Method and system for judging maximum power of flow battery according to flow coefficient

Abstract

The invention relates to a method and a system for judging the maximum power of a flow battery according to a flow coefficient. The method for judging the maximum charging power comprises the following steps of: selecting a charging test SOC (State of Charge) value, and taking the maximum current meeting a charging cut-off condition as the maximum charging current of the charging test SOC value; calculating a charging flow coefficient according to the charging test SOC value, the maximum charging current under the charging test SOC value, the single-side single-piece flow of the first electrolyte and the total vanadium concentration of the electrolyte; a charging target SOC value is selected, and the maximum charging current under the charging target SOC value is calculated according to the charging flow coefficient; calculating the theoretical voltage of the single battery under the charging target SOC value; and calculating the maximum charging power under the charging target SOC value. According to the method, the maximum charging and discharging power can be calculated through a theoretical formula on the basis of the flow coefficient obtained through actual measurement, the calculation efficiency is high, the safety risk of testing is reduced, and the reliability and universality of the system are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flow battery, in particular to a method and system for determining maximum power of flow battery according to flow coefficient. BACKGROUND

[0002] The flow battery management system needs to monitor the state of the system in real time and take necessary protection measures under extreme working conditions. One of the key protections is power protection. When the demand power or actual power of the system exceeds its safe bearing capacity, the BMS will trigger the shutdown protection to prevent system damage or safety accidents. Therefore, determining the maximum charging and discharging power boundary of the flow battery at different state of charge (SOC) is crucial for ensuring the safe, stable and long-life operation of the system.

[0003] In theory, the maximum charging and discharging power of the battery system at different SOC is dynamically changing. The most direct method to determine this power boundary is actual measurement. However, for large power energy storage battery systems, the maximum charging and discharging power is as high as hundreds of kilowatts or even thousands of kilowatts. The actual measurement of the limit power requires very high test equipment, huge cost, and significant safety hazards, which can easily cause irreversible damage to the battery stack, equipment and personnel. In addition, in order to overcome the defects of the actual measurement method, simulation modeling is used as an alternative means of power testing. However, in order to ensure the simulation accuracy, the grid density of the existing simulation method is usually high, which requires large computing power support and takes a long time.

[0004] Therefore, it is necessary to provide a new method for safely and quickly determining the maximum power of the flow battery. SUMMARY

[0005] Based on the above problems existing in the prior art, the purpose of the embodiments of the present application is to provide a method and system for determining the maximum power of the flow battery according to the flow coefficient. Based on the flow coefficient obtained by actual measurement, the maximum charging and discharging power can be calculated by a theoretical formula, which has high calculation efficiency, reduces the safety risk of testing, improves the overall operation economy and reliability of the system, and has strong universality.

[0006] To achieve the above purpose, the technical scheme adopted by the present application is: a method for determining the maximum power of the flow battery according to the flow coefficient, comprising: a method for determining the maximum charging power of the flow battery at different SOC according to the flow coefficient and a method for determining the maximum discharging power of the flow battery at different SOC according to the flow coefficient; The method for determining the maximum charging power of the flow battery at different SOC according to the flow coefficient comprises: Under the first electrolyte single-sided single piece flow, the charging test SOC value in the safe charging state is selected, the flow battery is charged with constant current, and the maximum current meeting the preset charging cutoff condition is the maximum charging current under the charging test SOC value; The charging flow coefficient is calculated according to the charging test SOC value, the maximum charging current under the charging test SOC value, the first electrolyte single-sided single piece flow and the total vanadium concentration of the electrolyte; The charging target SOC value of the maximum charging power to be determined is selected, and the maximum charging current under the charging target SOC value is calculated according to the charging flow coefficient, the electrolyte single-sided single piece flow under the charging target SOC value and the total vanadium concentration of the electrolyte; The theoretical voltage of the single piece battery under the charging target SOC value is calculated according to the maximum charging current under the charging target SOC value; The maximum charging power under the charging target SOC value is calculated according to the minimum value of the theoretical voltage of the single piece battery under the charging target SOC value and the charging cutoff voltage, and the maximum charging current under the charging target SOC value.

[0007] Further, the method for determining the maximum discharging power of the flow battery at different SOC values according to the flow coefficient comprises: Under the second electrolyte single-sided single piece flow, the discharging test SOC value in the safe discharging state is selected, the flow battery is discharged with constant current, and the maximum current meeting the preset discharging cutoff condition is the maximum discharging current under the discharging test SOC value; The discharging flow coefficient is calculated according to the discharging test SOC value, the maximum discharging current under the discharging test SOC value, the second electrolyte single-sided single piece flow and the total vanadium concentration of the electrolyte; The discharging target SOC value of the maximum discharging power to be determined is selected, and the maximum discharging current under the discharging target SOC value is calculated according to the discharging flow coefficient, the single-sided single piece flow under the discharging target SOC value and the total vanadium concentration of the electrolyte; The theoretical voltage of the single piece battery under the discharging target SOC value is calculated according to the maximum discharging current under the discharging target SOC value; The maximum discharging power under the discharging target SOC value is calculated according to the maximum value of the theoretical voltage of the single piece battery under the discharging target SOC value and the discharging cutoff voltage, and the maximum discharging current under the discharging target SOC value.

[0008] Further, the charging test SOC value is not higher than 50%; the preset charging cutoff condition includes that the single piece battery voltage is less than or equal to the charging cutoff voltage of the single piece battery and the charging time is greater than or equal to the preset charging time; The discharge test SOC value is not less than 50%; the preset discharge cutoff condition includes that the single cell voltage is greater than or equal to the discharge cutoff voltage of the single cell and the discharge time is greater than or equal to the preset discharge time.

[0009] Further, the charging flow coefficient calculation formula is:

[0010] wherein, k Qc is the charging flow coefficient, and the unit is 1; Q c is the first electrolyte single-sided single flow, and the unit is L / s; F is the Faraday constant, 96485 C / mol; cV is the total vanadium concentration of the electrolyte, and the unit is mol / L; is the charging test SOC value, is the maximum charging current under the charging test SOC value, and the unit is A; The discharge flow coefficient calculation formula is:

[0011] wherein, wherein, k Qf is the discharge flow coefficient, and the unit is 1; Q f is the second electrolyte single-sided single flow, and the unit is L / s; F is the Faraday constant, 96485 C / mol; cV is the total vanadium concentration of the electrolyte, and the unit is mol / L; is the discharge test SOC value, is the maximum discharge current under the discharge test SOC value, and the unit is A.

