Flow battery energy storage balancing system and method

Abstract

The invention discloses a flow battery energy storage balancing system, and belongs to the technical field of electrochemical energy storage. The flow battery energy storage balancing system comprises a main system used for providing power supply voltage and energy storage capacity, the main system is connected with a balancing system used for balancing the capacity and the voltage of the main system, and the flow battery energy storage balancing system further comprises an electrical control system connected with the main system and the balancing system. The invention also discloses a flow battery energy storage balancing method. The energy storage balancing system of the flow battery is suitable for engineering application, is simple and convenient to operate, and can actively balance the inconsistency of charge states among multiple sets of process systems of the flow battery and reduce the difference among the systems, so that the utilization rate of the electrolyte is improved, the system efficiency is improved, and long-term operation of the battery and efficient utilization of the electrolyte can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical energy storage, and in particular to a liquid flow battery energy storage equalization system and method. Background Art

[0002] Renewable energy sources such as solar energy and wind energy are random and intermittent. To ensure stable power output, energy storage technology is needed. Liquid flow batteries are a new type of large-capacity energy storage battery that is currently developing rapidly. Compared with lead-acid batteries and nickel-hydrogen batteries, they have the advantages of large capacity, support for frequent high-current charging and discharging, strong scalability, and long life.

[0003] In large-scale energy storage systems, in order to provide higher power supply voltage and energy storage capacity, it is necessary to connect multiple single cell stacks in series and parallel to form a liquid flow battery group, and configure corresponding storage tanks for a certain number of liquid flow battery groups, modularizing them into container products of certain specifications. The differences in flow resistance, internal resistance, etc. caused by differences in internal materials and structures of single cell stacks will eventually lead to inconsistent stack voltages during charging and discharging, resulting in overcharging or over-discharging of the battery. In a series battery pack, in order to prevent the battery from overcharging, when one reaches the cut-off voltage, other stacks on the branch are also forced to stop, resulting in different electrolyte charging and discharging depths between different containers, and reducing the overall electrolyte utilization rate. In order to ensure the long-term and more efficient operation of the liquid flow battery, it is necessary to add a balancing control strategy to achieve voltage and capacity balance between multiple process systems.

[0004] At present, a widely used balancing method in lithium batteries and lead-acid batteries is the Fit Capacitor Method, a type of energy transfer balancing circuit. The energy transfer balancing method is one of the two major balancing strategies proposed by experts and scholars. It transfers energy from energy storage units with higher terminal voltages to energy storage units with lower terminal voltages through inductors, capacitors and DC converters. The other type is the energy consumption balancing method, which achieves balancing by connecting shunt elements in parallel to unit batteries and consuming high-capacity monomer energy. However, this method will reduce system efficiency, so it is not suitable for enlarged application in actual engineering.

[0005] Due to the characteristics of the flow battery process, the strategy can be studied and implemented from the perspective of balancing circuits, and the balancing process can also be studied and applied from the perspective of process design. At present, for the balancing control strategies of large-capacity energy storage systems such as all-vanadium and zinc-iron flow batteries with simple process pipelines, most of them are simulated and researched from the circuit aspect, but there is no research and design related to the balancing process of flow batteries, especially for iron-chromium flow batteries.

[0006] Therefore, researching and designing a process suitable for active balancing between multiple process systems for flow battery energy storage systems is one of the focuses of researchers in this field. Summary of the invention

[0007] The object of the present invention is to provide a liquid flow battery energy storage balancing system and method, which are used to solve the technical problem of voltage and capacity imbalance in the liquid flow battery energy storage system in the prior art.

[0008] To achieve the above-mentioned purpose, an embodiment of the present invention provides a liquid flow battery energy storage balancing system, including a main system for providing power supply voltage and energy storage capacity, the main system is connected to a balancing system for balancing the capacity and voltage of the main system, and the liquid flow battery energy storage balancing system also includes an electrical control system connected to the main system and the balancing system.

