Charging and discharging control method of energy storage system and energy storage system

Abstract

The invention discloses a charging and discharging control method of an energy storage system and the energy storage system. The energy storage system comprises a plurality of charging and discharging control modules and a plurality of groups of electric piles, and each electric pile comprises a plurality of batteries; each charging and discharging control module is connected with one group of electric piles, and a plurality of electric piles in the same group are connected in parallel; the charging and discharging control method of the energy storage system comprises the following steps: acquiring charging and discharging voltages of a plurality of batteries in a galvanic pile; determining an operation interval of the galvanic pile according to a relationship between the charge-discharge voltage and a preset voltage; and controlling the charge-discharge control module to reduce power or cut off the stack according to the operation interval of the stack. According to the technical scheme provided by the embodiment of the invention, the operation interval of the galvanic pile is judged according to the relationship between the charging and discharging voltage of the battery in the galvanic pile and the preset voltage. When the galvanic pile is in an operation interval which is not fully charged, reducing the power of the charging and discharging control module to further charge the galvanic pile; and the electric pile is cut off when the electric pile cannot be continuously charged, so that the utilization rate of the capacity of the electric pile is improved, and the charge-discharge efficiency of the energy storage system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage, and particularly to a charge and discharge control method for an energy storage system and an energy storage system. Background Art

[0002] At present, an energy storage system usually charges and discharges a stack to store or release electric energy. When the existing energy storage system controls the charge and discharge of the stack, it is likely to cause the problem that the capacity of the stack is not fully released, affecting the charge and discharge efficiency. Summary of the Invention

[0003] The present invention provides a charge and discharge control method for an energy storage system and an energy storage system, so as to improve the utilization rate of the stack capacity and the charge and discharge efficiency of the energy storage system.

[0004] According to one aspect of the present invention, there is provided a charge and discharge control method for an energy storage system. The energy storage system includes a plurality of charge and discharge control modules and multiple groups of stacks, and each stack includes a plurality of batteries; each of the charge and discharge control modules is connected to a group of the stacks, and the multiple stacks in the same group are connected in parallel;

[0005] The charge and discharge control method of the energy storage system includes:

[0006] Obtaining the charge and discharge voltages of the multiple batteries in the stack;

[0007] Determining the operating range of the stack according to the relationship between the charge and discharge voltage and a preset voltage;

[0008] Controlling the charge and discharge control module to reduce the power or cut off the stack according to the operating range of the stack.

[0009] Optionally, obtaining the charge and discharge voltages of the multiple batteries in the stack includes:

[0010] Obtaining the charge voltage and the discharge voltage of each battery in the stack.

[0011] Optionally, determining the operating range of the stack according to the relationship between the charge and discharge voltage and a preset voltage includes:

[0012] Sorting the multiple charge voltages from large to small;

[0013] Determining the operating range of the stack according to the relationship between the first n charge voltages and the preset voltage, where n is an integer greater than 0.

[0014] Optionally, the preset voltage includes a first preset voltage and a second preset voltage, and the first preset voltage is greater than the second preset voltage. Determining the operating range of the stack according to the relationship between the first n charge voltages and the preset voltage includes:

[0015] If the maximum value of the charging voltage is greater than or equal to the first preset voltage, it is determined that the stack is in the damage range;

[0016] If the first n charging voltages are all greater than or equal to the second preset voltage and all less than the first preset voltage, it is determined that the stack is in the high hydrogen production range.

[0017] Optionally, controlling the charge-discharge control module to reduce power or disconnect the stack according to the operating range of the stack includes:

[0018] If the stack is in the damage range, control the charge-discharge control module to reduce power;

[0019] Return to execute the step of obtaining the charging voltage and discharging voltage of each cell in the stack, and execute sequentially. If the stack is in the damage range or the high hydrogen production range, disconnect the stack.

[0020] Optionally, controlling the charge-discharge control module to reduce power or disconnect the stack according to the operating range of the stack includes:

[0021] If the stack is in the high hydrogen production range, control the charge-discharge control module to reduce power;

[0022] Return to execute the step of obtaining the charging voltage and discharging voltage of each cell in the stack, and execute sequentially. If the stack is in the damage range or the high hydrogen production range, disconnect the stack.

