Charging and discharging control method of multi-machine parallel energy storage system

Abstract

The invention relates to the technical field of charging and discharging of energy storage systems, and discloses a charging and discharging control method of a multi-machine parallel energy storage system, and the multi-machine parallel energy storage system comprises a plurality of energy storage devices which are connected in parallel. The method comprises the following steps: detecting the residual electric quantity of each energy storage device in the system, and calculating the residual electric quantity difference value of the multi-machine parallel energy storage system; comparing the residual electric quantity difference value with a set electric quantity difference value, if the residual electric quantity difference value is smaller than the set electric quantity difference value, executing a current distribution program, calculating and adjusting the charging current distributed to each energy storage device in the system, and if the residual electric quantity difference value is larger than or equal to the set electric quantity difference value, executing a current distribution program; and executing the residual electric quantity balancing program to reduce the residual electric quantity difference among the energy storage devices. The technical scheme provided by the invention aims to provide the charging and discharging control method for the multi-machine parallel energy storage system, which can prevent the residual electric quantity difference between the energy storage devices in the energy storage system from being too large.

Description

Technical Field

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

[0002] With the increasing demand for the capacitance of energy storage devices (batteries), the technology of parallel energy storage systems has been gradually applied to various energy storage systems. By paralleling multiple energy storage devices, the parallel energy storage system can significantly increase the overall capacitance of the energy storage system to meet greater power demands; and since the working states of each energy storage device are relatively independent, the operation of the entire energy storage system will not be affected when a certain energy storage device has problems. Therefore, the parallel energy storage system has good fault tolerance.

[0003] However, the parallel energy storage system also has some disadvantages. When multiple energy storage devices are used in parallel, due to factors such as manufacturing process differences, the internal resistances of the energy storage devices paralleled in the energy storage system will be different, resulting in differences in the charging current and discharging current of each battery. As the energy storage system continues to operate, there may be a problem that the remaining power differences between the energy storage devices in the energy storage system are too large, affecting the service life of the energy storage devices and the performance of the energy storage system.

[0004] Therefore, it is necessary to propose a charge and discharge control method for a multi-machine parallel energy storage system that can avoid the remaining power differences between the energy storage devices in the energy storage system from being too large. Summary of the Invention

[0005] The main object of the present invention is to provide a charge and discharge control method for a multi-machine parallel energy storage system that can avoid the remaining power differences between the energy storage devices in the energy storage system from being too large.

[0006] To achieve the above object, the present invention provides a charge and discharge control method for a multi-machine parallel energy storage system. The multi-machine parallel energy storage system includes a plurality of paralleled energy storage devices. The method includes the following steps:

[0007] Detect the remaining power of each energy storage device in the system and calculate the remaining power difference of the multi-machine parallel energy storage system;

[0008] Compare the remaining power difference with the set power difference;

[0009] If the remaining power difference is less than the set power difference, execute the current distribution program to calculate and adjust the charging current allocated to each energy storage device in the system;

[0010] If the remaining power difference is greater than or equal to the set power difference, execute the remaining power balancing program to reduce the remaining power differences between the energy storage devices.

[0011] Preferably, in the step of, if the remaining power difference is less than the set power difference, executing the current distribution program to calculate and adjust the charging current assigned to each energy storage device in the system, the calculation formula for calculating the charging current assigned to each energy storage device in the system is as follows:

[0012]

[0013] wherein, I i is the current assigned to the i-th energy storage device, R i is the current internal resistance of the i-th energy storage device, R j is the current internal resistance of the j-th energy storage device, N is the number of energy storage devices connected in parallel in the system, I total is the total current discharged by the multi-machine parallel energy storage system to the outside, SOC i is the remaining power of the i-th energy storage device, SOC j is the remaining power of the j-th energy storage device, SOC avg is the average value of the remaining power of the energy storage devices in the multi-machine parallel energy storage system, α represents the first weight, and β represents the second weight.

