Battery SOC balance control method, inverter parallel operation system, equipment and medium

Abstract

The invention relates to the technical field of industrial control, in particular to a battery SOC balance control method, an inverter parallel operation system, equipment and a medium. The battery SOC equalization control method comprises the following steps: according to a preset equalization period, a current inverter obtains a battery actual SOC of a high-voltage battery connected with the current inverter, and provides the battery actual SOC for a preset host so as to obtain an average SOC provided by the preset host according to the battery actual SOC; obtaining an SOC difference value between the actual SOC and the average SOC of the battery, and obtaining a current correction value based on the SOC difference value; and obtaining the charging and discharging states of the inverter parallel operation system and the battery current threshold value of the high-voltage battery, and correcting the battery current threshold value by adopting the current correction value based on the charging and discharging states to obtain a final current threshold value. According to the invention, the balance of the SOC of the inverter parallel operation system is improved, the overhigh load of part of inverters is avoided, and the fault risk is reduced, so that the stability and reliability of the inverter parallel operation system are enhanced.

Description

Technical Field

[0001] The present invention relates to the field of industrial control technology, in particular to a battery SOC balancing control method, an inverter parallel system, equipment and a medium. Background Art

[0002] In the off-grid inverter parallel system, each inverter needs to be connected to a battery module separately. Due to factors such as light angle, light intensity, and number of photovoltaic panels, the photovoltaic power of each inverter will vary to a certain extent. At the same time, the hardware parameters and working characteristics of each inverter parallel system will also vary. These factors will cause the battery SOC of different battery modules to deviate within a certain period of time.

[0003] When the SOC of the battery connected to a certain inverter drops to the discharge cut-off point, the load of the entire parallel system needs to be shared by other online inverters. If the system has only two inverters, then all loads need to be provided by the other inverter, which will cause the load rate of the other inverter to increase sharply, and even trigger overload protection, eventually causing the entire system to lose power. Summary of the invention

[0004] The technical problem to be solved by the embodiments of the present invention is to provide a battery SOC balancing control method, an inverter parallel system, a device and a medium to solve the load imbalance problem caused by the accumulation of SOC deviation in the prior art.

[0005] The present invention discloses a battery SOC balancing control method, which is applied to an inverter parallel system, wherein the inverter parallel system comprises at least two groups of battery modules, each of which comprises: an inverter, and a photovoltaic panel and a high-voltage battery connected to the inverter; the inverters of two adjacent groups of battery modules are connected to each other;

[0006] The battery SOC equalization control method comprises the following steps:

[0007] According to the preset balancing cycle, the current inverter obtains the actual SOC of the high-voltage battery connected to itself, and provides the actual SOC of the battery to the preset host, so as to obtain the average SOC provided by the preset host according to the actual SOC of the battery;

[0008] Obtaining a SOC difference between the actual SOC of the battery and the average SOC, and obtaining a current correction value based on the SOC difference;

[0009] The charge and discharge state of the inverter parallel system and the battery current threshold of the high-voltage battery are obtained, and based on the charge and discharge state, the battery current threshold is corrected using the current correction value to obtain a final current threshold.

[0010] Optionally, the step of correcting the battery current threshold by using the current correction value based on the charge and discharge state includes:

[0011] If the battery is currently in a grid-connected charging state, the battery current threshold is subtracted from the current correction value to obtain the final current threshold;

[0012] If the battery is currently in a grid-connected discharge state, the battery current threshold is added with the current correction value to obtain the final current threshold.

[0013] Optionally, after the step of obtaining the final current threshold, the following steps are included:

[0014] The inverter current threshold of the current inverter is obtained, the smallest one of the inverter current threshold and the battery current threshold is used as a target threshold, and the final current threshold is limited by using the target threshold so that the final current threshold is between 0 and the target threshold.