[0023] Optionally, the preset voltage further includes a third preset voltage. After obtaining the charging voltage and discharging voltage of each cell in the stack, it further includes:

[0024] Control the charge-discharge control module to reduce power or disconnect the stack according to the relationship between the minimum value of multiple discharging voltages and the third preset voltage.

[0025] Optionally, controlling the charge-discharge control module to reduce power or disconnect the stack according to the relationship between the minimum value of multiple discharging voltages and the third preset voltage includes:

[0026] If the minimum value of multiple discharging voltages is less than or equal to the third preset voltage, control the charge-discharge control module to reduce power;

[0027] Return to execute the step of obtaining the charge-discharge voltages of multiple cells in the stack, and execute sequentially. If the minimum value of multiple discharging voltages in the stack is still less than or equal to the third preset voltage, disconnect the stack.

[0028] Optionally, after removing the stack, the method further includes:

[0029] If the number of removed stacks in the same group is equal to the preset number of removed stacks, stop the charge-discharge control.

[0030] According to another aspect of the present invention, there is provided an energy storage system, which performs charge-discharge control by using the charge-discharge control method of the energy storage system according to any one of the first aspects.

[0031] The technical solution provided by the embodiments of the present invention obtains the charge-discharge voltages of multiple batteries in the stack, and determines the operating range of the stack according to the relationship between the charge-discharge voltages of the multiple batteries in the stack and the preset voltage. When the stack is in the operating range where it is not fully charged, the power of the charge-discharge control module is reduced to further charge the uncharged batteries; when the stack can no longer be charged, the corresponding stack is removed. Moreover, multiple stacks in the same group are connected in parallel. When the charge-discharge control module controls a single stack, it does not affect the charge-discharge of other stacks, thereby improving the utilization rate of the stack capacity and the charge-discharge efficiency of the energy storage system.

[0032] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. Description of the Drawings

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0034] Figure 1 is a schematic structural diagram of an energy storage system provided by an embodiment of the present invention;

[0035] Figure 2 is a flowchart of a charge-discharge control method for an energy storage system provided by an embodiment of the present invention;

[0036] Figure 3 is a flowchart of another charge-discharge control method for an energy storage system provided by an embodiment of the present invention;

[0037] Figure 4 is a flowchart of another charge-discharge control method for an energy storage system provided by an embodiment of the present invention;

[0038] Figure 5 is a schematic diagram of a charge-discharge voltage curve of a battery in an energy storage system provided by an embodiment of the present invention;

[0039] Figure 6 It is a flowchart of a charge-discharge control method for another energy storage system provided by an embodiment of the present invention;

[0040] Figure 7 It is a flowchart of a charge-discharge control method for another energy storage system provided by an embodiment of the present invention;

[0041] Figure 8 It is a flowchart of a charge-discharge control method for another energy storage system provided by an embodiment of the present invention;

[0042] Figure 9 It is a flowchart of a charge-discharge control method for another energy storage system provided by an embodiment of the present invention;

[0043] Figure 10 It is a flowchart of a charge-discharge control method for another energy storage system provided by an embodiment of the present invention. Detailed implementation manners

[0044] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0045] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such used data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order different from those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily need to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0046] Figure 1 It is a schematic structural diagram of an energy storage system provided by an embodiment of the present invention, Figure 2 It is a flowchart of a charge-discharge control method for an energy storage system provided by an embodiment of the present invention. Refer to Figure 1 and Figure 2, the energy storage system includes multiple charge and discharge control modules 100 and multiple stacks of cells 200. Each stack of cells 200 includes multiple batteries 300; each charge and discharge control module 100 is connected to one stack of cells 200, and multiple stacks of cells 200 within the same group are connected in parallel.