[0012] Further, the maximum charging current calculation formula under the charging target SOC value is:

[0013] wherein, is the maximum charging current under the charging target SOC value; is the electrolyte single-sided single flow under the charging target SOC value, and the unit is L / s; F is the Faraday constant, 96485 C / mol; cV is the total vanadium concentration of the electrolyte, and the unit is mol / L; is the charging target SOC value, k Qc is the charging flow coefficient, and the unit is 1; The maximum discharge current calculation formula under the discharge target SOC value is:

[0014] wherein, is the maximum discharge current at the discharge target SOC value; is the electrolyte single-sided single-piece flow at the discharge target SOC value, the unit is L / s; F is the Faraday constant, 96485 C / mol; cV is the total vanadium concentration of the electrolyte, the unit is mol / L; is the discharge target SOC value, k Qf is the discharge flow coefficient, the unit is 1.

[0015] Further, the theoretical voltage of the single-piece battery at the charging target SOC value is calculated according to the maximum charging current at the charging target SOC value, comprising: According to the maximum charging current at the charging target SOC value and the single-piece direct current internal resistance, the overpotential of the single-piece battery at the charging target SOC value is calculated; According to the overpotential of the single-piece battery at the charging target SOC value and the open-circuit voltage of the single-piece battery at the charging target SOC value, the theoretical voltage of the single-piece battery at the charging target SOC value is calculated.

[0016] Further, when the theoretical voltage of the single-piece battery at the charging target SOC value is less than or equal to the charging cutoff voltage, the maximum charging power at the charging target SOC value is calculated according to the following formula:

[0017] wherein, is the maximum charging power at the charging target SOC value, the unit is W; is the maximum charging current at the charging target SOC value, the unit is A; is the theoretical voltage of the single-piece battery at the charging target SOC value, the unit is V; pcs is the number of single-piece batteries in the flow battery stack; When the theoretical voltage of the single-piece battery at the charging target SOC value is greater than the charging cutoff voltage, the maximum charging power at the charging target SOC value is calculated according to the following formula:

[0018] wherein, is the maximum charging power at the charging target SOC value, the unit is W; is the maximum charging current at the charging target SOC value, the unit is A; is the charging cutoff voltage of the single-piece battery, the unit is V; pcs is the number of single-piece batteries in the flow battery stack.

[0019] Further, when the theoretical voltage of the single battery at the discharging target SOC value is greater than or equal to the discharging cutoff voltage, the maximum discharging power at the discharging target SOC value is calculated according to the following formula:

[0020] wherein, is the maximum discharging power at the discharging target SOC value, and the unit is W; is the maximum discharging current at the discharging target SOC value, and the unit is A; is the theoretical voltage of the single battery at the discharging target SOC value, and the unit is V; pcs is the number of single batteries in the flow battery stack; When the theoretical voltage of the single battery at the discharging target SOC value is less than the discharging cutoff voltage, the maximum discharging power at the discharging target SOC value is calculated according to the following formula:

[0021] wherein, is the maximum discharging power at the discharging target SOC value, and the unit is W; is the maximum discharging current at the discharging target SOC value, and the unit is A; is the discharging cutoff voltage of the single battery, and the unit is V; pcs is the number of single batteries in the flow battery stack.

[0022] A system for determining the maximum power of a flow battery according to a flow coefficient, applied to the method for determining the maximum power of a flow battery according to a flow coefficient, the system comprising a subsystem for determining the maximum charging power of a flow battery at different SOC values according to a flow coefficient and a subsystem for determining the maximum discharging power of a flow battery at different SOC values according to a flow coefficient: The subsystem for determining the maximum charging power of a flow battery at different SOC values according to a flow coefficient comprises: a measured maximum charging current acquisition module, configured to select a charging test SOC value in a charging safe state under a first electrolyte single-side single-flow, to charge the flow battery at a constant current, and to take the maximum current satisfying a preset charging cutoff condition as the maximum charging current at the charging test SOC value; a charging flow coefficient calculation module, configured to calculate a charging flow coefficient according to the charging test SOC value, the maximum charging current at the charging test SOC value, the first electrolyte single-side single-flow, and the total vanadium concentration of the electrolyte; a target maximum charging current calculation module, configured to select a charging target SOC value for which the maximum charging power is to be determined, and to calculate the maximum charging current at the charging target SOC value according to the charging flow coefficient, the electrolyte single-side single-flow at the charging target SOC value, and the total vanadium concentration of the electrolyte. a battery charging voltage parameter calculation module configured to calculate a theoretical voltage of a single battery at a charging target SOC value according to a maximum charging current at the charging target SOC value; a target maximum charging power calculation module configured to calculate a maximum charging power at the charging target SOC value according to a minimum value between the theoretical voltage of the single battery at the charging target SOC value and a charging cutoff voltage and the maximum charging current at the charging target SOC value.

[0023] Further, the subsystem for determining the maximum discharging power of the flow battery at different SOC values according to the flow coefficient comprises: a measured maximum discharging current acquisition module configured to select a discharging test SOC value at a discharging safe state under a second electrolyte single-side single-flow, to discharge the flow battery at a constant current, and to take a maximum current satisfying a preset discharging cutoff condition as a maximum discharging current at the discharging test SOC value; a discharging flow coefficient calculation module configured to calculate a discharging flow coefficient according to the discharging test SOC value, the maximum discharging current at the discharging test SOC value, the second electrolyte single-side single-flow and a total vanadium concentration of the electrolyte; a target maximum discharging current calculation module configured to select a discharging target SOC value, to calculate a maximum discharging current at the discharging target SOC value according to the discharging flow coefficient, the electrolyte single-side single-flow at the discharging target SOC value and the total vanadium concentration of the electrolyte; a battery discharging voltage parameter calculation module configured to calculate a theoretical voltage of a single battery at a discharging target SOC value according to a maximum discharging current at the discharging target SOC value; a target maximum discharging power calculation module configured to calculate a maximum discharging power at the discharging target SOC value according to a maximum value between the theoretical voltage of the single battery at the discharging target SOC value and a discharging cutoff voltage and the maximum discharging current at the discharging target SOC value.

[0024] The method for determining the maximum power of the flow battery according to the flow coefficient has the following advantages: the method only measures in a safe SOC interval to obtain a basic flow coefficient, avoids high-risk limit tests in a full SOC range, greatly reduces the probability of system damage and safety accidents, quickly calculates the maximum charging and discharging current and power at any SOC value based on the measured flow coefficient and a theoretical formula, does not need to rely on complex and time-consuming three-dimensional simulation, significantly improves the determination efficiency of the power boundary, ensures the reliability of the results based on the principle of balance between the supply and consumption of the flow battery reactants and the measured data correction, provides reliable shutdown protection criteria for the battery management system, ensures the safe operation of the system, avoids the decline of energy utilization rate caused by excessive power limitation, improves the overall operation economy and reliability of the system, and has high universality and practicality. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] In the picture: Figure 1 A flowchart of a method for determining the maximum charging power of a flow battery at different SOCs based on a flow coefficient, provided in the first embodiment of the present invention; Figure 2 A flowchart of a method for determining the maximum discharge power of a flow battery at different SOCs based on a flow coefficient, provided in the first embodiment of the present invention; Figure 3 A schematic diagram of a module for a subsystem that determines the maximum charging power of a flow battery at different SOCs based on a flow coefficient, as provided in the second embodiment of the present invention. Figure 4 A schematic diagram of a module for a subsystem that determines the maximum discharge power of a flow battery at different SOCs based on a flow coefficient, as provided in the second embodiment of the present invention. Figure 5 This is a schematic diagram of the network-side server provided according to the third embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] First implementation method: The first embodiment of the present invention provides a method for determining the maximum power of a flow battery based on a flow coefficient, including a method for determining the maximum charging power of a flow battery at different states of charge (SOC) based on a flow coefficient and a method for determining the maximum discharging power of a flow battery at different SOCs based on a flow coefficient.