[0015] Optionally, if the current state is grid-connected charging, after the step of obtaining the final current threshold, the method further includes:

[0016] Obtaining the photovoltaic charging power of the photovoltaic panel to which it is connected, obtaining the current charging power according to the final current threshold, and obtaining the excess charging amount based on the photovoltaic charging power and the current charging power;

[0017] Transmitting the excess charge to the microgrid of the inverter parallel system, so that other inverters can obtain at least part of the excess charge from the microgrid to charge the high-voltage batteries corresponding to the other inverters; or

[0018] After the step of obtaining the final current threshold, the method further includes:

[0019] When the current charging power is higher than the photovoltaic charging power, at least part of the excess power is obtained from the microgrid according to the difference between the photovoltaic charging power and the current charging power, and at least part of the excess charging power is provided to the corresponding high-voltage battery.

[0020] Optionally, the step of obtaining the excess charge amount from the microgrid includes:

[0021] Obtaining a total discharge current limit value, and obtaining an average discharge current limit value according to the total discharge current limit value;

[0022] At least a portion of the excess charge is obtained from the microgrid at a current lower than the average discharge current limit value.

[0023] Optionally, it is characterized in that the step of obtaining the current correction value based on the SOC difference includes:

[0024] A preset proportionality coefficient is obtained, and the proportionality coefficient is multiplied by the SOC difference to obtain the current correction value.

[0025] Optionally, the step of providing the actual SOC of the battery to a preset host comprises:

[0026] One inverter of at least one group of the battery modules is selected as the preset host.

[0027] An inverter parallel system, the inverter parallel system comprises at least one group of battery modules, each of the battery modules comprises: an inverter, and a photovoltaic panel and a high-voltage battery connected to the inverter; the inverters of two adjacent groups of battery modules are connected to each other;

[0028] The inverter is used to implement the battery SOC balancing control method as described above.

[0029] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the processor executes the steps of the method described above.

[0030] A power supply device comprises a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the above method.

[0031] Compared with the prior art, the battery SOC balancing control method provided by the embodiment of the present invention has the beneficial effect of calculating the average SOC according to the actual SOC of each battery module, and each inverter can calculate the difference between the actual SOC and the average SOC, and obtain the current correction value based on the difference. According to the charging and discharging state of the inverter parallel system and the battery current threshold of the high-voltage battery, the battery current threshold is adjusted using the current correction value to obtain the final current threshold. The current can be adjusted in time according to the actual situation, which helps to control the charging speed of each high-voltage battery accordingly, improve the balance of the SOC of the inverter parallel system, avoid excessive load on some inverters, reduce the risk of failure, and thus enhance the stability and reliability of the inverter parallel system. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The scheme of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, in which:

[0033] Figure 1 It is a flow chart of an embodiment of a battery SOC equalization control method provided by the present invention;

[0034] Figure 2 It is a structural schematic diagram of the inverter parallel system provided by the present invention;

[0035] Figure 3 is a flow chart of another embodiment of the battery SOC balancing control method provided by the present invention;

[0036] Figure 4 It is a flow chart of another embodiment of the battery SOC balancing control method provided by the present invention;

[0037] Figure 5 It is a structural schematic diagram of an embodiment of the energy supply device provided by the present invention;

[0038] Figure 6 It is a structural schematic diagram of an embodiment of a computer-readable storage medium provided by the present invention.

[0039] The reference numerals in the figures are:

[0040] 10. Inverter parallel system; 11. Battery module; 111. Inverter; 112. Photovoltaic panel; 113. High-voltage battery; 20. Energy supply device; 21. Processor; 22. Memory; 30. Computer-readable storage medium; 31. Computer program. DETAILED DESCRIPTION

[0041] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. Now, in conjunction with the accompanying drawings, the preferred embodiments of the present invention are described in detail.

[0042] Please refer to Figure 1 and Figure 2 , Figure 1 It is a flow chart of an embodiment of a battery SOC balancing control method provided by the present invention. Figure 2 Schematic diagram of the structure of the inverter parallel system provided by the present invention. Figure 2 As shown, the inverter parallel system 10 includes at least two battery modules 11, each battery module 11 includes an inverter 111, and a photovoltaic panel 112 and a high-voltage battery 113 connected to the inverter 111. The inverter 111 is used to convert the DC power stored in the high-voltage battery 113 into AC power to supply off-grid devices, and is also used to convert the DC power stored in the high-voltage battery 113 into AC power and connect it to the power grid to supply the power grid.