[0047] Specifically, the energy storage system may include multiple charge and discharge control modules 100. The charge and discharge control module 100 can be a DC-DC converter. The charge and discharge control module 100 is responsible for converting the external DC voltage into a voltage that can supply power for charging or discharging the stack of cells 200. Each stack of cells 200 can be composed of multiple batteries 300 connected in series. Exemplarily, as Figure 1 shown, the energy storage system includes two charge and discharge control modules 100 and ten stacks of cells 200. Among them, five stacks of cells 200 form a group. Each charge and discharge control module 100 correspondingly controls one group of stacks of cells 200. Each stack of cells 200 includes 30 batteries 300 connected in series. One charge and discharge control module 100 is responsible for controlling the charging and discharging of multiple stacks of cells 200 within the same group, avoiding the charge and discharge control module 100 being overloaded and affecting the charge and discharge efficiency of the energy storage system. Multiple stacks of cells 200 within the same group are connected in parallel with each other. Thus, when the charge and discharge control module 100 controls a single stack of cells 200, it does not affect the charging and discharging of other stacks of cells 200 within the same group, thereby improving the utilization rate of the stack capacity and the charge and discharge efficiency of the stack of cells.

[0048] The charge and discharge control method of the energy storage system includes:

[0049] S110. Obtain the charge and discharge voltages of multiple batteries within the stack of cells.

[0050] Specifically, due to the influence of temperature differences inside the stack of cells, the degree of battery aging, and the differences in battery physical properties, during the same charge and discharge process, there are also differences in the charge and discharge voltages of each battery; the charge and discharge voltages of each battery during charging and discharging within the stack of cells can be collected and obtained through devices such as a battery management system or a voltage sensor.

[0051] S120. Determine the operating range of the stack of cells according to the relationship between the charge and discharge voltage and the preset voltage.

[0052] Specifically, factors such as the charging rate of the battery and the reaction rate of the electrolyte inside the battery at different charge and discharge voltages will cause the battery itself to be in different states. The preset voltage can be the voltage value at the moment when the battery state changes during the charge and discharge process of the battery. The operating range of the stack of cells can be an interval divided for the charge and discharge state of the entire stack of cells based on the states of multiple batteries within the stack of cells. Therefore, the charge and discharge state of the stack of cells can be judged according to the relationship between the charge and discharge voltages of multiple batteries within the stack of cells and the preset voltage, thereby judging the operating range of the stack of cells.

[0053] S130. Control the charge-discharge control module to reduce the power or cut off the stack according to the operating range of the stack.

[0054] Specifically, when the stack is in different operating ranges, the states of each cell in the stack are different. In the range where the cells in the stack are not fully charged, the stack can continue to be charged normally; when some cells in the stack are not fully charged while some cells are already fully charged or overcharged, the power of the charge-discharge control module can be reduced as needed to charge the cells that are not fully charged; in the range where most cells in the stack can no longer be charged, the corresponding stack is cut off.

[0055] The technical solution provided by the embodiment of the present invention obtains the charge-discharge voltages of multiple cells in the stack, and determines the operating range of the stack according to the relationship between the charge-discharge voltages of multiple cells in the stack and the preset voltage. When the stack is in the operating range where it is not fully charged, the power of the charge-discharge control module is reduced to further charge the cells that are not fully charged; when the stack can no longer be charged, the corresponding stack is cut off. Moreover, multiple stacks in the same group are connected in parallel. When the charge-discharge control module controls a single stack, it does not affect the charge and discharge of other stacks, thereby improving the utilization rate of the stack capacity and the charge-discharge efficiency of the energy storage system.

[0056] Optionally, Figure 3 is a flowchart of another charge-discharge control method for an energy storage system provided by an embodiment of the present invention. On the basis of the above embodiment, refer to Figure 3 . The charge-discharge control method for this energy storage system includes:

[0057] S210. Obtain the charging voltage and discharging voltage of each cell in the stack.

[0058] Specifically, there are significant differences in the voltage changes of the cells in the stack under the charging state and the discharging state. Therefore, it is necessary to respectively and real-time obtain the charging voltage of each cell in the stack under the charging state and the discharging voltage of each cell under the discharging state; thereby judging the operating range of the stack under the charging state according to the charging voltage, and judging the discharging state of the stack according to the discharging voltage.

[0059] S220. Determine the operating range of the stack according to the relationship between the charge-discharge voltage and the preset voltage.

[0060] S230. Control the charge-discharge control module to reduce the power or cut off the stack according to the operating range of the stack.