[0029] The method for determining the maximum charging power of a flow battery under different SOCs based on the flow coefficient includes: selecting a test SOC value under a safe charging condition at a single-cell flow rate on one side of the first electrolyte, charging the flow battery with a constant current, and determining the maximum current that meets the preset charging cutoff condition as the maximum charging current at the test SOC value; calculating the charging flow coefficient based on the test SOC value, the maximum charging current at the test SOC value, the single-cell flow rate on one side of the first electrolyte, and the total vanadium concentration of the electrolyte; selecting a target SOC value for determining the maximum charging power, and calculating the maximum charging current at the target SOC value based on the charging flow coefficient, the single-cell flow rate on one side of the electrolyte, and the total vanadium concentration of the electrolyte; calculating the theoretical voltage of a single cell at the target SOC value based on the maximum charging current; and calculating the maximum charging power at the target SOC value based on the minimum of the theoretical voltage and the charging cutoff voltage of the single cell at the target SOC value, and the maximum charging current.

[0030] The method for determining the maximum discharge power of a flow battery under different SOCs based on the flow coefficient includes: selecting a discharge test SOC value under a safe discharge state at a single-cell flow rate on one side of the second electrolyte, discharging the flow battery with a constant current, and determining the maximum discharge current that meets the preset discharge cutoff condition as the maximum discharge current at the discharge test SOC value; calculating the discharge flow coefficient based on the discharge test SOC value, the maximum discharge current at the discharge test SOC value, the single-cell flow rate on one side of the second electrolyte, and the total vanadium concentration of the electrolyte; selecting a discharge target SOC value for which the maximum discharge power is to be determined, and calculating the maximum discharge current at the discharge target SOC value based on the discharge flow coefficient, the single-cell flow rate on one side of the electrolyte at the discharge target SOC value, and the total vanadium concentration of the electrolyte; calculating the theoretical voltage of a single cell at the discharge target SOC value based on the maximum discharge current at the discharge target SOC value; and calculating the maximum discharge power at the discharge target SOC value based on the maximum value between the theoretical voltage and the discharge cutoff voltage of the single cell at the discharge target SOC value, and the maximum discharge current at the discharge target SOC value.

[0031] The method for determining the maximum power of a flow battery based on the flow coefficient of this invention only requires actual measurement within the safe SOC range to obtain the basic flow coefficient, avoiding high-risk extreme testing across the entire SOC range, thus greatly reducing the probability of system damage and safety accidents. Based on the measured flow coefficient, the maximum charge and discharge current and power at any SOC can be quickly calculated using theoretical formulas, without relying on complex and time-consuming three-dimensional simulations, significantly improving the efficiency of determining the power boundary. Based on the principle of reactant supply and consumption balance in flow batteries, and combined with correction using measured data, the reliability of the results is ensured, providing a reliable shutdown protection criterion for the battery management system. This ensures safe system operation while avoiding the energy utilization rate reduction caused by excessive power limitation, improving the overall operating economy and reliability of the system, and demonstrating strong versatility and practicality.

[0032] The following uses a vanadium redox flow battery as an example to explain the implementation details of the method for determining the maximum power of a flow battery based on the flow coefficient in this embodiment. The following implementation details are provided for ease of understanding and are not essential for implementing this solution. The specific process of this embodiment is as follows: Figure 1 , Figure 2 As shown.

[0033] like Figure 1 As shown, methods for determining the maximum charging power of a flow battery at different SOCs based on the flow coefficient include: Step S11: Under the single-sided single-cell flow rate of the first electrolyte, select the SOC value of the charging test under the charging safety state, and charge the flow battery with a constant current. The maximum current that meets the preset charging cutoff condition is the maximum charging current of the charging test SOC value.

[0034] The single-sided flow rate of the electrolyte refers to the electrolyte flow rate on either the positive or negative electrode side of the flow battery. The single-sided single-cell flow rate refers to the electrolyte flow rate on either the positive or negative electrode side of a single cell. Either side can be selected for calculation; generally, the positive and negative electrode flow rates are the same. Once a side is selected, the subsequent electrolyte flow rate and total vanadium concentration will be calculated using the data from that side.

[0035] Specifically, the following steps are included: Step S111: Select a low SOC value (0~50%) under safe charging conditions as the SOC value for charging test. Since the overall battery voltage is low when the SOC value is low, the charging test is safer.

[0036] As an example, the SOC value for charging tests is selected. If the value is 0, proceed with the test.

[0037] Step S112, the preset charging cutoff conditions include a single battery voltage less than or equal to the charging cutoff voltage of a single battery and a charging time greater than or equal to a preset charging time.

[0038] As an example, the charging cutoff voltage for a single battery cell is 1.7V, and the preset charging time is 15s. The charging cutoff conditions are that the voltage of a single battery cell is ≤1.7V and the charging time is ≥15s.

[0039] Step S113: The flow battery is charged with constant currents of different gradients to obtain the maximum current that meets the preset charging cutoff condition, which is used as the maximum charging current under the SOC value of the charging test.

[0040] Step S12: Calculate the charging flow coefficient based on the SOC value of the charging test, the maximum charging current under the SOC value of the charging test, the single-sided single-cell flow rate of the first electrolyte, and the total vanadium concentration of the electrolyte.

[0041] Specifically, charging flow coefficient k Qc The calculation formula is:

[0042] in, k Qc This is the charging flow coefficient, with a unit of 1 and is dimensionless. Q c The flow rate of the first electrolyte is the flow rate of a single plate on one side, in L / s; F is the Faraday constant, 96485 C / mol. cV This is the total vanadium concentration of the electrolyte, expressed in mol / L. To test the SOC value for charging, The maximum charging current at the SOC value during the charging test, expressed in amperes (A).

[0043] If the flow rate of the first electrolyte is on one side of a single plate Q c Given the single-plate flow rate of the positive electrode electrolyte, then cV This refers to the total vanadium concentration in the positive electrode electrolyte. The total vanadium concentration in the electrolyte... cV Since the quantity is known, it can be directly substituted into the initial total vanadium concentration, or it can be obtained first through concentration testing.