[0014] Preferably, in the step of, if the remaining power difference is greater than or equal to the set power difference, executing the remaining power balancing program to reduce the difference in the remaining power between the energy storage devices, the remaining power balancing program includes the following steps:

[0015] Increase the charging current of the energy storage device with a lower remaining power, decrease the charging current of the energy storage device with a higher remaining power, and preferentially select the energy storage device with a higher remaining power during discharging.

[0016] Preferably, in the step of detecting the remaining power of each energy storage device in the system and calculating the remaining power difference of the multi-machine parallel energy storage system, the remaining power difference is calculated according to the following formula:

[0017] ΔSOC = SOC max —SOC min ,

[0018] wherein, ΔSOC is the remaining power difference, SOC max is the remaining power corresponding to the energy storage device with the highest remaining power in the multi-machine parallel energy storage system during multi-machine parallel operation, SOC min is the remaining power corresponding to the energy storage device with the lowest remaining power in the multi-machine parallel energy storage system during multi-machine parallel operation.

[0019] In addition, to achieve the above object, the present invention also provides a multi-machine parallel energy storage system, which is characterized in that the charging and discharging control method of the multi-machine parallel energy storage system described in any one of the above is applied for charging and discharging control.

[0020] Preferably, the multi-machine parallel energy storage system includes a control module and multiple parallel energy storage devices. The control module is respectively connected to each energy storage device to monitor the voltage, current, remaining power, and internal resistance of each energy storage device in real time, and execute a current distribution program or a remaining power balancing program according to the difference in remaining power to adjust the charging current and discharging current of each energy storage device.

[0021] Preferably, the control module includes a main control unit and slave control units. The main control unit is respectively connected to each energy storage device to monitor the voltage, current, remaining power, and internal resistance of each energy storage device in real time. Each energy storage device is built-in with a slave control module, and each of the slave control units is communicatively connected to the main control unit. The main control unit is used to send a current distribution program or a remaining power balancing program to the slave control units according to the difference in remaining power. The slave control module is used to receive the current distribution program or the remaining power balancing program and dynamically adjust the charging current and discharging current of the energy storage device where it is located according to the current distribution program or the remaining power balancing program.

[0022] Preferably, the multi-machine parallel energy storage system is used to regularly measure the current internal resistance of each energy storage device and record the current internal resistance data obtained from each measurement, and calculate the aging degree of each energy storage device. The aging degree of the energy storage device is the ratio of the current internal resistance of the energy storage device to the initial internal resistance of the energy storage device.

[0023] Preferably, the calculation formula for the aging degree of the energy storage device is as follows:

[0024]

[0025] Where C 当前 is the current actual maximum capacitance of the energy storage device, C 初始 is the initial nominal capacitance of the energy storage device, and SOH 容量 is the aging degree of the energy storage device.

[0026] Preferably, the main control module is also used to calculate the current weight of each energy storage device according to the aging degree of each energy storage device, and calculate the current allocated to each energy storage device according to the current weight of the energy storage device, and adjust the distribution ratio of the charging current and discharging current of the energy storage device. The device with a higher weight is allocated more charging current and discharging current. The calculation formula for the current weight of the energy storage device is as follows:

[0027]

[0028] Where W i is the current weight of the i-th energy storage device, R i is the current internal resistance of the i-th energy storage device, R0 is the initial internal resistance of the i-th energy storage device, and C iis the current capacitance of the i-th energy storage device, C0 is the initial capacitance of the i-th energy storage device, T i is the temperature deviation ratio of the i-th energy storage device, ΔSOC i is the SOC offset of the i-th energy storage device, α1 is the weight coefficient of the temperature deviation ratio, and β1 is the weight coefficient of the SOC offset;

[0029] The calculation formula for calculating the current allocated to each energy storage device according to the current weight of the energy storage device is as follows:

[0030]

[0031] where, I i is the current allocated to the i-th energy storage device, N is the number of energy storage devices connected in parallel in the system, I total is the total current discharged by the multi-machine parallel energy storage system to the outside, W j is the current weight of the j-th energy storage device.

[0032] Preferably, the main control unit is used to suspend charging the energy storage device whose voltage has risen to the charging upper limit of the energy storage device when the voltage of the energy storage device rises to the charging upper limit; the main control unit is also used to control the energy storage device whose voltage has dropped to the discharge lower limit to suspend discharging when the voltage of the energy storage device drops to the discharge lower limit.