[0061] The technical solution provided by the present invention determines the operating range of the stack in the charging state according to the relationship between the charging voltage and the preset voltage, and determines the operating state of the stack during discharging according to the relationship between the discharging voltage and the preset voltage by obtaining the charging voltage of the battery in the stack in the charging state and the discharging voltage in the discharging state, thereby controlling the charge and discharge control module to reduce the power or cut off the stack in the charge and discharge state, improving the charge and discharge efficiency of the stack.

[0062] Optionally, Figure 4 is a flowchart of another charge and discharge control method for an energy storage system provided by an embodiment of the present invention. Figure 5 is a schematic diagram of the charge and discharge voltage curves of the battery in an energy storage system provided by an embodiment of the present invention. On the basis of the above embodiment, see Figure 4 and Figure 5 . The charge and discharge control method of the energy storage system includes:

[0063] S310. Obtain the charging voltage and discharging voltage of each battery in the stack.

[0064] S320. Sort the multiple charging voltages from largest to smallest.

[0065] Specifically, each stack includes a plurality of batteries connected in series, and the charging voltages of each battery in the charging state are not exactly the same. Exemplarily, as Figure 1 shown in the stack 200, 30 batteries 300 are provided in each stack 200, and a total of 30 charging voltages are obtained. The 30 obtained charging voltages need to be sorted in descending order. Sorting the charging voltages of each battery in the stack from largest to smallest is convenient for mastering the distribution of the charging states of the batteries in the stack on the one hand, and is convenient for further judging the operating range of the stack according to the charging states of the batteries on the other hand.

[0066] S330. Determine the operating range of the stack according to the relationship between the first n charging voltages and the preset voltage, where n is an integer greater than 0.

[0067] Specifically, as Figure 5As shown in the figure, the abscissa SOC represents the battery's state of charge, and the ordinate U represents the battery's charging voltage or discharging voltage. Curve L1 is the curve of the battery's charging voltage changing with the state of charge, and curve L2 is the curve of the battery's discharging voltage changing with the state of charge. In the charging state, the battery's charging voltage gradually increases as the battery's state of charge increases. It can be seen that the higher the battery's charging voltage, the closer the battery is to the fully charged state; the lower the battery's charging voltage, the relatively more capacity remains for further charging. Overcharging the battery will affect the battery's lifespan and pose significant safety issues. Therefore, after sorting the charging voltages of each battery in the stack from largest to smallest, the operating range of the stack can be determined based on the relationship between the first n relatively large charging voltages and a preset voltage. Exemplarily, as Figure 1 shown in the stack 200, each stack 200 is provided with 30 batteries 300, and the operating range of the stack 200 can be determined based on the relationship between the first 5 relatively large charging voltages and the preset voltage.

[0068] S340. Control the charge and discharge control module to reduce the power or disconnect the stack according to the operating range of the stack.

[0069] The technical solution provided by the present invention sorts the multiple charging voltages obtained within the stack from largest to smallest, determines the operating range of the stack based on the relationship between the first n charging voltages and the preset voltage, and controls the charge and discharge control module to reduce the power or disconnect the stack, thereby preventing the overcharging risk of the first n batteries in the stack, extending the lifespan of the batteries in the stack, and improving the charging safety of the energy storage system.

[0070] Optionally, Figure 6 is a flowchart of another charge and discharge control method for an energy storage system provided by an embodiment of the present invention. Based on the above embodiment, refer to Figure 5 and Figure 6 . The preset voltage includes a first preset voltage U1 and a second preset voltage U2, and the first preset voltage U1 is greater than the second preset voltage U2.

[0071] The charge and discharge control method for this energy storage system includes:

[0072] S410. Obtain the charging voltage and discharging voltage of each battery in the stack.

[0073] S420. Sort the multiple charging voltages from largest to smallest.

[0074] S430. If the maximum value of the charging voltage is greater than or equal to the first preset voltage U1, determine that the stack is in the damaged range.

[0075] Specifically, as Figure 5As shown, when the charging voltage of the battery is greater than or equal to the first preset voltage U1, the battery is close to the fully charged state. If the battery is charged further, irreversible damage will be caused to the battery. The maximum value of the charging voltage can be the maximum value among all the sorted charging voltages. If the maximum value of the charging voltages of all the batteries in the stack is greater than or equal to the first preset voltage U1, it indicates that there is a battery in the stack close to the fully charged state, and it is determined that the stack is in the damage range.