[0043] The inverter 111 parallel system in this embodiment supports off-grid mode. In off-grid mode, the inverter converts the DC power of the high-voltage battery 113 into AC power for off-grid equipment. When the high-voltage battery 113 needs to be charged, it can be charged through the photovoltaic panel 112. In the grid-connected mode, the inverter 111 converts the DC power of the high-voltage battery 113 into AC power and connects to the grid. In this mode, the inverter parallel system 10 can be charged through the grid or supply power to the grid, realizing a two-way flow of electric energy.

[0044] In this embodiment, each inverter 111 is connected to the corresponding high-voltage battery 113 and photovoltaic panel 112, which will cause the SOC of each high-voltage battery 113 to be unbalanced. It is necessary to regularly calibrate the SOC of the high-voltage battery 113 in each battery module 11 to ensure that the deviation between them is as small as possible, so as to reduce the SOC deviation between different battery modules 11, improve the power supply reliability of the entire inverter parallel system 10 in the off-grid parallel mode, and extend the power supply time to cope with emergencies such as power outages in the power grid.

[0045] exist Figure 2 In the inverter parallel system shown in the figure, the inverters 111 of the battery modules 11 of two adjacent groups are connected to each other and can communicate with each other to realize the present invention. Figure 1 Specifically, the two inverters 111 are connected via a CAN communication bus, the communication rate of the CAN bus is adjustable, and the bit rate used in this embodiment is 250 kpbs.

[0046] The battery SOC equalization control method provided by the present invention comprises the following steps:

[0047] S101: The current inverter obtains the actual SOC of the high-voltage battery connected to itself, and provides the actual SOC of the battery to the preset host, so as to obtain the average SOC provided by the preset host according to the actual SOC of the battery.

[0048] In a specific implementation scenario, Figure 2 The inverter parallel system shown includes multiple inverters, each of which is connected to a corresponding high-voltage battery. One inverter is selected from the multiple inverters as the preset host, and the remaining inverters are used as slaves of the host. The host can obtain the actual SOC of the high-voltage battery to which it is connected, and the slave obtains the actual SOC of the high-voltage battery to which it is connected, and transmits it to the preset host through the connection between each other, so that the host can obtain the actual SOC of all high-voltage batteries in the inverter parallel system. Add all the actual SOCs and divide them by the number of high-voltage batteries to obtain the average SOC. The host sends the average SOC to each slave through the connection between each inverter. Both the host and the slave can obtain the average SOC.

[0049] S102: Obtaining a SOC difference between an actual SOC of the battery and an average SOC, and obtaining a current correction value based on the SOC difference.

[0050] In a specific implementation scenario, for each inverter, the actual SOC of the high-voltage battery connected to the inverter and the received / calculated average SOC are obtained, and the SOC difference between the actual SOC of the battery and the average SOC is obtained. The SOC difference reflects the difference between the actual SOC of the battery and the average SOC. For example, if the SOC difference is positive, it means that the actual SOC of the high-voltage battery exceeds the average SOC. If the battery is in a charging state, the charging power needs to be reduced. If the battery is in a discharging state, the discharging power needs to be increased, thereby narrowing the gap between the actual SOC of the battery and the average SOC. For another example, if the SOC difference is negative, it means that the actual SOC of the high-voltage battery is lower than the average SOC. If the battery is in a charging state, the charging power needs to be increased. If the battery is in a discharging state, the discharging power needs to be reduced, thereby narrowing the gap between the actual SOC of the battery and the average SOC.

[0051] A current correction value is obtained based on the SOC difference, and the current correction value is used to correct the charge and discharge current of the high-voltage battery, thereby adjusting the SOC of the high-voltage battery to narrow the gap between the SOCs of the various high-voltage batteries.

[0052] In one embodiment, the current correction value can be obtained according to the SOC difference based on the proportional coefficient correction method. The proportional coefficient is a pre-set parameter used to adjust the magnitude of the current correction value. For example, the current correction value = proportional coefficient × SOC difference.