[0009] One of the preferred solutions of the present invention is that the main system includes at least two subsystems, each subsystem includes a SOC meter, at least two subsystem electrolyte storage tanks and at least one subsystem battery stack, the SOC meter is connected to the subsystem electrolyte storage tank and the subsystem battery stack, and a subsystem circulation pump is arranged between each subsystem electrolyte storage tank and the subsystem battery stack.

[0010] In one of the preferred solutions of the present invention, the balancing system includes at least one balancing stack, the balancing stack is connected to a balancing control component and a balancing electrolyte storage tank, and a balancing circulation pump is provided between the balancing electrolyte storage tank and the balancing stack.

[0011] In one of the preferred solutions of the present invention, the balancing system further includes a balancing communication pipeline, and the main system and the balancing system are connected through the balancing communication pipeline.

[0012] In one of the preferred solutions of the present invention, the balancing control component includes a regulating valve, the subsystem is connected to the balancing stack through two pipelines, and the regulating valve is arranged on the two pipelines.

[0013] In one of the preferred solutions of the present invention, the electrical control system is connected to the balancing stack, the SOC measuring device and the balancing control component.

[0014] Based on a liquid flow battery energy storage balancing system disclosed in the present invention, the present invention also discloses a liquid flow battery energy storage balancing method, which is implemented based on the above-mentioned liquid flow battery energy storage balancing system, including the following steps:

[0015] The electrical control system obtains the SOC value of each subsystem in the main system, and adjusts the electrolyte flow of the main system through the balancing system according to the obtained SOC value, thereby achieving balance of the capacity and voltage of the main system.

[0016] One of the preferred solutions of the present invention comprises the following steps:

[0017] Determine the composition of the main system and the balancing system in the flow battery energy storage balancing system;

[0018] The electrical control system obtains the SOC value of each subsystem in the main system;

[0019] The electrical control system adjusts the flow of the electrolyte storage tank according to the obtained SOC value;

[0020] The electrical control system adjusts the flow of the subsystem electrolyte storage tank in the subsystem according to the acquired SOC value.

[0021] One of the preferred solutions of the present invention is to determine the composition of the main system and the balancing system in the liquid flow battery energy storage balancing system, including: determining the number of subsystems in the main system and the number of subsystem stacks in the subsystem according to demand.

[0022] In one of the preferred solutions of the present invention, the electrical control system obtains the SOC value of each subsystem in the main system, including: the electrical control system obtains the SOC value of each subsystem through a SOC measuring device provided in the subsystem.

[0023] One of the preferred schemes of the present invention is that the electrical control system adjusts the flow of the balancing electrolyte storage tank according to the obtained SOC value, including: the electrical control system controls the balancing circulation pump to pump the solution in the balancing electrolyte storage tank into the balancing cell stack, and the pumping amount of the balancing circulation pump is the total flow of the main system flowing through the balancing cell stack.

[0024] One of the preferred schemes of the present invention is that the electrical control system adjusts the flow of the subsystem electrolyte storage tank in the subsystem according to the acquired SOC value, including: when the electrical control system determines that the SOC charge state of each subsystem in the main system differs by 1%, the regulating valve and the balancing connecting pipeline are opened to adjust the flow of the subsystem electrolyte storage tank to make the SOC charge state of each subsystem consistent.

[0025] One of the preferred schemes of the present invention is that the electrical control system adjusts the flow of the subsystem electrolyte storage tank in the subsystem according to the acquired SOC value, including: when the electrical control system determines that the SOC charge state of each subsystem in the main system is consistent and the overpotential is inconsistent, the SOC charge state of each subsystem is adjusted to make the charging and discharging voltages of each subsystem consistent.

[0026] One of the preferred solutions of the present invention is that the electrical control system adjusts the flow rate of the subsystem electrolyte storage tank in the subsystem according to the acquired SOC value, including: when the electrical control system determines that the SOC charge state of each subsystem in the main system differs from the initial state by 1%, the liquid flow battery energy storage balancing system is regulated by the regulating valve to perform charging recovery, and after the charging recovery is completed, the charge state balancing and voltage balancing control procedures between the subsystems are performed.