[0076] S440. If the first n charging voltages are all greater than or equal to the second preset voltage and less than the first preset voltage, it is determined that the stack is in the high hydrogen production range.

[0077] Specifically, as Figure 5 shown, when the charging voltage of the battery is greater than or equal to the second preset voltage U2 and less than the first preset voltage U1, the battery will produce more hydrogen in this charging state. If multiple batteries in the stack are in the hydrogen production state, the hydrogen content in the stack will increase, which will bring safety risks. If the first n charging voltages of the batteries in the stack are all greater than or equal to the second preset voltage and less than the first preset voltage, it indicates that the n batteries in the stack are all in the hydrogen production state. Therefore, it is determined that the stack is in the high hydrogen production range. It should be noted that n can be determined according to the hydrogen content that the stack can accommodate and the hydrogen production amount of a single battery. Exemplarily, as Figure 1 shown in the energy storage system, the hydrogen content that the stack 200 can accommodate is 5, and the hydrogen produced by a single battery 300 in the stack 200 is 1. Then it can be determined that the stack 200 can accommodate at most five batteries 300 in the hydrogen production state at the same time, so the value of n is determined to be 5.

[0078] S450. Control the charge and discharge control module to reduce the power or cut off the stack according to the operating range of the stack.

[0079] The technical solution provided by the present invention determines whether the stack is in the damage range according to the relationship between the maximum value of the charging voltages of all the batteries in the stack and the first preset voltage, so as to accurately prevent the risk of overcharging the battery and extend the service life of the batteries in the stack; determine whether the stack is in the high hydrogen production range according to the relationship between the first n charging voltages and the first preset voltage and the second preset voltage, so as to avoid the flammable risk caused by excessive hydrogen production during the charging process of the batteries in the stack, and further improve the charging safety of the energy storage system.

[0080] Optionally, Figure 7 is a flowchart of another charge and discharge control method for an energy storage system provided by an embodiment of the present invention. On the basis of the above embodiment, see Figure 7 . The charge and discharge control method of this energy storage system includes:

[0081] S510. Obtain the charging voltage and discharging voltage of each battery in the stack.

[0082] S520. Sort multiple charging voltages from large to small.

[0083] S530. If the maximum value of the charging voltage is greater than or equal to the first preset voltage U1, it is determined that the stack is in the damaged range.

[0084] S540. If the stack is in the damaged range, control the charge-discharge control module to reduce the power.

[0085] Specifically, when it is first determined that the stack is in the damaged range, only a single battery in the stack is close to the fully charged state, and there is still a large charging margin for the remaining batteries in the stack. By controlling the charge-discharge control module to reduce the charging power of the corresponding stack, on the basis of ensuring that the batteries in the stack are not damaged, the remaining batteries in the stack can continue to be charged, so as to improve the utilization rate of the battery capacity in the stack and the charging efficiency of the energy storage system.

[0086] S550. Return to execute the steps of obtaining the charging voltage and discharging voltage of each battery in the stack, and execute them sequentially. If the stack is in the damaged range or the high hydrogen production range, the stack is cut off.

[0087] Specifically, after controlling the charge-discharge control module to reduce the power, it is possible to return to execute step S510, step S520, and step S530. Thus, the charging voltage of each battery in the stack after reducing the power is re-obtained, and the re-obtained charging voltages are sorted from large to small. Then, according to the relationship between the charging voltage re-obtained after reducing the power and the preset voltage, the operating range of the stack after reducing the power is further determined. If it is determined that the stack is in the damaged range or the high hydrogen production range after reducing the power, it means that the charging capacity of the stack has been exhausted. At this time, the stack can be cut off from this group of stacks without affecting the continuous charging of other stacks in the same group.

[0088] When it is first determined that the stack is in the damaged range, the technical solution provided by the present invention controls the charge-discharge control module to reduce the charging power of the corresponding stack until the stack is recharged to the damaged range or the high hydrogen production range before cutting off the stack. While ensuring that the battery is not overcharged, the other batteries in the stack with charging redundancy are fully utilized, which fully improves the utilization rate of the stack capacity; and when the charge-discharge control module controls a single stack to be cut off, it does not affect the charging of other stacks, thus improving the charge-discharge efficiency of the energy storage system.