[0053] In other implementation scenarios, the current correction value can also be obtained according to other methods. For example, the PID control method, the PID controller (proportional-integral-differential controller) can calculate the current correction value according to the size of the SOC difference, combining the three parts of proportion, integration and differentiation. The PID controller can be adjusted according to the real-time state of the system, and has good stability and dynamic performance. For another example, the fuzzy logic control method, the fuzzy logic controller can infer the corresponding current correction value according to the fuzzy rules and the input SOC difference. Fuzzy logic can handle uncertainty and ambiguity. For another example, a neural network can be used to input the SOC difference as a feature according to a trained model, and the corresponding current correction value is output. Neural networks can learn complex nonlinear relationships and are suitable for control problems that require higher precision and complexity.

[0054] S103: Acquire the charge and discharge state of the inverter parallel system and the battery current threshold of the high-voltage battery, and based on the charge and discharge state, use the current correction value to correct the battery current threshold to obtain a final current threshold.

[0055] In a specific implementation scenario, a battery current threshold of a high-voltage battery is obtained, and the battery current threshold is used to limit the amplitude of the input / output current during charging / discharging of the high-voltage battery. The battery current threshold is used to limit the amplitude of the input / output current to protect the safety of the high-voltage battery.

[0056] In this implementation scenario, the charging and discharging power of the high-voltage battery is adjusted by adjusting the amplitude of the input / output current to narrow the difference in the SOC of each high-voltage battery. According to the analysis above, the power adjustment strategy for the high-voltage battery is inconsistent in the charging state and the discharging state, so the current adjustment also needs to be set according to the specific charging and discharging state. Therefore, in this embodiment, the charging and discharging state of the inverter parallel system is obtained, and based on the charging and discharging state, the battery current threshold is corrected using the current correction value to obtain the final current threshold.

[0057] If the battery is currently in a grid-connected charging state, the battery current threshold is subtracted from the current correction value to obtain the final current threshold. If the battery is currently in a grid-connected discharging state, the battery current threshold is added to the current correction value to obtain the final current threshold.

[0058] Specifically, if the battery is currently in a grid-connected charging state and the SOC difference is positive, the corresponding current correction value is positive, and the final current threshold obtained by subtracting the current correction value from the battery current threshold is smaller, so that the upper limit of the charging current of the high-voltage battery is lowered, and the charging power is reduced, so that the growth rate of the high-voltage battery's excessively high SOC is slowed down. If the SOC difference is negative, the corresponding current correction value is negative, and the final current threshold obtained by subtracting the current correction value from the battery current threshold is larger, so that the upper limit of the charging current of the high-voltage battery is increased, and the charging power is increased, so that the growth rate of the low SOC of the high-voltage battery is faster. In this way, by slowing down the growth rate of the excessively high SOC and accelerating the growth rate of the low SOC, the SOC balance of all high-voltage batteries can be achieved.

[0059] If the current state is grid-connected discharge, and the SOC difference is positive, the corresponding current correction value is positive, and the final current threshold obtained by adding the battery current threshold to the current correction value is larger, so that the discharge current upper limit of the high-voltage battery is increased, and the discharge power is increased, so that the high-voltage battery's excessively high SOC is reduced faster. If the SOC difference is negative, the corresponding current correction value is negative, and the final current threshold obtained by adding the battery current threshold to the current correction value is smaller, so that the discharge current upper limit of the high-voltage battery is reduced, and the charging power is reduced, so that the high-voltage battery's lower SOC is reduced slower. In this way, by increasing the reduction rate of the excessively high SOC and reducing the reduction rate of the lower SOC, the SOC balance of all high-voltage batteries can be achieved. This strategy can ensure that the SOC of each battery module is in a relatively balanced state, improving the performance and stability of the system.

[0060] In other implementation scenarios, each inverter has an inverter current threshold, which is used to limit the current size of the inverter input / output to protect the inverter. In order to protect the inverter and the high-voltage battery, for each battery module, the inverter current threshold of the inverter and the battery current threshold of the high-voltage battery are obtained, and the smallest of the inverter current threshold and the battery current threshold is used as the target threshold. The target threshold is used to limit the final current threshold so that the final current threshold is between 0 and the target threshold. In other words, if the final current threshold has not reached or equal to the target threshold, the final current threshold remains unchanged. If the final current threshold is negative, it is set to 0 to ensure that no negative value occurs. If the final current threshold has exceeded the target threshold, it is set to the target threshold size to avoid exceeding the set limit. In this way, it can be ensured that the inverter and high-voltage battery of each battery module are effectively protected, so that its various components can work normally, which helps to maintain the stability and reliability of the system while protecting key equipment from damage.

