11, an energy storage module 12, a DC-DC converter module 13, and an inverter module 14; the photovoltaic module 11 is connected to the DC terminal of the inverter module 14; the energy storage module 12 is connected to the DC terminal of the inverter module 14 via the DC-DC converter module 13; the AC terminal of the inverter module 14 is connected to the power grid; based on the above photovoltaic system, this embodiment of the invention provides a photovoltaic grid-connected control method, applied to the above photovoltaic system; Reference Figure 2 The above methods include:

[0020] S101: Obtain the operating status of photovoltaic module 11 and DC-DC module 13;

[0021] S102: If both the photovoltaic module 11 and the DC-DC module 13 are working normally, the inverter module 14 is controlled to work in constant power mode, and the DC-DC module 13 is controlled to work in MPPT mode to perform maximum power point tracking on the photovoltaic module 11.

[0022] In this embodiment of the invention, the photovoltaic module 11 is subjected to maximum power point tracking by the DC-DC module 13, and the inverter module 14 operates at constant power. The DC-DC module 13 smooths out the fluctuations in the output power of the photovoltaic module 11, so that the grid-connected power of the inverter module 14 is relatively stable and the power is constant in a short period of time, making the grid-connected power calculation simpler and more accurate.

[0023] Meanwhile, maximum power point tracking is performed by the DC-DC module 13, and there is no interaction between the DC-DC module 13 and the power grid, making control simpler.

[0024] It should be noted that the above method is effective regardless of whether inverter module 14 is connected to the grid. When inverter module 14 is connected to the grid, inverter module 14 operates at constant power, and DC-DC module 13 operates in MPPT mode.

[0025] When inverter module 14 is not connected to the grid, turning off inverter module 14 can be understood as inverter module 14 having 0 power and still operating in constant power mode. DC-DC module 13 also operates in MPPT mode.

[0026] In one possible implementation, the above method may further include:

[0027] S103: If inverter module 14 is connected to the grid, then obtain the power of DC-DC module 13;

[0028] S104: If the power of the DC-DC module 13 is not within the preset range, adjust the output power of the inverter module 14 so that the power of the DC-DC module 13 is within the preset range.

[0029] S105: If the power of the DC-DC module 13 is within the preset range, control the inverter module 14 to output constant power according to the current power.

[0030] The preset range is from the first threshold to the second threshold; the first threshold is less than the second threshold.

[0031] During peak electricity consumption periods, the power grid is usually insufficient and electricity prices are high. For economic reasons, when electricity prices are high during peak consumption periods, the photovoltaic system should output power to the grid at its maximum capacity (inverter module 14 supplies energy to the grid) to obtain the greatest economic benefits.

[0032] When grid electricity prices are typically high, the grid-connected output power of inverter module 14 is increased (inverter module 14 supplies energy to the grid, i.e., the grid-connected power is positive). If the power of photovoltaic module 11 is insufficient (relative to grid-connected power) or if photovoltaic module 11 malfunctions, DC-DC module 13 supplements the power supply (see reference). Figure 3 In modes one and five of the above, the grid electricity price is usually high. Therefore, a preset range less than the maximum discharge power is set to control the power of the DC-DC module 13 to discharge within the preset range, ensuring that the photovoltaic system is connected to the grid at maximum power to obtain the greatest economic benefits. If the photovoltaic module 11 has sufficient power and the grid-connected power reaches the upper limit of the allowable grid-connected power (i.e., the photovoltaic module power is greater than the maximum grid-connected power), the excess power of the photovoltaic module 11 can be used by the DC-DC module 13 to charge the energy storage module 12 (see reference). Figure 3 (Mode 2 in the text).