[0089] Optionally, Figure 8 is a flowchart of another charge-discharge control method for an energy storage system provided by an embodiment of the present invention. On the basis of the above embodiment, refer to Figure 8 . This charge-discharge control method for an energy storage system includes:

[0090] S610. Obtain the charging voltage and discharging voltage of each cell in the stack.

[0091] S620. Sort multiple charging voltages from large to small.

[0092] S630. If the first n charging voltages are all greater than or equal to the second preset voltage and all less than the first preset voltage, then determine that the stack is in the high hydrogen production interval.

[0093] S640. If the stack is in the high hydrogen production interval, then control the charge-discharge control module to reduce the power.

[0094] Specifically, when it is first determined that the stack is in the high hydrogen production interval, multiple cells in the stack are in the hydrogen production state, and there is still a large charging margin for the remaining cells. However, the hydrogen content in the stack reaches the maximum limit, and continuing normal charging is likely to bring safety risks. By controlling the charge-discharge control module to reduce the charging power of the corresponding stack, on the basis of ensuring that the cells in the stack will not continue to produce hydrogen, the remaining cells in the stack can continue to be charged, so as to improve the utilization rate of the cell capacity in the stack and the charging efficiency of the energy storage system.

[0095] S650. Return to execute the step of obtaining the charging voltage and discharging voltage of each cell in the stack, and execute sequentially. If the stack is in the damage interval or the high hydrogen production interval, then cut off the stack.

[0096] Specifically, after controlling the charge-discharge control module to reduce the power, steps S610, S620, and S630 can be returned to execute. Thus, the charging voltage of each cell in the stack after reducing the power is re-obtained, and the re-obtained charging voltages are sorted from large to small. Then, according to the relationship between the charging voltage re-obtained after reducing the power and the preset voltage, the operating interval of the stack after reducing the power is further determined. If it is determined that the stack is in the damage interval or the high hydrogen production interval after reducing the power, it means that the charging capacity of the stack has been exhausted. At this time, the stack can be cut off from this group of stacks without affecting the charging of other stacks in the same group.

[0097] The technical solution provided by the present invention controls the charge-discharge control module to reduce the charging power of the corresponding stack when it is first determined that the stack is in the high hydrogen production interval, and cuts off the stack only when the stack is charged again to the damage interval or the high hydrogen production interval. While avoiding the safety risks brought by excessive hydrogen production during battery charging, the other cells in the stack with charging redundancy are fully utilized, and the utilization rate of the stack capacity is fully improved; and when the charge-discharge control module controls the excision of a single stack, it does not affect the charging of other stacks, thereby improving the charge-discharge efficiency of the energy storage system.

[0098] Optionally, Figure 9It is a flowchart of another charge and discharge control method for an energy storage system provided by an embodiment of the present invention. On the basis of the above embodiment, refer to Figure 5 and Figure 9 . The preset voltage further includes a third preset voltage U3. As Figure 5 shown, curve L2 is the curve of the discharge voltage of the battery changing with the power. In the discharge state, the discharge voltage of the battery gradually decreases as the battery power decreases. The charge and discharge control method of this energy storage system includes:

[0099] S710. Obtain the charging voltage and discharge voltage of each battery in the stack.

[0100] S720. Control the charge and discharge control module to reduce the power or cut off the stack according to the relationship between the minimum value of multiple discharge voltages and the third preset voltage.

[0101] Specifically, the lower the discharge voltage of the battery, the relatively less capacity the battery has for continued discharge. If the battery is over-discharged, it will affect the battery life and there are significant safety issues. The third preset voltage U3 can be a reference voltage value for judging whether the battery is over-discharged. Therefore, according to the relationship between the minimum value of the discharge voltage of each battery in the stack and the third preset voltage, it can be judged whether there is a battery over-discharged in the stack, and then the charge and discharge control module can be controlled to reduce the power or cut off the stack, so as to ensure the safe operation of the stack.