[0061] In the present invention, SOC balancing control is only performed for charging and discharging in the grid-connected state, but not for charging and discharging in the off-grid state. The specific reasons are as follows:

[0062] In the off-grid discharge state, if SOC balancing is achieved by limiting the discharge current of the high-voltage battery, once the load exceeds the battery discharge limit, the DC bus voltage in the system will drop, and may even cause the equipment or machines in the system to fail to operate normally. This is because the battery's discharge capacity is limited and cannot meet the needs of the system, causing the system to fail to operate normally and triggering the machine protection mechanism. If the parallel current balancing strategy is changed to uneven current, some inverters will trigger overload protection first, and other inverters will need to bear more loads, which may cause the entire system to protect. Uneven current will also introduce high-frequency circulating current, affecting power quality and system stability.

[0063] In the off-grid charging state, limiting the photovoltaic energy input of the photovoltaic panel to achieve SOC balance will cause the system revenue to be damaged. Photovoltaic energy is the main charging source of the system. Limiting its input will reduce the system's income and affect the system's economy. The off-grid system should give priority to the use of photovoltaic energy to extend the power supply time, but limiting the photovoltaic energy input to achieve SOC balance will violate this principle, resulting in the system's inability to maximize the use of renewable energy.

[0064] In general, the problem with off-grid discharge SOC balancing and off-grid charging SOC balancing is that the implementation of the SOC balancing strategy will cause serious challenges in system stability, economy, and power quality. These problems may lead to serious consequences such as abnormal system operation, reduced revenue, and equipment damage. Therefore, not opening the off-grid SOC balancing function can avoid these problems and ensure the reliability and economy of the system.

[0065] In this embodiment, steps S101-S103 are executed according to a preset cycle to achieve real-time SOC balancing of the entire inverter parallel system, so as to ensure that the difference in SOC of each high-voltage battery is as small as possible at any time, avoid partial inverter overload problems caused by SOC imbalance, and thus improve the stability and reliability of the entire inverter parallel system.

[0066] From the above description, it can be seen that in this embodiment, the average SOC is calculated according to the actual SOC of each battery module, each inverter can calculate the difference between the actual SOC and the average SOC, and obtain the current correction value based on the difference, and the battery current threshold is adjusted according to the charging and discharging state of the inverter parallel system and the battery current threshold of the high-voltage battery using the current correction value to obtain the final current threshold. The current can be adjusted in time according to the actual situation, which helps to control the charging speed of each high-voltage battery accordingly, improve the balance of the SOC of the inverter parallel system, avoid excessive load on some inverters, reduce the risk of failure, and thus enhance the stability and reliability of the inverter parallel system.

[0067] Please refer to Figure 2 and Figure 3 , Figure 3 FIG. 1 is a flow chart of another embodiment of the battery SOC balancing control method provided by the present invention. The battery SOC balancing control method provided by the present invention also includes the following steps:

[0068] S201: Obtain the photovoltaic charging power of the photovoltaic panel to which it is connected, obtain the current charging power according to the final current threshold, and obtain the excess charging amount based on the photovoltaic charging power and the current charging power.

[0069] In a specific implementation scenario, when the inverter parallel system is in the grid-connected charging state, after obtaining the final current threshold, since the final current threshold may limit the charging power, for example, when the actual SOC of the battery module is higher than the average SOC, it is necessary to limit the charging current to reduce the SOC growth rate of the high-voltage battery. At this time, the charging power of the high-voltage battery is low. At this time, the photovoltaic panel of the same battery module as the high-voltage battery collects light energy and converts it into electrical energy that exceeds the current demand of the high-voltage battery, and there may be an excess of electrical energy.