[0044] It's important to note that in flow batteries, the electrolyte is supplied in a continuous flow, and the reactants, present within the electrolyte, are continuously supplied to the battery for reaction. When the flow rate, flow field, and current state of charge (SOC) are fixed, the amount of reactants supplied by the electrolyte flow is constant. As the current increases, the reactant consumption rate gradually increases until it equals the reactant supply rate from the electrolyte flow. This is the maximum charge / discharge current the battery can withstand. If the current continues to increase and the reactant consumption rate exceeds the reactant supply rate from the electrolyte flow, a rapid increase in local overpotential will occur, potentially causing system damage or abnormal capacity decay. Therefore, determining the maximum charge / discharge current the battery can withstand is equivalent to determining the equilibrium point between the reactant consumption rate and the reactant supply rate from the electrolyte flow.

[0045] Solving for the maximum current means solving for the actual flow rate of the reactants participating in the reaction. Because the flow field structure of a flow battery results in a non-uniform concentration throughout the reaction zone, not all reactants supplied to the reaction zone can effectively participate in the reaction. Therefore, the current flow rate cannot be directly equated to the actual flow rate of the reactants participating in the reaction; the current flow rate must be greater than the actual flow rate of the reactants participating in the reaction. Thus, it is necessary to solve for the ratio of the current flow rate to the actual flow rate of the reactants participating in the reaction, the flow coefficient.

[0046] Under the same flow field structure, the proportion of reactants that cannot effectively participate in the reaction is consistent across different SOCs due to uneven concentrations throughout the reaction zone. That is, it can be assumed that the flow coefficient is consistent at different SOCs when their respective maximum limiting currents are met. Therefore, as long as the stack structure, i.e., the flow field structure, remains unchanged, subsequent charging calculations at different SOCs can use the currently calculated charging flow coefficient. k Qc .

[0047] Step S13: Select the target SOC value for the maximum charging power to be determined, and calculate the maximum charging current under the target SOC value based on the charging flow coefficient, the single-sided single-plate flow rate of the electrolyte under the target SOC value, and the total vanadium concentration of the electrolyte.

[0048] Specifically, the formula for calculating the maximum charging current at the target SOC value is as follows:

[0049] in, The maximum charging current at the target SOC value, expressed in amperes (A). The electrolyte flow rate on one side of a single plate at the target SOC value is expressed in L / s; F is the Faraday constant, 96485 C / mol. cV This is the total vanadium concentration of the electrolyte, expressed in mol / L. The target SOC value for charging. k Qc This is the charging flow rate coefficient, with a unit of 1.

[0050] Step 14: Calculate the theoretical voltage of a single battery cell at the target SOC value based on the maximum charging current at the target SOC value.

[0051] Obtain the DC internal resistance and open-circuit voltage of a single cell, and calculate the overpotential and theoretical voltage of a single cell under the target SOC value.

[0052] Specifically, the DC internal resistance of a single cell is obtained using the DCR test method. Alternatively, a constant value method can be used to obtain the DC internal resistance of a single cell of the flow battery; for example, the DC internal resistance of a single cell is 0.0002Ω.

[0053] The single-cell open-circuit voltage of the flow battery at the target SOC value can be obtained through calculation using the Nernst equation or by actual measurement. .

[0054] The overpotential of a single cell at the target SOC value is calculated based on the maximum charging current and the single cell's DC internal resistance. The calculation formula is as follows:

[0055] in, The overpotential of a single battery cell at the target SOC value, expressed in V; The maximum charging current at the target SOC value is expressed in A; DCR is the DC internal resistance of a single chip, expressed in Ω.

[0056] The theoretical voltage of a single battery cell at the target SOC value is calculated based on the overpotential and open-circuit voltage of the single cell at the target SOC value. The calculation formula is as follows:

[0057] in, The theoretical voltage of a single battery cell at the target SOC value, expressed in volts (V). The overpotential of a single battery cell at the target SOC value, expressed in V; The open-circuit voltage of a single chip at the target SOC value for charging, in volts (V).

[0058] Step S15: Calculate the maximum charging power at the target SOC value based on the minimum of the theoretical voltage and charging cutoff voltage of a single battery cell at the target SOC value, and the maximum charging current at the target SOC value.

[0059] When the theoretical voltage of a single battery cell at the target SOC value is less than or equal to the charging cut-off voltage, the maximum charging power at the target SOC value is calculated based on the theoretical voltage of the single battery cell at the target SOC value, the maximum charging current at the target SOC value, and the number of flow batteries. When the theoretical voltage of a single battery cell at the target SOC value is greater than the charging cut-off voltage, the maximum charging power at the target SOC value is calculated based on the charging cut-off voltage, the maximum charging current at the target SOC value, and the number of flow batteries.

[0060] Specifically, when the theoretical voltage of a single battery cell is less than or equal to the charging cutoff voltage at the target SOC value, the formula for calculating the maximum charging power at the target SOC value is:

[0061] in, The maximum charging power at the target SOC value, expressed in watts (W). The maximum charging current at the target SOC value, in amperes (A). The theoretical voltage of a single battery cell at the target SOC value, expressed in volts (V). pcs This refers to the number of individual battery cells in a flow battery stack.

[0062] When the theoretical voltage of a single battery cell is greater than the charging cutoff voltage at the target SOC value, the formula for calculating the maximum charging power at the target SOC value is:

[0063] in, The maximum charging power at the target SOC value, expressed in watts (W). The maximum charging current at the target SOC value, in amperes (A). This is the charging cutoff voltage for a single battery cell, expressed in volts (V). pcs This refers to the number of individual battery cells in a flow battery stack.

[0064] like Figure 2 As shown, methods for determining the maximum discharge power of a flow battery at different SOCs based on the flow coefficient include: Step S21: Under the single-sided single-cell flow rate of the second electrolyte, select the discharge test SOC value under the discharge safety state, and discharge the flow battery with a constant current. The maximum current that meets the preset discharge cutoff condition is the maximum discharge current under the discharge test SOC value.

[0065] The single-sided flow rate of the electrolyte refers to the electrolyte flow rate on either the positive or negative electrode side of the flow battery. The single-sided single-cell flow rate refers to the electrolyte flow rate on either the positive or negative electrode side of a single cell. Either side can be selected for calculation; generally, the positive and negative electrode flow rates are the same. Once a side is selected, the subsequent electrolyte flow rate and total vanadium concentration will be calculated using the data from that side.

[0066] Specifically, the following steps are included: Step S211: Select a high SOC value (51% to 100%) of the safe discharge state as the discharge test SOC value. Since the overall voltage is higher when the SOC value is high, it is easier to test the maximum discharge current.

[0067] As an example, the SOC value selected for discharge testing is... To achieve 100%, conduct the test.

[0068] Step S212, the preset discharge cutoff conditions include a single cell voltage greater than or equal to the single cell discharge cutoff voltage and a discharge time greater than or equal to a preset discharge time.

