Method and system for real-time adjustment of SOC of flow battery energy storage power station for frequency modulation

Abstract

The invention belongs to the technical field of electric power energy storage, and particularly discloses a real-time SOC adjustment method and system for a flow battery energy storage power station for frequency modulation, and the method comprises the steps: obtaining the current SOC value and the SOC mean value of each power unit in the flow battery energy storage power station for frequency modulation; judging whether the current SOC value of each power unit meets a first adjustment condition or not; if the current SOC values of a plurality of first power units meet the first adjustment condition, selecting a first SOC adjustment target value of each first power unit; based on the deviation between the current SOC value of each first power unit and the SOC mean value and the selected first SOC adjustment target value, determining the charging and discharging priority of each first power unit; and selecting the first target power unit to carry out SOC out-of-limit adjustment based on the charging and discharging priority. According to the method, the SOC of the auxiliary frequency modulation or independent frequency modulation flow battery energy storage power station is effectively prevented from touching charging and discharging limitation or cut-off conditions, and execution of the frequency modulation instruction is guaranteed.

Description

Technical Field

[0001] The present application belongs to the field of electric energy storage technology, and more specifically, relates to a method and system for real-time adjustment of SOC of a liquid flow battery energy storage power station for frequency modulation. Background Art

[0002] Electrochemical energy storage technology has become an important means of stabilizing the frequency of power grids in new power systems due to its fast response speed and strong adaptability. At present, the engineering application of electrochemical energy storage frequency regulation mainly includes two parts: one is to assist thermal power units in frequency regulation, and the other is to participate in grid frequency regulation as an independent power source.

[0003] In the conditions where an electrochemical energy storage power station assists thermal power units in frequency regulation or participates in grid frequency regulation as an independent power source, when the state of charge (SOC) of the electrochemical energy storage power station reaches the preset cutoff condition, the corresponding protection mechanism will be triggered, and the upper and lower bilateral regulation capabilities will be lost, limiting the ability of the electrochemical energy storage power station to execute primary and secondary frequency regulation instructions, thereby affecting the frequency regulation benefits of the energy storage power station.

[0004] Liquid flow battery energy storage technology has significant advantages in the field of large-scale energy storage due to its large energy capacity, long cycle life and high safety. In frequency modulation applications, liquid flow batteries are frequently charged and discharged, and real-time adjustment of SOC becomes the key to ensure the efficient and safe operation of liquid flow battery energy storage power stations for frequency modulation. Summary of the invention

[0005] In view of the above-mentioned defects in the prior art, the present application provides a method and system for real-time adjustment of SOC of a liquid flow battery energy storage power station for frequency modulation, aiming to solve the problem of real-time adjustment of SOC of a liquid flow battery energy storage power station for frequency modulation.

[0006] In a first aspect, the present application provides a method for real-time adjustment of SOC of a flow battery energy storage power station for frequency modulation, comprising: Obtain the current SOC value and SOC average value of each power unit in the frequency regulation liquid flow battery energy storage power station; Determining whether the current SOC value of each power unit meets the first adjustment condition; If there are multiple first power units whose current SOC values ​​satisfy the first adjustment condition, selecting a first SOC adjustment target value for each first power unit; Determining the charge and discharge priority of each first power unit based on the deviation between the current SOC value of each first power unit and the SOC average value and the selected first SOC adjustment target value; Selecting a first target power unit based on the charge and discharge priority to perform SOC over-limit regulation; The first adjustment condition includes: the current SOC value is greater than or equal to the SOC upper limit value, or the current SOC value is less than or equal to the SOC lower limit value.

[0007] In a second aspect, the present application also provides a real-time SOC adjustment system for a flow battery energy storage power station for frequency modulation, comprising: The first acquisition module is used to obtain the current SOC value and the SOC average value of each power unit in the frequency regulation liquid flow battery energy storage power station; A first judgment module, used to judge whether the current SOC value of each power unit meets the first adjustment condition; A first target value determination module, configured to select a first SOC adjustment target value for each first power unit if there are a plurality of first power units whose current SOC values ​​satisfy a first adjustment condition; A first priority determination module, configured to determine the charge and discharge priority of each first power unit based on a deviation between a current SOC value of each first power unit and an SOC mean value and a selected first SOC adjustment target value; A first selection module, configured to select a first target power unit for SOC over-limit regulation based on a charge and discharge priority; The first adjustment condition includes: the current SOC value is greater than or equal to the SOC upper limit value, or the current SOC value is less than or equal to the SOC lower limit value.