[0070] In order to make full use of the excess electric energy, the current charging power of the high-voltage battery can be obtained based on the photovoltaic charging power of the photovoltaic panel and the final current threshold currently obtained. If the current charging power is lower than the photovoltaic charging power, it means that the photovoltaic panel provides excess electric energy. The excess charging power can be obtained based on the photovoltaic charging power and the current charging power, and the excess charging amount can be obtained based on the excess charging power.

[0071] S202: Transmitting the excess charge to the microgrid of the inverter parallel system, so that other inverters can obtain at least part of the excess charge from the microgrid to charge the high-voltage batteries corresponding to the other inverters.

[0072] In a specific implementation scenario, the excess charge is transmitted to the microgrid of the inverter parallel system, so that other inverters can obtain the excess charge from the microgrid to charge the high-voltage batteries corresponding to other inverters. This mechanism of sharing charge helps to optimize the charging state of each high-voltage battery in the inverter parallel system and improve the overall efficiency and performance of the system.

[0073] A microgrid refers to a local power network formed before the output sides of multiple machines in the entire inverter parallel system merge into the actual power grid, that is, it means that the inverter parallel system in this embodiment realizes overall anti-reverse flow, and the total CT (Current transformer) sampling port is a parallel power network. In this microgrid, multiple inverters are operated in parallel to form a local power network. This microgrid can be operated independently or connected to the actual power grid. In this microgrid, inverters can share energy, operate in coordination, and ensure the stability and safety of the system through the designed control strategy. The output current of all inverters will be sampled and then monitored and controlled by CT. By monitoring and analyzing these current data, the inverter parallel system can realize the overall anti-reverse flow function, ensure that the current output by the inverter parallel system to the power grid meets the requirements, and avoid the occurrence of reverse flow.

[0074] For example, when the actual SOC of the battery module is lower than the average SOC, it is necessary to increase the charging current to speed up the SOC growth rate of the high-voltage battery. At this time, the high-voltage battery requires a higher charging power. At this time, the photovoltaic panel of the same battery module as the high-voltage battery collects light energy and converts it into electrical energy that cannot meet the current needs of the high-voltage battery, which will not only affect the charging efficiency of the battery module, but also affect the SOC balancing effect of the entire inverter parallel system. At this time, the inverter of this group of battery modules obtains at least part of the excess power through the microgrid to meet the current charging needs of the battery module, which can better maintain the SOC balance of the entire inverter parallel system, and can also make full use of the power provided by each photovoltaic panel, thereby improving resource utilization.

[0075] Please refer to Figure 4 and Figure 2 , Figure 4 FIG. 1 is a flow chart of another embodiment of the battery SOC balancing control method provided by the present invention. The battery SOC balancing control method provided by the present invention also includes the following steps:

[0076] S301: When the current charging power is higher than the photovoltaic charging power, at least part of the excess power is obtained from the microgrid according to the difference between the photovoltaic charging power and the current charging power, and at least part of the excess charging power is provided to the corresponding high-voltage battery.

[0077] In a specific implementation scenario, when the current charging power of a battery module is higher than the photovoltaic charging power, it means that the power provided by the current photovoltaic panel cannot meet the charging demand of the high-voltage battery. Therefore, the actual charging amount actually required is obtained according to the difference between the photovoltaic charging power and the current charging power, and at least part of the excess power is obtained from the microgrid as the actual charging amount. The actual charging amount is charged into the high-voltage battery. This can not only meet the charging demand of the current battery module, but also reasonably use the excess power of other battery modules.

[0078] The current inverter parallel system has the anti-reverse flow function turned on. It is necessary to adjust the maximum average grid-connected current of all battery modules according to the current fed into the grid by the inverter parallel system. The purpose of this is to ensure that the inverter parallel system can still meet the anti-reverse flow requirements when the excess energy generated by the photovoltaic panels is used to charge other battery modules.