[0033] In the technical solution of the present invention, by detecting the remaining power of each energy storage device in the system and calculating the remaining power difference of the multi-machine parallel energy storage system, when the remaining power difference is greater than or equal to the set power difference, the remaining power equalization program is executed to reduce the remaining power difference between each energy storage device, and to avoid too large a difference in the remaining power between each energy storage device in the energy storage system; in addition, when the remaining power difference is less than the set power difference, the current distribution program is executed to make the current of each energy storage device evenly distributed, and to avoid overload or idle phenomena. Description of the Drawings

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention, and for those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0035] Figure 1 is the flowchart of the charge and discharge control method of the multi-machine parallel energy storage system of the present invention.

[0036] The realization of the object, functional characteristics and advantages of the present invention will be further described in conjunction with the embodiments with reference to the drawings. Detailed implementation manners

[0037] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with 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 making creative efforts fall within the protection scope of the present invention.

[0038] It should be noted that all the directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0039] In addition, the descriptions such as "first" and "second" in the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0040] In the present invention, unless otherwise clearly defined and limited, the terms "connected", "fixed", etc. should be understood in a broad sense. For example, "fixed" may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal connection of two components or the interaction relationship between two components, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0041] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0042] Please refer to Figure 1 , to achieve the above object, the charge and discharge control method of the multi-machine parallel energy storage system proposed by the present invention, the multi-machine parallel energy storage system includes a plurality of parallel energy storage devices, and the method includes the following steps:

[0043] Step S1: Detect the remaining power of each energy storage device in the system and calculate the remaining power difference of the multi-machine parallel energy storage system;

[0044] Step S2: Compare the remaining power difference with the set power difference;

[0045] Step S3: If the remaining power difference is less than the set power difference, execute the current distribution program to calculate and adjust the charging current allocated to each energy storage device in the system;

[0046] Step S4: If the remaining power difference is greater than or equal to the set power difference, execute the remaining power balancing program to reduce the difference in remaining power between each energy storage device. The current distribution program directly changes the change rate of the remaining power of the device by adjusting the current distribution ratio, and the remaining power balancing program affects the current demand of the energy storage device, thereby indirectly changing the implementation effect of the current distribution program; in this embodiment, the set power difference is 5%.

[0047] In the technical solution of the present invention, by detecting the remaining power of each energy storage device in the system and calculating the remaining power difference of the multi-machine parallel energy storage system, when the remaining power difference is greater than or equal to the set power difference, execute the remaining power balancing program to reduce the difference in remaining power between each energy storage device in the energy storage system, and avoid too large a difference in remaining power between each energy storage device in the energy storage system; in addition, when the remaining power difference is less than the set power difference, execute the current distribution program to make the current of each energy storage device evenly distributed, and avoid overload or idle phenomena.

[0048] Preferably, in the step S3, the calculation formula for calculating the charging current allocated to each energy storage device in the system is:

[0049]

[0050] where, I i is the current allocated to the i-th energy storage device, R i is the current internal resistance of the i-th energy storage device, R j is the current internal resistance of the j-th energy storage device, N is the number of energy storage devices connected in parallel in the system, I total is the total current discharged by the multi-machine parallel energy storage system to the outside, SOC i is the remaining power of the i-th energy storage device, SOC j is the remaining power of the j-th energy storage device, SOC avg is the average value of the remaining power of the energy storage devices in the multi-machine parallel energy storage system, α represents the first weight, and β represents the second weight. In this embodiment, both α and β are 50%.

[0051] Preferably, in the step S4, the remaining power balancing program includes the following steps:

[0052] Increase the charging current of the energy storage device with lower remaining power, decrease the charging current of the energy storage device with higher remaining power, and preferentially select the energy storage device with higher remaining power during discharging.