[0027] In summary, the beneficial effects of the present invention are:

[0028] 1. The liquid flow battery energy storage balancing method of the present invention obtains and analyzes the SOC (state of charge, also known as remaining power) charge value of each subsystem in the main system through an electrical control system, and adjusts the balancing system according to the obtained SOC charge value, so that the liquid flow battery energy storage balancing system is automatically charged continuously or intermittently, thereby balancing or restoring the SOC charge state of each subsystem in the main system, thereby improving the electrolyte utilization rate and system efficiency, extending the battery life, and ensuring the battery performance.

[0029] 2. The liquid flow battery energy storage balancing system of the present invention is suitable for engineering applications, is easy to operate, and can actively balance and restore the charge state of multiple subsystems of the liquid flow battery energy storage system, thereby improving the differences between systems, thereby improving the problem of low electrolyte utilization caused by the differences between systems, further improving system efficiency, reducing system costs, and achieving long-term operation of the battery and efficient use of the electrolyte.

[0030] 3. The liquid flow battery energy storage balancing system and method of the present invention are generally applicable to aqueous liquid flow batteries (supporting electrolytes are neutral or acidic, such as sulfuric acid, hydrochloric acid, mixed acid systems, etc.), and are applicable to liquid flow battery energy storage systems and projects of various sizes, so as to achieve high electrolyte utilization, high storage capacity, high performance (voltage efficiency, stack efficiency, system efficiency, etc.), high number of cycles, and long service life with stable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of the liquid flow battery energy storage equalization system of the present invention;

[0032] Figure 2 It is a flow chart of the energy storage balancing method of a liquid flow battery of the present invention;

[0033] Figure 3 This is a diagram showing the SOC state of charge of two subsystems with cycles with and without the addition of a balancing system in Example 1 of the present invention;

[0034] Figure 4 This is a diagram showing the variation of discharge capacity of two subsystems with cycles with adding a balancing system and without adding a balancing system in Example 1 of the present invention.

[0035] Among them, 1-subsystem fuel cell stack, 2-regulating valve, 3-SOC meter, 4-electrical control system, 5-subsystem circulation pump, 6-subsystem electrolyte storage tank, 7-balancing circulation pump, 8-balancing electrolyte storage tank, 9-balancing fuel cell stack. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0037] The present invention provides a liquid flow battery energy storage balancing system, such as Figure 1 As shown, it includes a main system for providing power supply voltage and energy storage capacity, the main system is connected to a balancing system for balancing the capacity and voltage of the main system, and the liquid flow battery energy storage balancing system also includes an electrical control system 4 connected to the main system and the balancing system, and the electrical control system 4 controls the operation of the entire liquid flow battery energy storage balancing system.

[0038] The main system includes at least two subsystems, the number of which depends on demand, and the subsystems are connected in series. This arrangement has the advantages of improving electrolyte utilization, improving battery pack performance, and improving system performance, thereby having the characteristics of reducing costs, simplifying operations, and quantitative control. Each subsystem includes an SOC measurer 3, at least two subsystem electrolyte storage tanks 6, and at least one subsystem stack 1. The SOC measurer 3 is connected to the subsystem electrolyte storage tank 6 and the subsystem stack 1 through a pipeline. A subsystem circulation pump 5 is provided between each subsystem electrolyte storage tank 6 and the subsystem stack 1, and the solution in the subsystem electrolyte storage tank 6 is pumped into the subsystem stack 1 through the subsystem circulation pump 5. The subsystem electrolyte storage tank 6 is a subsystem positive electrode electrolyte storage tank or a subsystem negative electrode electrolyte storage tank. When one of the subsystem electrolyte storage tanks 6 is a subsystem positive electrode electrolyte storage tank, the other subsystem electrolyte storage tank 6 is a subsystem negative electrode electrolyte storage tank. A subsystem includes a subsystem positive electrode electrolyte storage tank, a subsystem negative electrode electrolyte storage tank, at least one subsystem battery stack 1 and a SOC measurer 3, wherein the number of subsystem battery stacks 1 depends on demand. When the number of subsystem battery stacks 1 is greater than or equal to 2, the subsystem battery stacks 1 are connected in parallel.