[0033] When grid electricity prices are typically low, reducing the grid-connected power of inverter module 14 allows the DCDC module 13 to charge energy storage module 12. Since grid electricity prices are usually low at this time, the DCDC module 13 is controlled within a preset range to charge energy storage module 12 at maximum power (see reference). Figure 3 (Mode 2). If the power of photovoltaic module 11 is insufficient (relative to the charging power of the energy storage module) or if photovoltaic module 11 malfunctions, inverter module 14 supplements the energy supply (the inverter module absorbs energy from the grid, i.e., the grid-connected power is negative) (refer to...). Figure 3In modes three and four, if the photovoltaic module 11 has sufficient power and the charging power of the energy storage module reaches the upper limit of the allowable limit (i.e., the photovoltaic module power is greater than the maximum charging power), the inverter module 14 is connected to the grid to absorb the excess power of the photovoltaic module 11 (the inverter module outputs energy to the grid, i.e., the grid-connected power is positive) (refer to...). Figure 3 (Mode 2 in the text).

[0034] At the same time, a certain amount of flexibility is reserved for the DC-DC module 13 to avoid frequent adjustments to the output power of the inverter module 14, thereby improving the economy and stability of the system.

[0035] In one possible implementation, S104 may include:

[0036] S1041: If the power of DC-DC module 13 is greater than the second threshold, then reduce the output power of inverter module 14;

[0037] S1042: If the power of DC-DC module 13 is less than the first threshold, then increase the output power of inverter module 14;

[0038] S1043: Repeat steps S041 to S1042 until the power of DC-DC module 13 is within the preset range;

[0039] Specifically, when the DC-DC module 13 is in a discharging state, the power of the DC-DC module 13 is positive; when the DC-DC module 13 is in a charging state, the power of the DC-DC module 13 is negative.

[0040] For example, the power of the DC-DC module 13 during discharge is defined as positive.

[0041] 1. When DC-DC module 13 discharges, both the first threshold and the second threshold are positive;

[0042] If the discharge power of DC-DC module 13 is greater than the second threshold, it indicates that the discharge power of DC-DC module 13 is about to reach its maximum. Since it still cannot reach the set power of inverter module 14, the DC bus may be pulled down. Therefore, in this embodiment of the invention, the output power of inverter module 14 (that is, the set power when inverter module 14 is outputting at constant power) is appropriately reduced to bring the discharge power of DC-DC module 13 back to the preset range and prevent the DC bus from being pulled down.

[0043] If the discharge power of DC-DC module 13 is less than the first threshold, it indicates that the power of DC-DC module 13 is too small. The output power of inverter module 14 can be appropriately increased to improve the discharge power of DC-DC module 13 and bring the discharge power of DC-DC module 13 back to the preset range, so that the photovoltaic system can be connected to the grid at high power to obtain the maximum benefit.

[0044] If the discharge power of the DC-DC module 13 is within the preset range, the current operating state can be maintained, the photovoltaic system can work stably, and the stability and reliability of the photovoltaic system can be effectively improved.

[0045] 2. When the DC-DC module 13 is charging, both the first threshold and the second threshold are negative;

[0046] If the charging power of DC-DC module 13 is less than the first threshold, it means that the charging power of DC-DC module 13 is about to reach its maximum, and there is still residual photovoltaic energy, which will cause curtailment and reduce the efficiency of the photovoltaic system. Therefore, in this embodiment of the invention, the output power of inverter module 14 is appropriately increased to consume the excess photovoltaic energy and bring the discharge power of DC-DC module 13 back to the preset range to avoid curtailment.

[0047] If the discharge power of DC-DC module 13 is greater than the second threshold, it means that the power of DC-DC module 13 is too low. At this time, the output power of inverter module 14 can be appropriately reduced to increase the charging power of DC-DC module 13 and bring the discharge power of DC-DC module 13 back to the preset range.

[0048] Similarly, if the discharge power of the DC-DC module 13 is within the preset range, the current operating state can be maintained, the photovoltaic system can work stably, and the stability and efficiency of the photovoltaic system can be effectively improved.

[0049] In this embodiment of the invention, the output power of the inverter module 14 is adaptively adjusted to limit the power of the DC-DC module 13 within a preset range to meet economic needs and improve system stability.

[0050] In one possible implementation, S1041 may include:

[0051] If the power of DC-DC module 13 is greater than the second threshold, the output power of inverter module 14 will be reduced by a preset step size.

[0052] S1042 may include:

[0053] If the power of DC-DC module 13 is less than the first threshold and the output power of inverter module 14 is less than the preset maximum output power, then the output power of inverter module 14 will be increased by a preset step size.