[0053] Preferably, in the step S1, the remaining power difference is calculated according to the following formula:

[0054] ΔSOC = SOC max — SOC min ,

[0055] where ΔSOC is the remaining power difference, SOC max is the remaining power of the energy storage device with the highest remaining power in the multi - machine parallel energy storage system during multi - machine parallel operation, and SOC min is the remaining power of the energy storage device with the lowest remaining power in the multi - machine parallel energy storage system during multi - machine parallel operation. The remaining power (State Of Charge, abbreviated as SOC) is the ratio of the available power in the battery to the nominal capacity, usually in percentage.

[0056] In addition, to achieve the above object, the present invention also proposes a multi - machine parallel energy storage system, which performs charge - discharge control by applying the charge - discharge control method of the multi - machine parallel energy storage system described in any one of the above. The multi - machine parallel energy storage system includes a control module and a plurality of parallel energy storage devices. The control module is respectively connected to each energy storage device to monitor the voltage, current, remaining power, and internal resistance of each energy storage device in real time, and execute a current distribution program or a remaining power balancing program according to the remaining power difference to adjust the charging current and discharging current of each energy storage device. Through the control module, the operating state of each energy storage device is monitored in real time, and a current distribution program or a remaining power balancing program is executed according to the remaining power difference to adjust the charging current and discharging current of each energy storage device, realizing the dynamic balance of the charging and discharging currents of each energy storage device in the energy storage system, solving the problem of uneven distribution of charging and discharging currents caused by internal resistance differences of each energy storage device, and avoiding overloading or failure of the energy storage device.

[0057] Preferably, the control module includes a main control unit and a slave control unit. The main control unit is respectively connected to each energy storage device to monitor the voltage, current, remaining power, and internal resistance of each energy storage device in real time. Each energy storage device is internally provided with a slave control module, and each of the slave control units is communicatively connected to the main control unit. The main control unit is used to send a current distribution program or a remaining power balancing program to the slave control unit according to the remaining power difference, and the slave control module is used to receive the current distribution program or the remaining power balancing program and dynamically adjust the charging current and discharging current of the energy storage device where it is located. In this embodiment, SOC max and SOC minAll are obtained through the master control module unit. Each slave control unit is communicatively connected to the master control unit via a CAN bus, RS485, or wireless communication, thereby realizing efficient data exchange between the master control unit and the slave control units and ensuring synchronous transmission of the charge and discharge distribution instructions.

[0058] Specifically, the multi-machine parallel energy storage system further includes a current distribution module. The current distribution module is respectively connected to the master control unit and the energy storage converter of the energy storage system, and is used to control the energy storage converter of the energy storage system to charge each energy storage device according to the current distribution ratio calculated by the master control unit.

[0059] Preferably, the multi-machine parallel energy storage system is used to regularly measure the current internal resistance of each energy storage device and record the current internal resistance data obtained from each measurement, and calculate the aging degree of each energy storage device. The aging degree of the energy storage device is the ratio of the current internal resistance of the energy storage device to the initial internal resistance of the energy storage device. The system measures the current internal resistance of the energy storage device when the energy storage device is in a specific state (such as when the energy storage device is fully charged or when the energy storage device discharges to its own discharge lower limit).

[0060] Preferably, the calculation formula for the aging degree of the energy storage device is as follows:

[0061]

[0062] Where C 当前 is the current actual maximum capacitance of the energy storage device, C 初始 is the initial nominal capacitance of the energy storage device, and SOH 容量 is the aging degree of the energy storage device. C 初始 is usually obtained by performing a full charge and discharge test on the energy storage device. Generally, the test is carried out and marked when the energy storage device leaves the factory, which can reflect the electricity storage performance of the initial state of the energy storage device. The capacitance of the energy storage device will decrease with the charge and discharge cycles and aging of the energy storage device. C 当前 can reflect the current electricity storage performance of the energy storage device, and SOH 容量 is an important indicator to measure the health of the battery or energy storage device.

[0063] Specifically, the master control module is further used to reduce the workload of the energy storage device with a higher aging degree, preferentially allocate the charge and discharge tasks to the energy storage device with a lower aging degree, and limit the maximum charge current and maximum discharge current of the energy storage device with a higher aging degree, so as to avoid further damage to the energy storage device with a higher aging degree caused by excessive charge current and discharge current, thereby prolonging the overall life of the system.