[0039] The balancing system includes at least one balancing stack 9, which is connected to a balancing control component and a balancing electrolyte storage tank 8 through pipelines, and a balancing circulation pump 7 is arranged between the balancing electrolyte storage tank 8 and the balancing stack 9, and the solution in the balancing electrolyte storage tank 8 is pumped into the balancing stack 9 through the balancing circulation pump 7. The balancing control component includes a regulating valve 2, and the subsystem is connected to the balancing stack 9 through two pipelines, and the regulating valve 2 is arranged on the two pipelines.

[0040] The balancing system also includes a balancing interconnecting pipeline. The main system and the balancing system are connected through the balancing interconnecting pipeline, that is, the subsystem is also connected to the balancing system through the balancing interconnecting pipeline, and the subsystems are also connected through the balancing interconnecting pipeline. The subsystem and the balancing system also include corresponding measuring instruments and pipeline fittings.

[0041] The electrical control system 4 is connected to the balancing stack 9, the SOC measuring device 3 and the balancing control component through pipelines. The electrical control system 4 reads and analyzes the values ​​displayed by the SOC measuring device 3 in each subsystem, and adjusts the regulating valve 2 in the balancing control component according to the obtained values, and then adjusts the flow of the subsystem electrolyte storage tank 6 in each subsystem, thereby adjusting the SOC charge state of each subsystem to keep the SOC charge state of each subsystem consistent; at the same time, the electrical control system 4 also controls the balancing circulation pump 7 to pump the solution in the balancing electrolyte storage tank 8 into the balancing stack 9 according to the values ​​displayed by the SOC measuring device 3 in each subsystem, and the pumping amount of the balancing circulation pump 7 is the total flow of the solution in the subsystem electrolyte storage tank 6 in each subsystem in the main system flowing through the balancing stack 9.

[0042] Working process: The electrolyte storage tanks 6 of one subsystem in each subsystem of the main system are combined to form a positive electrolyte storage tank or a negative electrolyte storage tank in the liquid flow battery energy storage balancing system, and the balancing electrolyte storage tank 8 in the balancing system serves as another positive electrolyte storage tank or a negative electrolyte storage tank in the liquid flow battery energy storage balancing system. The polarities of the two electrolyte storage tanks in the liquid flow battery energy storage balancing system are opposite; the electrical control system 4 reads and analyzes the values ​​displayed by the SOC measuring devices 3 in each subsystem, and adjusts the regulating valve 2 in the balancing control component according to the obtained values, thereby adjusting the flow of each subsystem and the balancing electrolyte storage tank 8, so that the liquid flow battery energy storage balancing system is automatically charged continuously or intermittently, thereby balancing the SOC charge state of each subsystem.

[0043] A flow battery energy storage balancing method is implemented based on the above-mentioned flow battery energy storage balancing system, comprising the following steps: the electrical control system 4 obtains the SOC value of each subsystem in the main system, and adjusts the electrolyte flow of the main system through the balancing system according to the obtained SOC value, so as to achieve the balance of the capacity and voltage of the main system; specifically, Figure 2 As shown, the following steps are included:

[0044] Step (1): determine the composition of the main system and the balancing system in the liquid flow battery energy storage balancing system; specifically: determine the number of subsystems in the main system and the number of subsystem battery stacks 1 in the subsystem according to the needs, and also determine whether the subsystem electrolyte storage tank 6 is a positive electrode electrolyte storage tank or a negative electrode electrolyte storage tank in the subsystem, and determine the polarity of the balancing electrolyte storage tank 8 according to the polarity of the subsystem electrolyte storage tank 6, that is, when the subsystem electrolyte storage tank 6 is a positive electrode electrolyte storage tank, the balancing electrolyte storage tank 8 is a negative electrode electrolyte storage tank, and when the subsystem electrolyte storage tank 6 is a negative electrode electrolyte storage tank, the balancing electrolyte storage tank 8 is a positive electrode electrolyte storage tank;