[0102] The technical solution provided by the present invention obtains the discharge voltage of each battery in the stack in the discharge state, judges the operating state of the stack during discharge according to the relationship between the discharge voltage and the third preset voltage, and thus controls the charge and discharge control module to reduce the power or cut off the stack in the discharge state, improving the charge and discharge efficiency of the stack.

[0103] Optionally, Figure 10 It is a flowchart of another charge and discharge control method for an energy storage system provided by an embodiment of the present invention. On the basis of the above embodiment, refer to Figure 10 . The charge and discharge control method of this energy storage system includes:

[0104] S810. Obtain the charging voltage and discharge voltage of each battery in the stack.

[0105] S820. If the minimum value of multiple discharge voltages is less than or equal to the third preset voltage, control the charge and discharge control module to reduce the power.

[0106] Specifically, when the minimum value among the discharge voltages of multiple cells in the stack is less than or equal to the third preset voltage, it indicates that one cell in the stack is in an over-discharge state. There is still a large discharge margin for the remaining cells in the stack. By controlling the charge-discharge control module to reduce the power of the corresponding stack during discharge, on the basis of ensuring that the cells in the stack are not damaged by over-discharge, the other cells in the stack that still have redundant power can continue to discharge, so as to improve the utilization rate of the cell capacity in the stack and the discharge efficiency of the energy storage system.

[0107] S830. Return to execute the step of obtaining the charging voltage and discharge voltage of multiple cells in the stack, and execute sequentially. If the minimum value among the multiple discharge voltages in the stack is still less than or equal to the third preset voltage, then cut off the stack.

[0108] Specifically, after controlling the charge-discharge control module to reduce the power, the discharge voltage of each cell in the stack after reducing the power can be obtained again, and according to the relationship between the discharge voltage after reducing the power and the third preset voltage, it can be further determined whether there is an over-discharged cell in the stack after reducing the power. If it is determined that there is an over-discharged cell in the stack after reducing the power, it means that the stored power in the stack has been exhausted. At this time, the stack can be cut off from this group of stacks without affecting the continuous discharge of other stacks in the same group.

[0109] The technical solution provided by the present invention obtains the discharge voltage of each cell in the stack in the discharge state, and determines whether there is an over-discharged cell in the stack during discharge according to the relationship between the discharge voltage and the third preset voltage. If there is an over-discharged cell, the charge-discharge control module is controlled to reduce the power. On the basis of avoiding over-discharge of the cell, other cells with redundant power continue to discharge until the stack is cut off when there is an over-discharged cell in the stack again, so as to extend the discharge time of the stack while ensuring the discharge safety of the stack and improve the discharge efficiency of the energy storage system.

[0110] Optionally, after cutting off the stack, the method further includes:

[0111] If the number of cut-off stacks in the same group is equal to the preset cut-off number, then stop the charge-discharge control.

[0112] Specifically, when multiple stacks in the same group of stacks are gradually cut off, the number of stacks put into use gradually decreases. To ensure the economic benefits of the energy storage system, it is necessary to ensure that a basic number of stacks are put into use. The preset cut-off number can be the minimum input amount of the stacks in the same group of the energy storage system. Exemplarily, as Figure 1 shown in the energy storage system, the number of stacks in the same group controlled by a charge-discharge control module 100 is 5, and at least one stack needs to be kept in use in this group, then the preset cut-off number is 4. After 4 stacks in this group of stacks are cut off, stop the charge-discharge control of this group of stacks.

[0113] When the number of stacks cut off in the same group in the technical solution provided by the present invention is equal to the preset cut-off number, the charge and discharge control is stopped, which improves the economic benefit of the energy storage system during charge and discharge.

[0114] An embodiment of the present invention also provides an energy storage system. The energy storage system provided by the embodiment of the present invention performs charge and discharge control by using the charge and discharge control method of the energy storage system provided in any of the above embodiments, and has the same beneficial effects as the charge and discharge control method of the energy storage system provided in any of the above embodiments, which will not be elaborated here.

[0115] It should be understood that various forms of the processes shown above can be used, steps can be reordered, added or deleted. For example, the steps described in the present invention can be executed in parallel, sequentially or in a different order, as long as the desired results of the technical solution of the present invention can be achieved, and no limitation is made herein.