[0008] In a third aspect, the present application also provides an electronic device, comprising: at least one memory for storing programs; and at least one processor for executing the programs stored in the memory. When the program stored in the memory is executed, the processor is used to execute the method described in the first aspect or any possible implementation of the first aspect.

[0009] In a fourth aspect, the present application also provides a computer-readable storage medium, which stores a computer program. When the computer program runs on a processor, the processor executes the method described in the first aspect or any possible implementation of the first aspect.

[0010] In a fifth aspect, the present application further provides a computer program product, which, when executed on a processor, enables the processor to execute the method described in the first aspect or any possible implementation manner of the first aspect.

[0011] The present application provides a method and system for real-time SOC adjustment of a flow battery energy storage power station for frequency regulation. The method and system perform over-limit judgment on the current SOC value of each power unit in the flow battery energy storage power station for frequency regulation, and then use the deviation between the current SOC value and the SOC mean and the first SOC adjustment target value to determine the charge and discharge priority of multiple over-limit first power units, and then select the first target power unit for SOC over-limit adjustment according to the charge and discharge priority. The embodiment of the present application effectively avoids the SOC of the auxiliary frequency regulation or independent frequency regulation flow battery energy storage power station from reaching the charge and discharge limit or cutoff condition through SOC over-limit judgment and SOC real-time adjustment strategy based on SOC over-limit degree and SOC consistency, ensures the execution of frequency regulation instructions, and improves the income of the frequency regulation power station. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the present application or related technologies, the following is a brief introduction to the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0013] Figure 1 This is one of the flow charts of the real-time SOC adjustment method of the frequency modulation liquid flow battery energy storage power station provided in the embodiment of the present application; Figure 2 This is the second flow chart of the real-time SOC adjustment method of the frequency modulation liquid flow battery energy storage power station provided in the embodiment of the present application; Figure 3 is a structural schematic diagram of a SOC real-time adjustment device provided in an embodiment of the present application; Figure 4 This is the third flow chart of the real-time SOC adjustment method of the frequency modulation liquid flow battery energy storage power station provided in the embodiment of the present application; Figure 5 It is a structural schematic diagram of the SOC real-time adjustment system of the frequency modulation liquid flow battery energy storage power station provided in an embodiment of the present application; Figure 6 It is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0015] In the condition where the electrochemical energy storage power station assists the thermal power unit in frequency regulation, the automatic generation control (AGC) task is usually undertaken jointly by the thermal power unit and the electrochemical energy storage power station. The thermal power unit and the electrochemical energy storage power station jointly respond to the AGC command. The energy storage power station balances the grid frequency fluctuations through rapid charging and discharging, while the thermal power unit provides stable basic power. Specifically, the thermal power unit is suitable for slow and large-capacity power regulation tasks, and the energy storage system, with its millisecond response speed and precise power control capability, can quickly make up for the response delay of the thermal power unit and significantly improve the speed and accuracy of frequency regulation. When the charge and discharge SOC of the electrochemical energy storage power station reaches the preset cut-off condition, the energy storage power station will stop the charge and discharge operation. At this time, although the energy storage power station is no longer involved in frequency regulation, the thermal power unit can continue to execute the AGC command to ensure the stability of the grid frequency. However, the withdrawal of the energy storage power station will affect the overall frequency regulation mileage and frequency regulation speed, and reduce the regulation capability of the overall system.

[0016] In the case where the electrochemical energy storage power station participates in the grid frequency regulation as an independent power source, the energy storage power station alone undertakes the AGC task. When the charge and discharge SOC of the energy storage power station reaches its preset upper and lower limits, it will automatically lock and stop responding to further AGC instructions. In the locked state, the energy storage power station cannot adjust automatically and must wait for the reverse charge and discharge instructions from the AGC to resume response. This results in the energy storage power station being unable to respond to further same-direction AGC instructions while waiting for the AGC reverse charge and discharge instructions, making it impossible to achieve continuous frequency regulation. This not only affects the frequency regulation effect, but may also cause the power station to be assessed for failing to complete the frequency regulation task.

[0017] It can be seen that in the conditions where the electrochemical energy storage power station assists the thermal power unit in frequency regulation or participates in the grid frequency regulation as an independent power source, the adjustment of SOC is the key to ensuring the frequency regulation effect. The management of SOC will directly affect the regulation capability of the overall system and the execution effect of AGC instructions.