[0054] In this embodiment of the invention, the power of the inverter module 14 is adjusted slowly and cyclically according to a preset step size to avoid large-scale adjustments affecting the stability of the photovoltaic system. The preset step size can be set according to actual application requirements and is not specifically limited.

[0055] Furthermore, in S1041 and S1042, the output power of the inverter module 14 can be adjusted according to a preset ratio. For example, if the power of the DC-DC module 13 is greater than the second threshold, the output power of the inverter module 14 is reduced by a preset ratio; the specific adjustment method is not limited. In one possible implementation, S104 may further include:

[0056] S1044: If the power of the DC-DC module 13 is less than the first threshold and the output power of the inverter module 14 is not less than the preset maximum output power, then control the output power of the inverter module 14 to remain unchanged.

[0057] If the output power of inverter module 14 has reached its maximum during the control process, the output power of inverter module 14 cannot be adjusted further.

[0058] In one possible implementation, the preset maximum output power can be the power demand of the power grid minus a first deviation value.

[0059] In this embodiment of the invention, a certain threshold is retained to prevent inaccurate data measurement from causing the output power of the inverter module 14 to exceed the power demand of the grid, thus affecting the operation of the grid and improving the reliability of the photovoltaic system.

[0060] In one possible implementation, prior to S104, the method may further include:

[0061] S106: Obtain the maximum power of DC-DC module 13;

[0062] S107: Subtract the second deviation value from the maximum power to obtain the second threshold; subtract the third deviation value from the maximum power to obtain the first threshold;

[0063] When the DC-DC module 13 is in a discharging state, the second and third deviation values ​​are positive; when the DC-DC module 13 is in a charging state, the second and third deviation values ​​are negative.

[0064] The power of the DCDC module 13 is positive when charging and negative when discharging. In this embodiment of the invention, two different preset ranges are set during charging and discharging. When the DCDC module 13 is charging, the maximum power is positive, the second deviation and the third deviation are both positive, and the third deviation is greater than the second deviation, so that the preset range is a positive range less than the maximum power. When discharging, the maximum power is negative, the second deviation and the third deviation are both negative, and the absolute value of the third deviation is less than the absolute value of the second deviation, so that the preset range is a negative range greater than the maximum power.

[0065] For example, when the DC-DC module 13 is charging, the second deviation is 5kW and the third deviation is 10kW. The absolute value of the maximum charging and discharging power of the DC-DC module 13 is Pmax. The preset range is Pmax-10kW (third deviation) to Pmax-5kW (second deviation).

[0066] When the DCDC module 13 is charging, the second deviation is -10kW and the third deviation is -5kW. The maximum charging and discharging power of the DCDC module 13 is Pmax, so the preset range is -Pmax-(-5kW)~-Pmax-(-10kW).

[0067] It should be noted that the second and third deviation values ​​corresponding to the charging and discharging of the DC-DC module 13 are all preset values ​​that can be directly called.

[0068] Specifically, the first deviation value, the second deviation value, and the third deviation value can all be set according to actual application requirements, and there are no specific limitations.

[0069] In one possible implementation, the above method may further include:

[0070] S108: When an abnormality is detected in the DC-DC module 13, the inverter module 14 is controlled to operate in MPPT mode to perform maximum power point tracking on the photovoltaic module 11.

[0071] When the DC-DC module 13 malfunctions, in order to ensure stable system operation and maximize the power output of the photovoltaic module 11, the inverter module 14 can be controlled to operate in MPPT mode to achieve maximum power output of the photovoltaic module 11, avoid curtailment of solar power, and improve the efficiency of the photovoltaic system.

[0072] Specifically, in the embodiments of the present invention, reference is made to... Figure 3 Photovoltaic systems can operate in the following modes;

[0073] Mode 1: When the inverter module 14 is connected to the grid and outputs power, the energy storage module 12 supplements the power of the photovoltaic module 11 by discharging through the DC-DC module 13; the inverter module 14 operates in constant power mode, and the DC-DC module 13 operates in MPPT mode.