[0069] As an example, the discharge cutoff voltage of a single battery is 1V, and the preset discharge time is 15s. The discharge cutoff conditions in this case are that the voltage of a single battery is ≥1V and the discharge time is ≥15s.

[0070] Step S213: Discharge the flow battery with constant currents of different gradients to obtain the maximum current that meets the preset discharge cutoff condition, which is used as the maximum discharge current under the discharge test SOC value.

[0071] Step S22: Calculate the discharge flow coefficient based on the discharge test SOC value, the maximum discharge current under the discharge test SOC value, the single-sided single-plate flow rate of the second electrolyte, and the total vanadium concentration of the electrolyte.

[0072] Specifically, the discharge flow coefficient k Qf The calculation formula is:

[0073] Among them, among them, k Qf This is the discharge flow coefficient, with a unit of 1; Q f The flow rate of the second electrolyte is the flow rate of a single plate on one side, in L / s; F is the Faraday constant, 96485 C / mol. cV This is the total vanadium concentration of the electrolyte, expressed in mol / L. To test the SOC value during discharge, This represents the maximum discharge current at the SOC value during the discharge test, expressed in amperes (A).

[0074] If the flow rate of the second electrolyte is only on one side of a single plate Q f Given the single-plate flow rate of the positive electrode electrolyte, then cV This refers to the total vanadium concentration in the positive electrode electrolyte. The total vanadium concentration in the electrolyte... cV Since the quantity is known, the initial total vanadium concentration can be used directly.

[0075] It's important to note that in flow batteries, the electrolyte is supplied in a continuous flow, and the reactants, present within the electrolyte, are continuously supplied to the battery for reaction. When the flow rate, flow field, and current state of charge (SOC) are fixed, the amount of reactants supplied by the electrolyte flow is constant. As the current increases, the reactant consumption rate gradually increases until it equals the reactant supply rate from the electrolyte flow. This is the maximum charge / discharge current the battery can withstand. If the current continues to increase and the reactant consumption rate exceeds the reactant supply rate from the electrolyte flow, a rapid increase in local overpotential will occur, potentially causing system damage or abnormal capacity decay. Therefore, determining the maximum charge / discharge current the battery can withstand is equivalent to determining the equilibrium point between the reactant consumption rate and the reactant supply rate from the electrolyte flow.

[0076] Solving for the maximum current means solving for the actual flow rate of the reactants participating in the reaction. Because the flow field structure of a flow battery results in a non-uniform concentration throughout the reaction zone, not all reactants supplied to the reaction zone can effectively participate in the reaction. Therefore, the current flow rate cannot be directly equated to the actual flow rate of the reactants participating in the reaction; the current flow rate must be greater than the actual flow rate of the reactants participating in the reaction. Thus, it is necessary to solve for the ratio of the current flow rate to the actual flow rate of the reactants participating in the reaction, the flow coefficient.

[0077] Under the same flow field structure, the proportion of reactants that cannot effectively participate in the reaction is consistent across different SOCs due to uneven concentrations throughout the reaction zone. That is, it can be assumed that the flow coefficient is consistent at different SOCs when their respective maximum limiting currents are met. Therefore, as long as the stack structure, i.e., the flow field structure, remains unchanged, subsequent discharge calculations at different SOCs can use the currently calculated discharge flow coefficient. k Qf .

[0078] Step S23: Select the target SOC value for the maximum discharge power to be determined, and calculate the maximum discharge current under the target SOC value based on the discharge flow coefficient, the single-sided single-plate flow rate of the electrolyte under the target SOC value, and the total vanadium concentration of the electrolyte.

[0079] Specifically, the formula for calculating the maximum discharge current at the target SOC value is as follows:

[0080] in, This represents the maximum discharge current at the target SOC value. The electrolyte flow rate on one side of a single plate at the target SOC value is expressed in L / s; F is the Faraday constant, 96485 C / mol. cV This is the total vanadium concentration of the electrolyte, expressed in mol / L. The target SOC value for discharge. k Qf This is the discharge flow coefficient, with a unit of 1.

[0081] Step S24: Calculate the theoretical voltage of a single cell at the target SOC value based on the maximum discharge current at the target SOC value.

[0082] Obtain the DC internal resistance and open-circuit voltage of a single cell, and calculate the overpotential and theoretical voltage of a single cell.

[0083] Specifically, the DC internal resistance of a single cell is obtained using the DCR test method. Alternatively, a constant value method can be used to obtain the DC internal resistance of a single cell of the flow battery; for example, the DC internal resistance of a single cell is 0.0002Ω.

[0084] The single-cell open-circuit voltage of the flow battery at the target discharge SOC value is obtained through calculation using the Nernst equation or by actual measurement. .

[0085] The formula for calculating the overpotential of a single cell is:

[0086] in, The overpotential of a single cell at the target SOC value for discharge, expressed in V; The maximum discharge current at the target SOC value is expressed in A; DCR is the single-chip DC internal resistance, expressed in Ω.

[0087] The theoretical voltage calculation formula for a single battery cell is as follows:

[0088] in, The theoretical voltage of a single cell at the target SOC value for discharge, in V; The overpotential of a single cell at the target SOC value for discharge, expressed in V; The open-circuit voltage of a single chip at the target SOC value for discharge, in volts (V).

[0089] Step S25: Calculate the maximum discharge power at the target SOC value based on the maximum value of the theoretical voltage and discharge cutoff voltage of a single battery cell at the target SOC value, and the maximum discharge current at the target SOC value.

[0090] When the theoretical voltage of a single cell at the target discharge SOC is greater than or equal to the discharge cutoff voltage, the maximum discharge power at the target discharge SOC is calculated based on the theoretical voltage of the single cell at the target discharge SOC, the maximum discharge current at the target discharge SOC, and the number of flow batteries. When the theoretical voltage of a single cell at the target discharge SOC is less than the discharge cutoff voltage, the maximum discharge power at the target discharge SOC is calculated based on the discharge cutoff voltage, the maximum discharge current at the target discharge SOC, and the number of flow batteries.

[0091] Specifically, when the theoretical voltage of a single battery cell is greater than or equal to the discharge cutoff voltage at the target discharge SOC value, the formula for calculating the maximum discharge power at the target discharge SOC value is:

[0092] in, The maximum discharge power at the target SOC value is expressed in W. The maximum discharge current at the target SOC value is expressed in amperes (A). The theoretical voltage of a single cell at the target SOC value for discharge, in V; pcs This refers to the number of individual battery cells in a flow battery stack.

[0093] When the theoretical voltage of a single battery cell is less than the discharge cutoff voltage at the target discharge SOC value, the formula for calculating the maximum discharge power at the target discharge SOC value is:

[0094] in, The maximum discharge power at the target SOC value is expressed in W. The maximum discharge current at the target SOC value is expressed in amperes (A). This is the discharge cutoff voltage of a single battery cell, expressed in volts (V). pcs This refers to the number of individual battery cells in a flow battery stack.