[0116] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A charge and discharge control method for an energy storage system, characterized in that: The energy storage system includes multiple charge and discharge control modules and multiple groups of battery stacks, and the battery stacks include multiple batteries; each of the charge and discharge control modules is connected to a group of the battery stacks, and multiple battery stacks in the same group are connected in parallel; The charge and discharge control method of the energy storage system comprises: Obtaining charging and discharging voltages of multiple batteries in the battery stack; Determining an operating range of the battery stack according to a relationship between the charge and discharge voltage and a preset voltage; The charge and discharge control module is controlled to reduce power or cut off the battery stack according to the operation range of the battery stack.

2. The charge and discharge control method of the energy storage system according to claim 1, characterized in that: Obtaining the charge and discharge voltages of multiple batteries in the battery stack, including: The charging voltage and discharging voltage of each battery in the battery stack are obtained.

3. The charge and discharge control method of the energy storage system according to claim 2, characterized in that: Determining the operation range of the battery stack according to the relationship between the charge and discharge voltage and the preset voltage includes: sorting the plurality of charging voltages from large to small; The operating range of the battery stack is determined according to the relationship between the first n charging voltages and the preset voltage, where n is an integer greater than 0.

4. The charge and discharge control method of the energy storage system according to claim 3, characterized in that: The preset voltage includes a first preset voltage and a second preset voltage, and the first preset voltage is greater than the second preset voltage; Determining the operation range of the battery stack according to the relationship between the first n charging voltages and the preset voltage includes: If the maximum value of the charging voltage is greater than or equal to the first preset voltage, it is determined that the battery stack is in a damage range; If the first n charging voltages are all greater than or equal to the second preset voltage and are all less than the first preset voltage, it is determined that the fuel cell stack is in a high hydrogen production range.

5. The charge and discharge control method of the energy storage system according to claim 4, characterized in that: Controlling the charge and discharge control module to reduce power or cut off the battery stack according to the operation range of the battery stack includes: If the battery stack is in a damaged range, controlling the charge and discharge control module to reduce power; Return to the step of obtaining the charging voltage and discharging voltage of each battery in the battery stack, and execute them sequentially. If the battery stack is in the damaged interval or the high hydrogen production interval, cut off the battery stack.

6. The charge and discharge control method of the energy storage system according to claim 4, characterized in that: Controlling the charge and discharge control module to reduce power or cut off the battery stack according to the operation range of the battery stack includes: If the fuel cell stack is in a high hydrogen production range, controlling the charge and discharge control module to reduce power; Return to the step of obtaining the charging voltage and discharging voltage of each battery in the battery stack, and execute them sequentially. If the battery stack is in the damaged interval or the high hydrogen production interval, cut off the battery stack.

7. The charge and discharge control method of the energy storage system according to claim 2, characterized in that: The preset voltage also includes a third preset voltage, and after obtaining the charging voltage and the discharging voltage of each battery in the battery stack, the method further includes: The charge and discharge control module is controlled to reduce power or cut off the battery stack according to the relationship between the minimum value of the multiple discharge voltages and the third preset voltage.

8. The charge and discharge control method of the energy storage system according to claim 7, characterized in that: Controlling the charge and discharge control module to reduce power or cut off the battery stack according to the relationship between the minimum value of the plurality of discharge voltages and the third preset voltage includes: If the minimum value among the plurality of discharge voltages is less than or equal to the third preset voltage, controlling the charge and discharge control module to reduce power; Return to the step of obtaining the charge and discharge voltages of the multiple batteries in the battery stack, and execute them sequentially. If the minimum value of the multiple discharge voltages in the battery stack is still less than or equal to the third preset voltage, the battery stack is cut off.

9. The charge and discharge control method of the energy storage system according to claim 5, 6 or 8, characterized in that: After the battery stack is removed, the method further includes: If the number of cut-offs of the battery stacks in the same group is equal to the preset number of cut-offs, the charge and discharge control is stopped.

10. An energy storage system, characterized in that: The charging and discharging control method of the energy storage system according to any one of claims 1 to 9 is adopted to perform charging and discharging control.

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