[0079] In this embodiment, the electric energy output by the inverter fed into the grid is defined as backflow, and the anti-backflow function is to prevent the excess electric energy of the inverter system from being fed into the grid, affecting the quality of the grid. When the energy output by the photovoltaic panel exceeds the demand of the corresponding high-voltage battery, it can be fed into the microgrid of the inverter parallel system, but the interface where the entire inverter parallel system is connected to the grid still meets the system-level anti-backflow requirements. That is to say, if there is excess power after coordinating the power within the entire inverter parallel system (for example, all high-voltage batteries are fully charged, but there is still power left from the photovoltaic panel), it is necessary to further restrict it according to the anti-backflow requirements.

[0080] In order to improve the safety of the inverter parallel system, the inverter parallel system will adjust the average discharge current limit value of all machines. In this implementation scenario, the total discharge current limit value is obtained, and the average discharge current limit value is obtained according to the total discharge current limit value; the inverter needs to obtain at least part of the excess charge from the microgrid with a current lower than the average discharge current limit value.

[0081] In this way, the inverter parallel system can effectively utilize the excess energy generated by the photovoltaic panels while ensuring that the system operation meets the requirements of anti-backflow, thereby improving the energy utilization efficiency and stability of the inverter parallel system.

[0082] From the above description, it can be seen that in this embodiment, when the power generated by the photovoltaic panel exceeds the charging demand of the corresponding high-voltage battery, the excess power is provided to the microgrid of the inverter grid-connected system, so that the battery modules whose power generated by the photovoltaic panel cannot meet the charging demand of the high-voltage battery can obtain the excess power from the microgrid to charge their own high-voltage batteries. This can better maintain the SOC balance of the entire inverter parallel system and make full use of the power provided by each photovoltaic panel, thereby improving resource utilization.

[0083] See also Figure 5 , Figure 5 2 is a schematic diagram of the structure of an embodiment of the energy supply device provided by the present invention. The energy supply device 20 includes a processor 21 and a memory 22. The processor 21 is coupled to the memory 22. The memory 22 stores a computer program, and the processor 21 executes the computer program when working to implement the method as described above. The detailed steps can be referred to above and will not be repeated here.

[0084] See also Figure 6 , Figure 63 is a schematic diagram of the structure of an embodiment of the computer-readable storage medium provided by the present invention. The computer-readable storage medium 30 stores at least one computer program 31, which is used to be executed by the processor to implement the above method. The detailed steps can be found above and will not be repeated here. In one embodiment, the computer-readable storage medium 30 can be a storage chip, a hard disk, or a mobile hard disk or a USB flash drive, a CD, or other readable and writable storage tools in the terminal, or a server, etc.

[0085] The storage medium may be implemented by any type of volatile or non-volatile storage device, or a combination thereof. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROMElectrically Erasable Programmable Read-Only Memory), a magnetic random access memory (FRAM), a flash memory, a magnetic surface memory, an optical disc, or a compact disc read-only memory (CD-ROM); the magnetic surface memory may be a disk memory or a tape memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example but not limitation, many forms of RAM are available, such as static random access memory (SRAM), synchronous static random access memory (SSRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDRSDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), direct memory bus random access memory (DRRAM). The storage media described in the embodiments of the present invention are intended to include, but are not limited to, these and any other suitable types of memory.

[0086] In the several embodiments provided by the present invention, it should be understood that the disclosed systems and methods can be implemented in other ways. The device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as: multiple units or components can be combined, or can be integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the components shown or discussed can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0087] The units described above as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units; some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0088] In addition, all functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may be separately used as a unit, or two or more units may be integrated into one unit; the above-mentioned integrated units may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0089] A person skilled in the art can understand that: all or part of the steps of implementing the above method embodiment can be completed by hardware related to program instructions, and the aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it executes the steps of the above method embodiment; and the aforementioned storage medium includes: mobile storage devices, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), disks or optical disks, etc. Various media that can store program codes.

[0090] Alternatively, if the above-mentioned integrated unit of the present invention is implemented in the form of a software function module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiment of the present invention can be essentially or partly reflected in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as mobile storage devices, ROM, RAM, magnetic disks or optical disks.

[0091] The methods disclosed in the several method embodiments provided by the present invention can be arbitrarily combined without conflict to obtain new method embodiments.

[0092] The features disclosed in several product embodiments provided by the present invention can be arbitrarily combined without conflict to obtain new product embodiments.