[0064] Preferably, the main control module is further configured to calculate the current weight of each energy storage device according to the aging degree of each energy storage device, calculate the current allocated to each energy storage device according to the current weight of the energy storage device, adjust the distribution ratio of the charging current and the discharging current of the energy storage device, and allocate more charging current and discharging current to the device with a higher weight. The calculation formula for the current weight of the energy storage device is as follows:

[0065]

[0066] Wherein, W i is the current weight of the i-th energy storage device, R i is the current internal resistance of the i-th energy storage device, R0 is the initial internal resistance of the i-th energy storage device, C i is the current capacitance of the i-th energy storage device, C0 is the initial capacitance of the i-th energy storage device, T i is the temperature deviation ratio of the i-th energy storage device, ΔSOC i is the SOC offset of the i-th energy storage device, α1 is the weight coefficient of the temperature deviation ratio, and β1 is the weight coefficient of the SOC offset;

[0067] The calculation formula for calculating the current allocated to each energy storage device according to the current weight of the energy storage device is as follows:

[0068]

[0069] Wherein, I i is the current allocated to the i-th energy storage device, N is the number of energy storage devices connected in parallel in the system, I total is the total current discharged by the multi-machine parallel energy storage system to the outside, and W j is the current weight of the j-th energy storage device.

[0070] Preferably, the main control unit is configured to suspend charging the energy storage device whose voltage has risen to the charging upper limit of the energy storage device; the main control unit is further configured to control the energy storage device whose voltage has dropped to the discharging lower limit to suspend discharging when the voltage of the energy storage device drops to the discharging lower limit. When the voltage of a certain energy storage device rises to the charging upper limit of the energy storage device, charging of the energy storage device is suspended. When the voltage of a certain energy storage device drops to the discharging lower limit, the energy storage device is controlled to suspend discharging, which can reduce the aging of the energy storage device caused by overcharging and over-discharging and extend the overall life of the multi-machine parallel energy storage system.

[0071] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made under the concept of the present invention by using the content of the specification and drawings of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A charge and discharge control method for a multi-machine parallel energy storage system, characterized in that, The multi-machine parallel energy storage system includes multiple parallel energy storage devices, and the method includes the following steps: Detect the remaining power of each energy storage device in the system and calculate the remaining power difference of the multi-machine parallel energy storage system; Compare the remaining power difference with the set power difference; If the remaining power difference is less than the set power difference, execute the current distribution program to calculate and adjust the charging current allocated to each energy storage device in the system; If the remaining power difference is greater than or equal to the set power difference, execute the remaining power balancing program to reduce the remaining power difference between each energy storage device.

2. The charge and discharge control method of the multi-machine parallel energy storage system according to claim 1, wherein In the step of "if the remaining power difference is less than the set power difference, execute the current distribution program to calculate and adjust the charging current allocated to each energy storage device in the system", the calculation formula for calculating the charging current allocated to each energy storage device in the system is: Among them, I i is the current allocated to the i-th energy storage device, R i is the current internal resistance of the i-th energy storage device, R j is the current internal resistance of the j-th energy storage device, N is the number of energy storage devices connected in parallel in the system, I total is the total current of the multi-machine parallel energy storage system discharging to the outside, SOC i is the remaining power of the i-th energy storage device, SOC j is the remaining power of the j-th energy storage device, SOC avg is the average value of the remaining power of the energy storage devices in the multi-machine parallel energy storage system. α represents the first weight, and β represents the second weight.

3. The charge and discharge control method of the multi-machine parallel energy storage system according to claim 1, wherein In the step of "if the remaining power difference is greater than or equal to the set power difference, execute the remaining power balancing program to reduce the remaining power difference between each energy storage device", the remaining power balancing program includes the following steps: Increase the charging current of the energy storage device with a lower remaining power, decrease the charging current of the energy storage device with a higher remaining power, and preferentially select the energy storage device with a higher remaining power during discharging.