[0095] This invention provides a method for determining the maximum power of a flow battery based on its flow coefficient. This method involves conducting measurements only within the safe State of Charge (SOC) range to obtain a baseline flow coefficient, avoiding high-risk extreme testing across the entire SOC range and significantly reducing the probability of system damage and safety accidents. Based on the measured flow coefficient, the maximum charge / discharge current and power at any SOC can be quickly calculated using theoretical formulas, eliminating the need for complex and time-consuming 3D simulations and significantly improving the efficiency of power boundary determination. Based on the principle of reactant supply and consumption balance in flow batteries, and corrected using measured data, the reliability of the results is ensured. This provides a reliable shutdown protection criterion for the battery management system, ensuring safe system operation while avoiding excessive power limitation that leads to decreased energy utilization. This improves the overall economic efficiency and reliability of the system, and demonstrates strong versatility and practicality.

[0096] The determination method provided in this application can be used for vanadium redox flow batteries as well as other flow batteries. When used for other batteries, the determination principle is the same; simply adjust the corresponding charge and discharge cutoff conditions according to the battery parameters and replace the total vanadium concentration of the electrolyte with the corresponding active material concentration.

[0097] Specific examples are as follows: Example 1 Assemble an all-vanadium redox flow stack containing 30 single-cell batteries. The electrolyte is vanadium electrolyte, with a single-cell flow rate of 0.06 L / s for both positive and negative electrodes, a total vanadium concentration of 1.65 mol / L for both electrodes, and a total electrolyte volume of 2 m³. 3 The temperature is 37℃.

[0098] Maximum charging power is determined by selecting the SOC value during charging testing. =10% state. The charging cutoff voltage for a single battery cell is 1.7V, and the preset charging time is 15s. The charging cutoff conditions at this point are that the voltage of a single battery cell ≤ 1.7V and the charging time ≥ 15s. Charging was performed at currents of 3800A, 4000A, and 4200A, with charging times of 30s, 15s, and 7s respectively.

[0099] therefore, Maximum charging current at 10% =4000A.

[0100] The test was calculated. Below, the current is Flow coefficient at time .

[0101] Select target SOC value for charging =70%, at this point the flow rate remains unchanged, according to the charging flow rate coefficient. The maximum charging current at the target SOC value is calculated based on a single-sided single-cell flow rate of 0.06 L / s and a total vanadium concentration of 1.65 mol / L in the electrolyte. .

[0102] Calculate the target SOC value for charging The overpotential of a single cell at 70% is ,in DCR =0.0002Ω; according to the measured data, the open circuit voltage at this time is 1.43V. The theoretical voltage of a single cell is calculated to be 1.6965V, which is less than the cutoff voltage of 1.7V.

[0103] Finally, the target SOC value for charging was calculated. At 70%, maximum charging power .

[0104] It should be noted that by changing the target SOC value and repeating the above steps, a table of maximum charging power under different SOCs can be obtained.

[0105] Example 2 The flow field structure and parameters of the flow battery in this example are the same as in Example 1, and will not be repeated here.

[0106] The maximum discharge power is determined by selecting the SOC value during the discharge test. =90% state. The discharge cutoff voltage of a single battery is 1V, and the preset discharge time is 15s. The discharge cutoff conditions at this time are that the voltage of a single battery is ≥1V and the discharge time is ≥15s. Discharge was carried out with currents of 3300A, 3750A, and 4100A respectively, with discharge times of 30s, 15s, and 7s respectively.

[0107] therefore, Maximum discharge current at 90% =3750A.

[0108] The test was calculated. At 90%, the current is Flow coefficient at time .

[0109] Select the target SOC value for discharge =20%, at this point the flow rate remains constant, according to the discharge flow coefficient The maximum discharge current at the target SOC value was calculated based on a single-sided single-cell flow rate of 0.06 L / s and a total vanadium concentration of 1.65 mol / L in the electrolyte. .

[0110] Subsequently, based on the SOC value Given that the maximum current at 20% SOC is 834.24A, calculate the maximum discharge power at 20% SOC. .

[0111] Calculate the SOC value of the discharge target The overpotential of a single cell at 20% is Where DCR = 0.0002Ω; according to the measured data, the open circuit voltage is 1.33V. The theoretical voltage of a single cell is calculated to be 1.1632V, which is greater than the cutoff voltage by 1V.

[0112] Finally, the SOC value of the discharge target was calculated. At 20%, the maximum discharge power .

[0113] It should be noted that by changing the target discharge SOC value and repeating the above steps, a table of maximum discharge power under different SOCs can be obtained.

[0114] like Figure 3 , Figure 4 As shown, the second embodiment of the present invention provides a system for determining the maximum power of a flow battery based on a flow coefficient, including a subsystem for determining the maximum charging power of the flow battery at different SOCs based on a flow coefficient and a subsystem for determining the maximum discharging power of the flow battery at different SOCs based on a flow coefficient.

[0115] like Figure 3 As shown, the subsystem for determining the maximum charging power of a flow battery under different SOCs based on the flow coefficient includes: a measured maximum charging current acquisition module 301, a charging flow coefficient calculation module 302, a target maximum charging current calculation module 303, a battery charging voltage parameter calculation module 304, and a target maximum charging power calculation module 305.

[0116] Specifically, the measured maximum charging current acquisition module 301 is used to select the charging test SOC value under the charging safety state under the single-sided single-cell flow rate of the first electrolyte, and charge the flow battery with a constant current. The maximum current that meets the preset charging cutoff condition is the maximum charging current under the charging test SOC value. The charging flow coefficient calculation module 302 is used to calculate the charging flow coefficient based on the charging test SOC value, the maximum charging current under the charging test SOC value, the single-sided single-cell flow rate of the first electrolyte, and the total vanadium concentration of the electrolyte. The target maximum charging current calculation module 303 is used to select the charging current at which the maximum charging power to be determined is... The target SOC value is calculated based on the charging flow coefficient, the single-sided single-cell flow rate of the electrolyte at the target SOC value, and the total vanadium concentration of the electrolyte, to obtain the maximum charging current at the target SOC value. The battery charging voltage parameter calculation module 304 is used to calculate the theoretical voltage of a single cell at the target SOC value based on the maximum charging current. The target maximum charging power calculation module 305 is used to calculate the maximum charging power at the target SOC value based on the minimum value between the theoretical voltage and the charging cutoff voltage of a single cell at the target SOC value, and the maximum charging current at the target SOC value.

[0117] like Figure 4 As shown, the subsystem for determining the maximum discharge power of a flow battery under different SOCs based on the flow coefficient includes: a measured maximum discharge current acquisition module 401, a discharge flow coefficient calculation module 402, a target maximum discharge current calculation module 403, a battery discharge voltage parameter calculation module 404, and a target maximum discharge power calculation module 405.