[0018] Lithium batteries and flow batteries are the two main energy storage technologies for electrochemical energy storage power stations. The power and capacity of lithium batteries are highly coupled and are determined by the internal electrode materials and structure of the battery. Once manufactured, the capacity of the lithium battery cannot be adjusted without destroying the battery structure. During the execution of AGC instructions by the lithium battery energy storage power station, the power unit cannot be switched to other modes, resulting in the inability to adjust the SOC within the station. Considering the rate constraints of lithium batteries, it is usually necessary to configure 1 to 2 hours of energy storage capacity to cope with 3 to 5 minutes of AGC instructions. This configuration significantly increases costs and cannot guarantee 24-hour uninterrupted response for independent energy storage power stations.

[0019] Unlike lithium batteries, the power unit (battery stack) and energy unit (electrolyte storage tank) in the liquid flow battery energy storage unit are physically separated, which can achieve the decoupling of the power unit and the energy unit in the design, operation and control of the energy storage power station, and has broad prospects in the fields of grid black start, transient power support, primary and secondary independent frequency regulation, etc. Compared with the frequency regulation application of lithium battery energy storage power station, the frequency regulation application of liquid flow battery energy storage power station can realize the online real-time adjustment of SOC through independent control of energy units, avoiding the problem of limited frequency regulation capacity caused by SOC reaching the limit or cut-off conditions during the frequency regulation process.

[0020] Based on this, the embodiments of the present application provide a method and system for real-time adjustment of the SOC of a flow battery energy storage power station for frequency regulation, so as to prevent the SOC of an auxiliary frequency regulation or independent frequency regulation power station from reaching charging and discharging limits or cutoff conditions, ensure the execution of frequency regulation instructions, and improve the revenue of the frequency regulation power station.

[0021] In the embodiments of the present application, the flow battery includes but is not limited to an all-vanadium flow battery, a zinc-bromine flow battery, an organic flow battery, an iron-chromium flow battery, and the like.

[0022] Figure 1 This is one of the flow charts of the real-time SOC adjustment method of the frequency modulation liquid flow battery energy storage power station provided in the embodiment of the present application, such as Figure 1 As shown, the method comprises at least the following steps: S101. Obtain the current SOC value and the average SOC value of each power unit in the frequency regulation liquid flow battery energy storage power station.

[0023] Specifically, the current SOC value of each power unit in the frequency regulation liquid flow battery energy storage power station is obtained in real time and the SOC average value of all power units is calculated for subsequent over-limit judgment.

[0024] S102: Determine whether the current SOC value of each power unit meets the first adjustment condition.

[0025] Specifically, the current SOC value of each power unit is judged to be over the limit, and the over limit includes over the upper limit and over the lower limit. The corresponding first adjustment condition includes: the current SOC value is greater than or equal to the SOC upper limit value (discharging operation is required to reduce the SOC value), or the current SOC value is less than or equal to the SOC lower limit value (charging operation is required to increase the SOC value). The SOC upper limit value and the SOC lower limit value correspond to the upper limit and lower limit of the interval of full power operation of the flow battery, respectively.

[0026] Generally speaking, the range of the full-power operation range of the flow battery is smaller than the range of the SOC charge and discharge limit or cutoff condition. For example, the SOC range of the full-power operation range of the all-vanadium flow battery is 30% to 80%, and the SOC range of the SOC charge and discharge limit or cutoff condition is 0% to 100%. In actual operation, the flow battery should work within the full-power operation range as much as possible, while avoiding the SOC charge and discharge limit or cutoff condition to ensure the efficiency and safety of the system. Therefore, using the upper and lower limits of the full-power operation range of the flow battery as the first adjustment condition, the SOC adjustment can be performed in advance before the SOC cutoff condition is reached to avoid touching the SOC charge and discharge limit or cutoff condition.

[0027] S103 . If there are multiple first power units whose current SOC values ​​satisfy the first adjustment condition, select a first SOC adjustment target value for each first power unit.

[0028] Specifically, the first power unit is a power unit whose current SOC value satisfies the first adjustment condition. If the current SOC values ​​of all power units do not meet the first adjustment condition, it means that no power unit is over-limit, and no SOC over-limit adjustment is required. If only one first power unit has a current SOC value that meets the first adjustment condition, then only the SOC over-limit adjustment needs to be performed for this power unit.