[0093] The features disclosed in several method or device embodiments provided by the present invention can be arbitrarily combined without conflict to obtain new method embodiments or device embodiments.

[0094] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art of the present invention, several equivalent substitutions or obvious variations can be made without departing from the concept of the present invention, and the performance or use is the same, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A battery SOC balancing control method, characterized in that: Applied to an inverter parallel system, the inverter parallel system comprises at least two groups of battery modules, each of the battery modules comprises: an inverter, and a photovoltaic panel and a high-voltage battery connected to the inverter; the inverters of two adjacent groups of the battery modules are connected to each other; The battery SOC equalization control method comprises the following steps: According to the preset balancing cycle, the current inverter obtains the actual SOC of the high-voltage battery connected to itself, and provides the actual SOC of the battery to the preset host, so as to obtain the average SOC provided by the preset host according to the actual SOC of the battery; Obtaining a SOC difference between the actual SOC of the battery and the average SOC, and obtaining a current correction value based on the SOC difference; The charge and discharge state of the inverter parallel system and the battery current threshold of the high-voltage battery are obtained, and based on the charge and discharge state, the battery current threshold is corrected using the current correction value to obtain a final current threshold.

2. The battery SOC equalization control method according to claim 1, characterized in that: The step of correcting the battery current threshold by using the current correction value based on the charge and discharge state includes: If the battery is currently in a grid-connected charging state, the battery current threshold is subtracted from the current correction value to obtain the final current threshold; If the battery is currently in a grid-connected discharge state, the battery current threshold is added with the current correction value to obtain the final current threshold.

3. The battery SOC equalization control method according to claim 2, characterized in that: After the step of obtaining the final current threshold, the method further comprises: The inverter current threshold of the current inverter is obtained, the smallest one of the inverter current threshold and the battery current threshold is used as a target threshold, and the final current threshold is limited by using the target threshold so that the final current threshold is between 0 and the target threshold.

4. The battery SOC equalization control method according to claim 2, characterized in that: If the current state is grid-connected charging, after the step of obtaining the final current threshold, the method further includes: Obtaining the photovoltaic charging power of the photovoltaic panel to which it is connected, obtaining the current charging power according to the final current threshold, and obtaining the excess charging amount based on the photovoltaic charging power and the current charging power; Transmitting the excess charge to the microgrid of the inverter parallel system, so that other inverters can obtain at least part of the excess charge from the microgrid to charge the high-voltage batteries corresponding to the other inverters; or After the step of obtaining the final current threshold, the method further includes: When the current charging power is higher than the photovoltaic charging power, at least part of the excess power is obtained from the microgrid according to the difference between the photovoltaic charging power and the current charging power, and at least part of the excess charging power is provided to the corresponding high-voltage battery.

5. The battery SOC equalization control method according to claim 4, characterized in that: The step of obtaining the excess charge amount from the microgrid comprises: Obtaining a total discharge current limit value, and obtaining an average discharge current limit value according to the total discharge current limit value; At least a portion of the excess charge is obtained from the microgrid at a current lower than the average discharge current limit value.

6. The battery SOC equalization control method according to any one of claims 1 to 5, characterized in that: The step of obtaining a current correction value based on the SOC difference comprises: A preset proportionality coefficient is obtained, and the proportionality coefficient is multiplied by the SOC difference to obtain the current correction value.

7. The battery SOC equalization control method according to any one of claims 1 to 5, characterized in that: The step of providing the actual SOC of the battery to the preset host comprises: One inverter of at least one group of the battery modules is selected as the preset host.

8. An inverter parallel system, characterized in that: The inverter parallel system includes at least one group of battery modules, each of which includes: an inverter, and a photovoltaic panel and a high-voltage battery connected to the inverter; the inverters of two adjacent groups of battery modules are connected to each other; The inverter is used to implement the battery SOC balancing control method according to any one of claims 1 to 7.

9. A computer-readable storage medium, characterized in that: A computer program is stored, and when the computer program is executed by a processor, the processor is caused to perform the steps of the method according to any one of claims 1 to 7.

10. An energy supply device, characterized in that: The method comprises a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method according to any one of claims 1 to 7.

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