[0074] Mode 2: When the inverter module 14 is connected to the grid and the photovoltaic module 11 has sufficient power, it charges the energy storage module 12 through the DC-DC module 13; the inverter module 14 operates in constant power mode and the DC-DC module 13 operates in MPPT mode.

[0075] Mode 3: When the energy storage module 12 needs to be charged and the power of the photovoltaic module 11 is insufficient to meet the charging requirements of the energy storage module 12, the grid supplements the power through the inverter module 14; the inverter module 14 operates in constant power mode and the DC-DC module 13 operates in MPPT mode.

[0076] Mode 4: When the output power of photovoltaic module 11 is 0 or photovoltaic module 11 is abnormal, and energy storage module 12 needs to be charged, the grid charges energy storage module 12 through inverter module 14 and DC-DC module 13 to smooth out peaks and fill valleys.

[0077] Mode 5: When the output power of photovoltaic module 11 is 0 or photovoltaic module 11 is abnormal, and grid connection is required, energy storage module 12 outputs power to the grid through DC-DC module 13 and inverter module 14 to smooth peak and fill valley.

[0078] Mode 6: When the power of DC-DC module 13 is 0, photovoltaic module 11 is connected to the grid and outputs through inverter module 14; inverter module 14 operates in MPPT mode to avoid curtailment of solar power.

[0079] Mode 7: When inverter module 14 fails or is not connected to the grid due to grid limitations, photovoltaic module 11 charges energy storage module 12 through DC-DC module 13. DC-DC module 13 operates in MPPT mode to avoid curtailment of solar power.

[0080] Furthermore, when the photovoltaic system is turned on:

[0081] If the output voltage of the photovoltaic module 11 does not reach the startup voltage, and the DC-DC module 13 is in standby mode, the DC-DC module 13 is started and operates in constant power mode, and the power of the DC-DC module 13 is limited. After the DC-DC module 13 starts, the inverter module 14 is started and operates in MPPT mode.

[0082] If the output voltage of the photovoltaic module 11 reaches the start-up voltage, it controls the DC-DC module 13 to start up and operate in MPPT mode; after the DC-DC module 13 starts up, it controls the inverter module 14 to start up and operate in MPPT mode.

[0083] When the photovoltaic system is turned off:

[0084] The inverter module 14 is shut down; after the inverter module 14 is shut down, the DC-DC module 13 is shut down.

[0085] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0086] The following are device embodiments of the present invention. For details not described in detail, please refer to the corresponding method embodiments described above.

[0087] Figure 4 This diagram illustrates the structure of a photovoltaic grid-connected control device provided in an embodiment of the present invention, which is applied to... Figure 1 The photovoltaic system shown includes: a photovoltaic module 11, an energy storage module 12, a DC-DC converter module 13, and an inverter module 14; the photovoltaic module 11 is connected to the DC terminal of the inverter module 14; the energy storage module 12 is connected to the AC terminal of the inverter module 14 through the DC-DC converter module 13; the AC terminal of the inverter module 14 is connected to the power grid. For ease of explanation, only the parts relevant to the embodiments of the present invention are shown, and are detailed below:

[0088] like Figure 4 As shown, the photovoltaic grid-connected control device includes:

[0089] The first parameter acquisition module 21 is used to acquire the working status of the photovoltaic module 11 and the DC-DC module 13;

[0090] The MPPT control module 22 is used to control the inverter module 14 to operate in constant power mode and the DC-DC module 13 to operate in MPPT mode if both the photovoltaic module 11 and the DC-DC module 13 are working normally, so as to perform maximum power point tracking on the photovoltaic module 11.

[0091] In one possible implementation, the above-described apparatus may further include:

[0092] The second parameter acquisition module is used to acquire the power of the DC-DC module 13 if the inverter module 14 is connected to the grid.

[0093] The power adjustment module is used to adjust the output power of the inverter module 14 so that the power of the DC-DC module 13 is within the preset range if the power of the DC-DC module 13 is not within the preset range.

[0094] The first power holding module is used to control the inverter module 14 to output constant power according to the current power if the power of the DC-DC module 13 is within a preset range.

[0095] The preset range is from the first threshold to the second threshold; the first threshold is less than the second threshold.