[0045] Step (2): the electrical control system 4 obtains the SOC value of each subsystem in the main system; specifically: the electrical control system 4 obtains the SOC value of each subsystem through the SOC measuring device 3 set in the subsystem;

[0046] Step (3): the electrical control system 4 adjusts the flow of the balancing electrolyte storage tank 8 according to the acquired SOC value; specifically: the electrical control system 4 controls the balancing circulation pump 7 to pump the solution in the balancing electrolyte storage tank 8 into the balancing cell stack 9, and the pumping amount of the balancing circulation pump 7 is the total flow of each subsystem in the main system flowing through the balancing cell stack 9;

[0047] Step (4): the electrical control system 4 adjusts the flow rate of the subsystem electrolyte storage tank 6 in the subsystem according to the acquired SOC value; specifically, the following three situations are included:

[0048] ① When the electrical control system 4 determines that the SOC charge state of each subsystem in the main system differs by 1%, the regulating valve 2 and the balancing connecting pipeline are opened to adjust the flow of the subsystem electrolyte storage tank 6 to make the SOC charge state of each subsystem consistent;

[0049] ② When the electrical control system 4 determines that the SOC charge states of the subsystems in the main system are consistent, but the overpotentials of the subsystems are inconsistent due to differences in the battery stack, materials, pipelines, temperature, etc., resulting in inconsistent charge and discharge cut-off voltages of the subsystems, the SOC charge state of each subsystem is adjusted to match the overpotential of each system, so that the final charge and discharge voltages of multiple groups of subsystems are consistent, thereby improving the utilization rate of the electrolyte, improving the performance of the battery pack, and achieving the effect of reducing costs and increasing efficiency;

[0050] ③ When the electrical control system 4 determines that the SOC charge state of each subsystem in the main system differs by 1% from the initial state, the regulating valve 2 is used to regulate each component in the flow battery energy storage balancing system so that they can be charged and restored separately according to the difference between their respective systems, or they can be charged and restored together and then the charge state balancing and voltage balancing control procedures between subsystems are performed.

[0051] The following scheme takes two groups of subsystems connected in series and two stacks in parallel for each group of subsystems as an example:

[0052] (1) A balanced solution storage tank, a balanced stack and one of the two subsystems' electrolyte storage tanks in the balanced system form a set of liquid flow battery system, wherein the balanced solution storage tank is a positive electrode electrolyte storage tank of the balanced system, and the subsystem electrolyte storage tank is a negative electrode electrolyte storage tank of the balanced stack;

[0053] (2) The electrical control system reads and analyzes the values ​​of the SOC measuring devices in the two groups of subsystems, and adjusts the regulating valves in the balancing control component according to the read values ​​to control the different flow rates of the electrolyte storage tanks in the two groups of subsystems to flow through the balancing stack;

[0054] (3) The balancing circulation pump (i.e., the positive electrode circulation pump of the balancing system) pumps the solution in the balancing electrolyte storage tank (i.e., the positive electrode electrolyte storage tank of the balancing system) into the balancing stack with the sum of the flow rates of the two subsystems flowing through the balancing stack;

[0055] (4) The electrical control system reads and analyzes the values ​​of the SOC measuring devices in the two groups of subsystems, and controls the liquid flow battery system composed of the above (1) to automatically charge continuously or intermittently according to the read values, so as to balance and restore the SOC charge state of different subsystems of the main system, thereby improving the utilization rate of the electrolyte and the system efficiency, extending the battery life, and ensuring the battery performance;

[0056] (5) The solution in the equalizing electrolyte storage tank (i.e., the equalizing system positive electrode electrolyte storage tank) is a solution that can provide electrons and hydrogen ions under electrolysis conditions;

[0057] (6)① When the equalizing solution storage tank, the positive electrode electrolyte storage tanks of each subsystem in the main system and the equalizing stack form a liquid flow battery, taking the iron-chromium liquid flow battery and the all-vanadium liquid flow battery as examples, the reactions that occur in the equalizing stack during the electrolysis equalization process are as follows:

[0058] Equilibrium solution side in the stack: aR-ne - =bO / bO+ne - =aR;

[0059] Neutron system cathode electrolyte side of the fuel cell: Fe 3+ +e - =Fe 2+ / Fe 2+ -e - =Fe 3+

[0060]

[0061] ② When the equalizing solution storage tank, the negative electrode electrolyte storage tanks of each subsystem in the main system and the equalizing stack form a liquid flow battery, taking the iron-chromium liquid flow battery and the all-vanadium liquid flow battery as examples, the reactions that occur in the equalizing stack during the electrolysis equalization process are as follows:

[0062] Equilibrium solution side in the stack: aR-ne - =bO / bO+ne - =aR;

[0063] Anode electrolyte side of the stack neutron system: Cr 3+ +e - =Cr 2+ / Cr 2+ -e - =Cr 3+

[0064] / V 3+ +e - =V 2+ / V 2+ -e - =V 3+ ;

[0065] (7) The balancing system can automatically, continuously or intermittently balance the subsystems in the main system during operation. During the balancing process, the balancing pipelines are kept connected to ensure the consistency of the negative / positive electrolytes in the different subsystems of the main system.

[0066] Example 1

[0067] As shown below, a set of liquid circuit systems (Group A and Group B are two subsystems in the main system) built according to the above process are tested and verified. During the test, the flow rate, power and other parameters of the balancing system are analyzed and adjusted according to the actual operation of the supporting main system. The specific test results are as follows Figure 3-Figure 4 shown.

[0068] Figure 3 The SOC state of charge of the two subsystems of the main system varies with the cycle when the balancing system is operated according to certain parameters and the balancing system is not added. Figure 3 In the figure: (1) SOC state of charge is normalized with the OCV at the end of the first discharge cycle as 100%; (2) A-SOC, B-SOC: SOC state of charge of the system of group A and the system of group B without adding the balancing system; (3) JH-A-SOC, JH-B-SOC: SOC state of charge of the system of group A and the system of group B with adding the balancing system.

[0069] Figure 4 The figure shows the discharge capacity of the two subsystems with and without the equalization system. Figure 4In the figure: (1) the discharge capacity is normalized with the first cycle discharge capacity without adding the balancing system as 100%; (2) Discharge Energy (A+B) / % is the total system discharge capacity of the group A system + the group B system without adding the balancing system; (3) Discharge Energy [JH-(A+B)] / % is the total system discharge capacity of the group A system + the group B system with adding the balancing system.

[0070] From the above Figure 3 and Figure 4 It can be seen from the figure that when the balancing system is not added, the difference in SOC between the two groups of systems increases with operation due to the difference in electrolyte charge state caused by battery stack performance and attenuation, migration, leakage, etc., which further leads to a decrease in electrolyte utilization; when the balancing system is added, the SOC change trends of the two groups of subsystems tend to be consistent, the SOC difference decreases, and the electrolyte utilization rate increases, that is, the system energy density increases.

[0071] In summary, the liquid flow battery energy storage balancing system of the present invention can actively balance and restore the charge state between multiple process systems of the liquid flow battery energy storage system, improve the differences between systems, and is suitable for commercial liquid flow battery systems. It is widely promoted and applied in the fields of electrochemical energy storage technology research, engineering application of energy storage technology, etc.

[0072] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary engineering and technical personnel in the field should all fall within the protection scope of the claims of the present invention.

Claims

1. A flow battery energy storage equalization system, characterized in that: It includes a main system for providing power supply voltage and energy storage capacity, the main system is connected to a balancing system for balancing the capacity and voltage of the main system, and the liquid flow battery energy storage balancing system also includes an electrical control system connected to the main system and the balancing system.

2. A liquid flow battery energy storage equalization system as claimed in claim 1, characterized in that: The main system includes at least two subsystems, each of which includes an SOC meter, at least two subsystem electrolyte storage tanks and at least one subsystem battery stack. The SOC meter is connected to the subsystem electrolyte storage tanks and the subsystem battery stack, and a subsystem circulation pump is provided between each subsystem electrolyte storage tank and the subsystem battery stack.