4. The charge and discharge control method of the multi-machine parallel energy storage system according to claim 1, wherein In the step of "detect the remaining power of each energy storage device in the system and calculate the remaining power difference of the multi-machine parallel energy storage system", the remaining power difference is calculated according to the following formula: ΔSOC = SOC max — SOC min , Among them, ΔSOC is the difference in remaining battery capacity, and SOC max is the remaining battery capacity corresponding to the energy storage device with the highest remaining battery capacity in the multi-machine parallel energy storage system during multi-machine parallel operation, and SOC min is the remaining battery capacity corresponding to the energy storage device with the lowest remaining battery capacity in the multi-machine parallel energy storage system during multi-machine parallel operation.

5. A multi-machine parallel energy storage system, characterized in that, Use the charge and discharge control method of the multi-machine parallel energy storage system described in any one of claims 1-4 for charge and discharge control. The multi-machine parallel energy storage system includes a control module and multiple parallel energy storage devices. The control module is respectively connected to each energy storage device to monitor the voltage, current, remaining power and internal resistance of each energy storage device in real time, and execute the current distribution program or the remaining power balancing program according to the remaining power difference to adjust the charging current and discharging current of each energy storage device.

6. The multi-machine parallel energy storage system according to claim 5, wherein The control module includes a main control unit and a slave control unit. The main control unit is respectively connected to each energy storage device to monitor the voltage, current, remaining power and internal resistance of each energy storage device in real time. A slave control module is built in each energy storage device, and each slave control unit is communicatively connected to the main control unit. The main control unit is used to send the current distribution program or the remaining power balancing program to the slave control unit according to the remaining power difference. The slave control module is used to receive the current distribution program or the remaining power balancing program and dynamically adjust the charging current and discharging current of the energy storage device where it is located according to the current distribution program or the remaining power balancing program.

7. The multi-machine parallel energy storage system according to claim 6, wherein The multi-machine parallel energy storage system is used to regularly measure the current internal resistance of each energy storage device and record the current internal resistance data obtained from each measurement, and calculate the aging degree of each energy storage device. The aging degree of the energy storage device is the ratio of the current internal resistance of the energy storage device to the initial internal resistance of the energy storage device.

8. The multi-machine parallel energy storage system according to claim 6, characterized in that, The calculation formula for the aging degree of the energy storage device is as follows: Among them, C 当前 is the current actual maximum capacitance of the energy storage device, and C 初始 is the initial nominal capacitance of the energy storage device, and SOH 容量 is the aging degree of the energy storage device.

9. The multi-machine parallel energy storage system according to claim 8, wherein The master control module is also used to calculate the current weights of the energy storage devices according to the aging degree of each energy storage device, calculate the current allocated to each energy storage device according to the current weights of the energy storage devices, adjust the distribution ratio of the charging current and the discharging current of the energy storage devices, and allocate more charging current and discharging current to the device with a higher weight; The calculation formula for the current weight of the energy storage device is as follows: Among them, W i is the current weight of the i-th energy storage device, R i is the current internal resistance of the i-th energy storage device, R0 is the initial internal resistance of the i-th energy storage device, C i is the current capacitance of the i-th energy storage device, C0 is the initial capacitance of the i-th energy storage device, T i is the temperature deviation ratio of the i-th energy storage device, ΔSOC i is the SOC offset of the i-th energy storage device, α1 is the weight coefficient of the temperature deviation ratio, and β1 is the weight coefficient of the SOC offset; The calculation formula for calculating the current allocated to each energy storage device according to the current weight of the energy storage device is as follows: Among them, I i is the current allocated to the i-th energy storage device, N is the number of energy storage devices connected in parallel in the system, and I total is the total current discharged by the multi-machine parallel energy storage system to the outside, and W j is the current weight of the j-th energy storage device.

10. The multi-machine parallel energy storage system according to claim 6, characterized in that, The master control unit is used to suspend charging the energy storage device whose voltage has risen to the charging upper limit of the energy storage device when the voltage of the energy storage device rises to the charging upper limit; the master control unit is also used to control the energy storage device whose voltage has dropped to the discharging lower limit to suspend discharging when the voltage of the energy storage device drops to the discharging lower limit.

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