[0029] If there are multiple first power units whose current SOC values ​​meet the first adjustment condition, due to the capacity limitation of the energy storage power station and the number limitation of the SOC adjustment device, it is not necessarily possible to adjust the SOC of all the first power units that exceed the limit at the same time in real time, so it is necessary to judge the charging and discharging priority of multiple first power units. In the priority judgment process, it is necessary to measure the degree of deviation between the current SOC value of the first power unit and the first SOC adjustment target value. At the same time, the first power unit may exceed the upper limit or the lower limit, and the corresponding first adjustment target value is also different. Therefore, it is necessary to select the first SOC adjustment target value of each first power unit before the priority judgment.

[0030] The first SOC adjustment target value is often set according to the SOC upper / lower limit value in the limit crossing judgment process, and the SOC upper / lower limit value is often a fixed value, so the first SOC adjustment target value can also be pre-set as a fixed value. In some embodiments, the first SOC adjustment target value of each first power unit is selected in S103, specifically including: If the current SOC value of the first power unit is greater than or equal to the SOC upper limit value, the first SOC adjustment target value is selected as the SOC lower adjustment threshold value; If the current SOC value of the first power unit is less than or equal to the SOC lower limit value, the first SOC adjustment target value is selected as the SOC upper adjustment threshold value.

[0031] Among them, the SOC lower adjustment threshold is less than the SOC upper limit, and the SOC upper adjustment threshold is greater than the SOC lower limit. Generally speaking, the adjustment amount between the SOC lower adjustment threshold and the SOC upper limit is the same as the adjustment amount between the SOC upper adjustment threshold and the SOC lower limit. For example, if the SOC upper limit is 80%, the SOC lower adjustment threshold is set to 75%; if the SOC lower limit is 30%, the SOC upper adjustment threshold is set to 35%.

[0032] S104 : Determine the charge and discharge priority of each first power unit based on the deviation between the current SOC value of each first power unit and the SOC average value and the selected first SOC adjustment target value.

[0033] Specifically, when determining the charge and discharge priority of each first power unit, not only the deviation between the current SOC value of the first power unit and the first SOC adjustment target value is considered, but also the SOC consistency between different power units is considered. The overall charge and discharge priority judgment follows the following principles: the greater the deviation between the current SOC value and the first SOC adjustment target value, the higher the charge and discharge priority; the greater the deviation between the current SOC value and the SOC mean, the higher the charge and discharge priority.

[0034] In some embodiments, the charge and discharge priorities of the first power units are determined in S104, specifically satisfying the following formula 1: ; in, Indicates i The charging and discharging priority of the first power unit, The larger the value, the higher the charge and discharge priority; Indicates i A current SOC value of a first power unit; represents a first SOC adjustment target value, and the first SOC adjustment target values ​​corresponding to different first power units may be different, and may specifically be an SOC upper adjustment threshold or an SOC lower adjustment threshold; Indicates the mean SOC value. 10% is the preset maximum deviation of SOC consistency of different power units that the system can accept. It can be set according to actual needs. and They represent the adjustable weight coefficients, representing the SOC limit degree and SOC consistency for the priority of charging and discharging. The contribution level meets In the actual implementation process, you can adjust and To achieve the focus on SOC limit degree and SOC consistency, for example, pay more attention to SOC limit regulation rather than consistency regulation, set , .

[0035] S105 . Select a first target power unit based on the charge and discharge priority to perform SOC over-limit regulation.

[0036] Specifically, one or more first power units with the highest charge and discharge priority are selected for SOC over-limit adjustment according to the ascending or descending order of charge and discharge priority. The one or more first power units selected in the SOC over-limit judgment are the first target power units. The target or cutoff condition of SOC over-limit adjustment is to reach the first SOC adjustment target value corresponding to the power unit.

[0037] The SOC real-time adjustment method of the liquid flow battery energy storage power station for frequency regulation provided in the embodiment of the present application is to judge the current SOC value of each power unit in the liquid flow battery energy storage power station for frequency regulation by over-limit judgment, and then use the deviation between the current SOC value and the SOC mean value and the first SOC adjustment target value to determine the charge and discharge priority of multiple over-limit first power units, and then select the first target power unit for SOC over-limit adjustment according to the charge and discharge priority. The embodiment of the present application effectively avoids the SOC of the auxiliary frequency regulation or independent frequency regulation liquid flow battery energy storage power station from reaching the charge and discharge limit or cut-off condition through SOC over-limit judgment and SOC real-time adjustment strategy based on SOC over-limit degree and SOC consistency, ensures the execution of frequency regulation instructions, and improves the income of the frequency regulation power station.