3. A liquid flow battery energy storage equalization system as claimed in claim 2, characterized in that: The balancing system includes at least one balancing stack, the balancing stack is connected to a balancing control component and a balancing electrolyte storage tank, and a balancing circulation pump is arranged between the balancing electrolyte storage tank and the balancing stack.

4. A liquid flow battery energy storage equalization system as claimed in claim 3, characterized in that: The balancing system further comprises a balancing communication pipeline, and the main system and the balancing system are connected via the balancing communication pipeline.

5. A flow battery energy storage equalization system as claimed in claim 3, characterized in that: The balancing control component includes a regulating valve. The subsystem is connected to the balancing stack through two pipelines, and the regulating valve is arranged on the two pipelines.

6. A liquid flow battery energy storage equalization system as claimed in claim 5, characterized in that: The electrical control system is connected with the balancing stack, the SOC measuring device and the balancing control component.

7. A liquid flow battery energy storage balancing method, implemented based on a liquid flow battery energy storage balancing system according to any one of claims 1 to 6, characterized in that: The following steps are involved: The electrical control system obtains the SOC value of each subsystem in the main system, and adjusts the electrolyte flow of the main system through the balancing system according to the obtained SOC value, thereby achieving balance of the capacity and voltage of the main system.

8. A flow battery energy storage balancing method as claimed in claim 7, characterized in that: The following steps are involved: Determine the composition of the main system and the balancing system in the flow battery energy storage balancing system; The electrical control system obtains the SOC value of each subsystem in the main system; The electrical control system adjusts the flow of the electrolyte storage tank according to the obtained SOC value; The electrical control system adjusts the flow of the subsystem electrolyte storage tank in the subsystem according to the acquired SOC value.

9. A flow battery energy storage balancing method as claimed in claim 8, characterized in that: The determining of the composition of the main system and the balancing system in the liquid flow battery energy storage balancing system includes: determining the number of subsystems in the main system and the number of subsystem stacks in the subsystem according to demand.

10. A flow battery energy storage balancing method as claimed in claim 8, characterized in that: The electrical control system acquires the SOC value of each subsystem in the main system, including: the electrical control system acquires the SOC value of each subsystem through an SOC measuring device arranged in the subsystem.

11. A flow battery energy storage balancing method as claimed in claim 8, characterized in that: The electrical control system adjusts the flow of the balancing electrolyte storage tank according to the obtained SOC value, including: the electrical control system controls the balancing circulation pump to pump the solution in the balancing electrolyte storage tank into the balancing stack, and the pumping amount of the balancing circulation pump is the total flow of the main system flowing through the balancing stack.

12. A flow battery energy storage equalization method as claimed in claim 8, characterized in that: The electrical control system adjusts the flow of the subsystem electrolyte storage tank in the subsystem according to the acquired SOC value, including: when the electrical control system determines that the SOC charge state of each subsystem in the main system differs by 1%, opening the regulating valve and the balancing connecting pipeline, adjusting the flow of the subsystem electrolyte storage tank to make the SOC charge state of each subsystem consistent.

13. A flow battery energy storage balancing method as claimed in claim 8, characterized in that: The electrical control system adjusts the flow of the subsystem electrolyte storage tank in the subsystem according to the acquired SOC value, including: when the electrical control system determines that the SOC charge state of each subsystem in the main system is consistent and the overpotential is inconsistent, adjust the SOC charge state of each subsystem to make the charging and discharging voltage of each subsystem consistent.

14. A flow battery energy storage balancing method as claimed in claim 8, characterized in that: The electrical control system adjusts the flow of the subsystem electrolyte storage tank in the subsystem according to the acquired SOC value, including: when the electrical control system determines that the SOC charge state of each subsystem in the main system differs from the initial state by 1%, the liquid flow battery energy storage balancing system is regulated by the regulating valve to perform charging recovery, and after the charging recovery is completed, the charge state balancing and voltage balancing control procedures between the subsystems are performed.

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