[0096] In one possible implementation, the power adjustment module may include:

[0097] The first adjustment unit is used to reduce the output power of the inverter module 14 if the power of the DC-DC module 13 is greater than the second threshold.

[0098] The second adjustment unit is used to increase the output power of the inverter module 14 if the power of the DC-DC module 13 is less than the first threshold.

[0099] The loop unit is used to repeatedly execute the steps of decreasing the output power of the inverter module 14 if the power of the DC-DC module 13 is greater than the second threshold, and increasing the output power of the inverter module 14 if the power of the DC-DC module 13 is less than the first threshold, until the power of the DC-DC module 13 is within a preset range.

[0100] Specifically, when the DC-DC module 13 is in a discharging state, the power of the DC-DC module 13 is positive; when the DC-DC module 13 is in a charging state, the power of the DC-DC module 13 is negative.

[0101] In one possible implementation, the first adjustment unit may be specifically used to: if the power of the DC-DC module 13 is greater than the second threshold, reduce the output power of the inverter module 14 by a preset step size;

[0102] The second adjustment unit can be specifically used to: if the power of the DC-DC module 13 is less than the first threshold and the output power of the inverter module 14 is less than the preset maximum output power, then increase the output power of the inverter module 14 by a preset step size.

[0103] In one possible implementation, the power adjustment module may further include:

[0104] The second power holding module is used to control the output power of the inverter module 14 to remain unchanged if the power of the DC-DC module 13 is less than the first threshold and the output power of the inverter module 14 is not less than the preset maximum output power.

[0105] In one possible implementation, the preset maximum output power can be the power demand of the power grid minus a first deviation value.

[0106] In one possible implementation, the above-described apparatus may further include:

[0107] The third parameter acquisition module is used to obtain the maximum power of the DC-DC module 13;

[0108] The threshold determination module is used to subtract the second deviation value from the maximum power to obtain the second threshold; and to subtract the third deviation value from the maximum power to obtain the first threshold.

[0109] When the DC-DC module 13 is in a discharging state, the second and third deviation values ​​are positive; when the DC-DC module 13 is in a charging state, the second and third deviation values ​​are negative.

[0110] In one possible implementation, the above-described apparatus may further include:

[0111] The fault handling module is used to control the inverter module 14 to operate in MPPT mode and perform maximum power point tracking on the photovoltaic module 11 when an abnormality is detected in the DC-DC module 13.

[0112] Figure 5 This is a schematic diagram of the control terminal 3 provided in an embodiment of the present invention. Figure 5 As shown, the control terminal 3 in this embodiment includes a processor 30 and a memory 31. The memory 31 stores a computer program 32, and the processor 30 calls and runs the computer program 32 stored in the memory 31 to execute the steps in the various photovoltaic grid-connected control method embodiments described above, for example... Figure 2 The steps S101 to S102 are shown. Alternatively, the processor 30 is used to call and run the computer program 32 stored in the memory 31 to implement the functions of each module / unit in the above-described device embodiments, for example... Figure 4 The functions of modules 21 and 22 shown.

[0113] For example, computer program 32 can be divided into one or more modules / units, one or more of which are stored in memory 31 and executed by processor 30 to complete the present invention. One or more modules / units can be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of computer program 32 in control terminal 3. For example, computer program 32 can be divided into... Figure 4 Modules / units 21 to 22 are shown.

[0114] The control terminal 3 can be a desktop computer, laptop, handheld computer, or cloud server, etc. The control terminal 3 may include, but is not limited to, a processor 30 and a memory 31. Those skilled in the art will understand that... Figure 5 This is merely an example of control terminal 3 and does not constitute a limitation on control terminal 3. It may include more or fewer components than shown, or combine certain components, or different components. For example, the terminal may also include input / output devices, network access devices, buses, etc.

[0115] The processor 30 may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0116] The memory 31 can be an internal storage unit of the control terminal 3, such as a hard disk or RAM of the control terminal 3. The memory 31 can also be an external storage device of the control terminal 3, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the control terminal 3. Furthermore, the memory 31 can include both internal and external storage units of the control terminal 3. The memory 31 is used to store computer programs and other programs and data required by the terminal. The memory 31 can also be used to temporarily store data that has been output or will be output.