[0118] Specifically, the measured maximum discharge current acquisition module 401 is used to select the discharge test SOC value under the discharge safety state under the single-sided single-cell flow rate of the second electrolyte, and discharge the flow battery with a constant current. The maximum current that meets the preset discharge cutoff condition is the maximum discharge current under the discharge test SOC value. The discharge flow coefficient calculation module 402 is used to calculate the discharge flow coefficient based on the discharge test SOC value, the maximum discharge current under the discharge test SOC value, the single-sided single-cell flow rate of the second electrolyte, and the total vanadium concentration of the electrolyte. The target maximum discharge current calculation module 403 is used to select the discharge current at which the maximum discharge power to be determined is... The target SOC value is calculated based on the discharge flow coefficient, the single-sided single-cell flow rate of the electrolyte at the target SOC value, and the total vanadium concentration of the electrolyte, to obtain the maximum discharge current at the target SOC value. The battery discharge voltage parameter calculation module 404 is used to calculate the theoretical voltage of a single cell at the target SOC value based on the maximum discharge current. The target maximum discharge power calculation module 405 is used to calculate the maximum discharge power at the target SOC value based on the maximum value between the theoretical voltage and the discharge cutoff voltage of a single cell at the target SOC value, and the maximum discharge current at the target SOC value.

[0119] It is not difficult to see that this embodiment is a system implementation corresponding to the first embodiment, and this embodiment can be implemented in conjunction with the first embodiment. The relevant technical details mentioned in the first embodiment are still valid in this embodiment, and will not be repeated here to reduce repetition. Accordingly, the relevant technical details mentioned in this embodiment can also be applied to the first embodiment.

[0120] It is worth mentioning that all modules involved in this embodiment are logical modules. In practical applications, a logical unit can be a physical unit, a part of a physical unit, or a combination of multiple physical units. Furthermore, to highlight the innovative aspects of this invention, this embodiment does not introduce units that are not closely related to solving the technical problem proposed by this invention; however, this does not mean that other units are absent from this embodiment.

[0121] The third embodiment of the present invention relates to a network-side server, such as... Figure 5 As shown, it includes at least one processor 302; and a memory 301 communicatively connected to at least one processor 302; wherein the memory 301 stores instructions executable by at least one processor 302, the instructions being executed by at least one processor 302 to enable at least one processor 302 to perform the above-described data processing method.

[0122] The memory 301 and processor 302 are connected via a bus, which may include any number of interconnecting buses and bridges. The bus connects various circuits of one or more processors 302 and memory 301 together. The bus can also connect various other circuits, such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described further herein. A bus interface provides an interface between the bus and the transceiver. The transceiver can be a single element or multiple elements, such as multiple receivers and transmitters, providing a unit for communicating with various other devices over a transmission medium. Data processed by processor 302 is transmitted over a wireless medium via an antenna, which further receives data and transmits it to processor 302.

[0123] Processor 302 is responsible for managing the bus and general processing, and can also provide various functions, including timing, peripheral interfaces, voltage regulation, power management, and other control functions. Memory 301 can be used to store data used by processor 302 during operation.

[0124] The fourth embodiment of the present invention relates to a computer-readable storage medium storing a computer program. When executed by a processor, the computer program implements the method for determining the maximum power of a flow battery based on a flow coefficient as described in the first embodiment.

[0125] That is, those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. This program is stored in a storage medium and includes several instructions to cause a device (which may be a microcontroller, chip, etc.) or processor to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0126] The above descriptions are merely embodiments of the present invention. Commonly known structures and characteristics are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

[0127] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for determining the maximum power of a flow battery based on its flow coefficient, characterized in that, This includes methods for determining the maximum charging power of a flow battery at different SOCs based on the flow coefficient and methods for determining the maximum discharging power of a flow battery at different SOCs based on the flow coefficient. The method for determining the maximum charging power of a flow battery at different SOCs based on the flow coefficient includes: Under the single-sided single-cell flow rate of the first electrolyte, the SOC value of the charging test under the charging safety state is selected, and the flow battery is charged with a constant current. The maximum current that meets the preset charging cutoff condition is the maximum charging current under the charging test SOC value. The charging flow coefficient is calculated based on the SOC value of the charging test, the maximum charging current under the SOC value of the charging test, the single-sided single-cell flow rate of the first electrolyte, and the total vanadium concentration of the electrolyte. Select the target SOC value for charging, and calculate the maximum charging current under the target SOC value based on the charging flow coefficient, the single-sided single-cell flow rate of the electrolyte under the target SOC value, and the total vanadium concentration of the electrolyte. Calculate the theoretical voltage of a single cell at the target SOC value based on the maximum charging current at the target SOC value. The maximum charging power at the target SOC value is calculated based on the minimum of the theoretical voltage and the charging cutoff voltage of a single cell at the target SOC value, and the maximum charging current at the target SOC value.

2. The method for determining the maximum power of a flow battery based on the flow coefficient according to claim 1, characterized in that, The method for determining the maximum discharge power of a flow battery at different SOCs based on the flow coefficient includes: Under the single-sided single-cell flow rate of the second electrolyte, the discharge test SOC value under the discharge safety state is selected, and the flow battery is discharged with a constant current. The maximum current that meets the preset discharge cutoff condition is the maximum discharge current under the discharge test SOC value. The discharge flow coefficient is calculated based on the discharge test SOC value, the maximum discharge current under the discharge test SOC value, the single-sided single-plate flow rate of the second electrolyte, and the total vanadium concentration of the electrolyte. Select the target SOC value for discharge, and calculate the maximum discharge current under the target SOC value based on the discharge flow coefficient, the single-sided single-plate flow rate of the electrolyte under the target SOC value, and the total vanadium concentration of the electrolyte. Calculate the theoretical voltage of a single cell at the target SOC value based on the maximum discharge current at the target SOC value. The maximum discharge power at the target SOC value is calculated based on the maximum value of the theoretical voltage and discharge cutoff voltage of a single cell at the target SOC value, and the maximum discharge current at the target SOC value.

3. The method for determining the maximum power of a flow battery based on the flow coefficient according to claim 2, characterized in that, The SOC value of the charging test is not higher than 50%; the preset charging cutoff conditions include that the voltage of a single battery cell is less than or equal to the charging cutoff voltage of a single battery cell and the charging time is greater than or equal to the preset charging time. The discharge test SOC value is not less than 50%; the preset discharge cutoff conditions include a single cell voltage greater than or equal to the single cell discharge cutoff voltage and a discharge time greater than or equal to a preset discharge time.