[0117] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0118] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0119] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0120] In the embodiments provided by this invention, it should be understood that the disclosed devices / terminals and methods can be implemented in other ways. For example, the device / terminal embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0121] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0122] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0123] If an integrated module / unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc.

[0124] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A photovoltaic grid-connected control method, characterized in that, The method is applied to a photovoltaic system; the photovoltaic system includes: photovoltaic modules, an energy storage module, a DC-DC converter module, and an inverter module; the photovoltaic modules are connected to the DC terminal of the inverter module; the energy storage module is connected to the DC terminal of the inverter module through the DC-DC converter module; the AC terminal of the inverter module is connected to the power grid; the method includes: Obtain the operating status of the photovoltaic module and the DC-DC module; If both the photovoltaic module and the DC-DC module are working normally, the inverter module is controlled to operate in constant power mode, and the DC-DC module is controlled to operate in MPPT mode to perform maximum power point tracking on the photovoltaic module. The method further includes: If the inverter module is connected to the grid, the power of the DC-DC module is obtained; If the power of the DC-DC module is greater than the second threshold, then the output power of the inverter module is reduced. If the power of the DC-DC module is less than the first threshold, then the output power of the inverter module is increased; Repeat the steps of decreasing the output power of the inverter module if the power of the DC-DC module is greater than the second threshold, until the output power of the inverter module is increased if the power of the DC-DC module is less than the first threshold, until the power of the DC-DC module is within a preset range; Specifically, when the DC-DC module is in a discharging state, the power of the DC-DC module is positive; when the DC-DC module is in a charging state, the power of the DC-DC module is negative.

2. The photovoltaic grid-connected control method according to claim 1, characterized in that, The method further includes: If the power of the DC-DC module is within the preset range, the inverter module is controlled to output constant power according to the current power. The preset range is from a first threshold to a second threshold; the first threshold is less than the second threshold.

3. The photovoltaic grid-connected control method according to claim 1, characterized in that, If the power of the DC-DC module is greater than the second threshold, then reducing the output power of the inverter module includes: If the power of the DC-DC module is greater than the second threshold, the output power of the inverter module will be reduced by a preset step size. If the power of the DC-DC module is less than the first threshold, then increasing the output power of the inverter module includes: If the power of the DC-DC module is less than the first threshold and the output power of the inverter module is less than the preset maximum output power, then the output power of the inverter module is increased by the preset step size.

4. The photovoltaic grid-connected control method according to claim 3, characterized in that, The step of adjusting the output power of the inverter module to bring the power of the DC-DC module within the preset range if the power of the DC-DC module is not within the preset range further includes: If the power of the DC-DC module is less than the first threshold and the output power of the inverter module is not less than the preset maximum output power, then the output power of the inverter module is controlled to remain unchanged.

5. The photovoltaic grid-connected control method according to claim 4, characterized in that, The preset maximum output power is the power demand of the power grid minus the first deviation value.

6. The photovoltaic grid-connected control method according to any one of claims 3 to 5, characterized in that, If the power of the DC-DC module is not within a preset range, the output power of the inverter module is adjusted so that the power of the DC-DC module is within the preset range. The method further includes: Obtain the maximum power of the DC-DC module; Subtracting the second deviation value from the maximum power yields the second threshold; subtracting the third deviation value from the maximum power yields the first threshold. When the DC-DC module is in a discharging state, the second deviation value and the third deviation value are positive; when the DC-DC module is in a charging state, the second deviation value and the third deviation value are negative.

7. The photovoltaic grid-connected control method according to claim 6, characterized in that, The method further includes: When an anomaly is detected in the DC-DC module, the inverter module is controlled to operate in MPPT mode to perform maximum power point tracking on the photovoltaic module.

8. A control terminal, characterized in that, It includes a processor and a memory, the memory being used to store computer programs, and the processor being used to call and run the computer programs stored in the memory to perform the steps of the photovoltaic grid-connected control method as described in any one of claims 1 to 7.

9. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the photovoltaic grid-connected control method as described in any one of claims 1 to 7.

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