4. The method for determining the maximum power of a flow battery based on the flow coefficient according to claim 2, characterized in that, The formula for calculating the charging flow coefficient is: in, k Qc This is the charging flow coefficient, with a unit of 1. Q c The flow rate of the first electrolyte is the flow rate of a single plate on one side, in L / s; F is the Faraday constant, 96485 C / mol. cV This is the total vanadium concentration of the electrolyte, expressed in mol / L. To test the SOC value for charging, The maximum charging current at the SOC value for charging testing, in amperes (A). The formula for calculating the discharge flow coefficient is: in, k Qf This is the discharge flow coefficient, with a unit of 1; Q f The flow rate of the second electrolyte is the flow rate of a single plate on one side, in L / s; F is the Faraday constant, 96485 C / mol. cV This is the total vanadium concentration of the electrolyte, expressed in mol / L. To test the SOC value during discharge, This represents the maximum discharge current at the SOC value during the discharge test, expressed in amperes (A).

5. The method for determining the maximum power of a flow battery based on the flow coefficient according to claim 2, characterized in that, The formula for calculating the maximum charging current under the target SOC value is as follows: in, The maximum charging current at the target SOC value; The electrolyte flow rate on one side of a single plate at the target SOC value is expressed in L / s; F is the Faraday constant, 96485 C / mol. cV This is the total vanadium concentration of the electrolyte, expressed in mol / L. The target SOC value for charging. k Qc This is the charging flow coefficient, with a unit of 1. The formula for calculating the maximum discharge current at the target SOC value is as follows: in, This represents the maximum discharge current at the target SOC value. The electrolyte flow rate on one side of a single plate at the target SOC value is expressed in L / s; F is the Faraday constant, 96485 C / mol. cV This is the total vanadium concentration of the electrolyte, expressed in mol / L. The target SOC value for discharge. k Qf This is the discharge flow coefficient, with a unit of 1.

6. The method for determining the maximum power of a flow battery based on the flow coefficient according to claim 1, characterized in that, The step of calculating the theoretical voltage of a single battery cell at the target SOC value based on the maximum charging current at the target SOC value includes: The overpotential of a single cell at the target SOC value is calculated based on the maximum charging current and the single cell's DC internal resistance. The theoretical voltage of a single cell at the target SOC value is calculated based on the overpotential and open-circuit voltage of the single cell at the target SOC value.

7. The method for determining the maximum power of a flow battery based on the flow coefficient according to claim 1, characterized in that, When the theoretical voltage of a single battery cell is less than or equal to the charging cutoff voltage at the target SOC value, the formula for calculating the maximum charging power at the target SOC value is: in, The maximum charging power at the target SOC value, expressed in watts (W). The maximum charging current at the target SOC value, in amperes (A). The theoretical voltage of a single battery cell at the target SOC value, expressed in volts (V). pcs This refers to the number of individual battery cells in a flow battery stack. When the theoretical voltage of a single battery cell is greater than the charging cutoff voltage at the target SOC value, the formula for calculating the maximum charging power at the target SOC value is: in, The maximum charging power at the target SOC value, expressed in watts (W). The maximum charging current at the target SOC value, in amperes (A). This is the charging cutoff voltage for a single battery cell, expressed in volts (V). pcs This refers to the number of individual battery cells in a flow battery stack.

8. The method for determining the maximum power of a flow battery based on the flow coefficient according to claim 2, characterized in that, When the theoretical voltage of a single battery cell is greater than or equal to the discharge cutoff voltage at the target discharge SOC value, the formula for calculating the maximum discharge power at the target discharge SOC value is: in, The maximum discharge power at the target SOC value is expressed in W. The maximum discharge current at the target SOC value is expressed in amperes (A). The theoretical voltage of a single cell at the target SOC value for discharge, in V; pcs This refers to the number of individual battery cells in a flow battery stack. When the theoretical voltage of a single battery cell is less than the discharge cutoff voltage at the target discharge SOC value, the formula for calculating the maximum discharge power at the target discharge SOC value is: in, The maximum discharge power at the target SOC value is expressed in W. The maximum discharge current at the target SOC value, in amperes (A). This is the discharge cutoff voltage of a single battery cell, expressed in volts (V). pcs This refers to the number of individual battery cells in a flow battery stack.

9. A system for determining the maximum power of a flow battery based on its flow coefficient, characterized in that, The method for determining the maximum power of a flow battery based on a flow coefficient according to any one of claims 1-8, wherein the system comprises a subsystem for determining the maximum charging power of the flow battery at different states of charge (SOC) based on a flow coefficient and a subsystem for determining the maximum discharging power of the flow battery at different SOCs based on a flow coefficient: The subsystem for determining the maximum charging power of a flow battery at different SOCs based on the flow coefficient includes: The measured maximum charging current acquisition module is used to select the charging test SOC value under the charging safety state under the single-sided single-cell flow rate of the first electrolyte, and charge the flow battery with a constant current. The maximum current that meets the preset charging cutoff condition is the maximum charging current under the charging test SOC value. The charging flow coefficient calculation module is used to calculate the charging flow coefficient based on the charging test SOC value, the maximum charging current under the charging test SOC value, the single-sided single-cell flow rate of the first electrolyte, and the total vanadium concentration of the electrolyte. The target maximum charging current calculation module is used to select the target SOC value and calculate the maximum charging current under the target SOC value based on the charging flow coefficient, the single-sided single-cell flow rate of the electrolyte under the target SOC value, and the total vanadium concentration of the electrolyte. The battery charging voltage parameter calculation module is used to calculate the theoretical voltage of a single battery cell at the target SOC value based on the maximum charging current at the target SOC value. The target maximum charging power calculation module is used to calculate the maximum charging power under the target SOC value based on the minimum of the theoretical voltage and charging cutoff voltage of a single battery cell under the target SOC value, and the maximum charging current under the target SOC value.

10. The system for determining the maximum power of a flow battery based on the flow coefficient according to claim 9, characterized in that, The subsystem for determining the maximum discharge power of a flow battery at different SOCs based on the flow coefficient includes: The measured maximum discharge current acquisition module is used to select the discharge test SOC value under the discharge safety state under the single-sided single-cell flow rate of the second electrolyte, and discharge the flow battery with a constant current. The maximum current that meets the preset discharge cutoff condition is the maximum discharge current under the discharge test SOC value. The discharge flow coefficient calculation module is used to calculate the discharge flow coefficient based on the discharge test SOC value, the maximum discharge current under the discharge test SOC value, the single-sided single-plate flow rate of the second electrolyte, and the total vanadium concentration of the electrolyte. The target maximum discharge current calculation module is used to select the target SOC value for discharge and calculate the maximum discharge current under the target SOC value based on the discharge flow coefficient, the single-sided single-plate flow rate of the electrolyte under the target SOC value, and the total vanadium concentration of the electrolyte. The battery discharge voltage parameter calculation module is used to calculate the theoretical voltage of a single battery cell at the target discharge SOC value based on the maximum discharge current at the target discharge SOC value. The target maximum discharge power calculation module is used to calculate the maximum discharge power at the target SOC value based on the maximum value of the theoretical voltage and discharge cutoff voltage of a single battery cell at the target SOC value, and the maximum discharge current at the target SOC value.

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