[0038] Furthermore, in addition to SOC over-limit regulation to prevent the SOC from reaching the charge and discharge limit or cut-off condition, SOC economic regulation is also performed to further reduce the operating cost of the energy storage power station.

[0039] Figure 2 This is the second flow chart of the real-time SOC adjustment method of the frequency modulation liquid flow battery energy storage power station provided in the embodiment of the present application, such as Figure 2 As shown, the method comprises at least the following steps: S201. Obtain the predicted grid frequency mean and predicted average electricity price for the current period.

[0040] Specifically, SOC economic regulation is based on the prediction of electricity prices and grid frequency, and subsequent charging and discharging adjustments are made according to the prediction results.

[0041] Update the predicted grid frequency mean at fixed time intervals , the predicted grid frequency mean It is calculated by the predicted grid frequency curve between the current update time and the next update time. The current frequency-regulated power station is generally configured at full power for 2 hours, so the grid frequency curve within the next 2 hours can be predicted every 2 hours, and the predicted grid frequency mean can be calculated according to the predicted grid frequency curve. .

[0042] Update the predicted average electricity price at regular intervals , the predicted average electricity price It is calculated by the predicted electricity price curve between the current update time and the next update time. For example, the electricity price curve for the next 24 hours is predicted every 24 hours, and the predicted average electricity price is calculated according to the predicted electricity price curve. .

[0043] S202: Determine whether the predicted grid frequency mean and the predicted average electricity price meet the second adjustment condition.

[0044] Specifically, the possible situations between the predicted grid frequency mean and the grid standard frequency, and between the predicted average electricity price and the current electricity price are: The predicted average grid frequency is higher than the standard grid frequency, and the predicted average electricity price is higher than the current electricity price. In this case, no SOC adjustment is required. The predicted average grid frequency is higher than the grid standard frequency, and the predicted average electricity price is lower than the current electricity price, indicating that the grid will discharge to the energy storage power station to reduce the frequency in the future. The energy storage power station will need to be charged accordingly. Therefore, the energy storage power station is discharged in advance to reserve the capacity for frequency reduction. The predicted average grid frequency is lower than the grid standard frequency, and the predicted average electricity price is higher than the current electricity price, indicating that the grid will charge the energy storage power station to increase the frequency in the future. The energy storage power station will need to discharge accordingly. Therefore, the energy storage power station is charged in advance to reserve the capacity for frequency increase. The predicted average grid frequency is lower than the standard grid frequency, and the predicted average electricity price is lower than the current electricity price. At this time, there is no need to adjust the SOC.

[0045] From this, it can be seen that the second adjustment includes: predicting the average grid frequency is higher than the grid standard frequency and the predicted average electricity price is lower than the current electricity price, or predicting the average grid frequency is lower than the grid standard frequency and the predicted average electricity price is higher than the current electricity price.

[0046] S203: If the second adjustment condition is met, determine a second SOC adjustment target value based on the predicted grid frequency mean and the predicted average electricity price.

[0047] Specifically, during the SOC economy adjustment process, the SOC adjustment target value is no longer a fixed optional value set based on the SOC upper / lower limit value, but is related to the real-time predicted grid frequency mean and predicted average electricity price. After the initial judgment of the second adjustment condition on the predicted grid frequency mean and predicted average electricity price, the second SOC adjustment value needs to be calculated in real time.

[0048] In some embodiments, determining the second SOC adjustment target value in S203 includes: Based on the deviation between the predicted average electricity price and the current electricity price, a first frequency regulation capacity offset is determined; based on the deviation between the predicted grid frequency mean and the grid standard frequency, a second frequency regulation capacity offset is determined; Based on the median value of the full power operation range of the flow battery, combined with the first frequency modulation capacity offset and the second frequency modulation capacity offset, a second SOC adjustment target value is determined.

[0049] Specifically, the second SOC adjustment target value is a cutoff condition for SOC economic adjustment, and the purpose of performing SOC over-limit adjustment based on the second SOC adjustment target value is to reserve frequency adjustment capacity.

[0050] The specific calculation process of the second SOC adjustment target value is as follows: First, the first frequency regulation capacity offset is calculated based on the deviation between the predicted mean electricity price and the current electricity price, and the second frequency regulation capacity offset is calculated based on the deviation between the predicted mean grid frequency and the mean grid standard frequency. The first frequency regulation capacity offset represents the influence of electricity price on the second SOC adjustment target value, and the second frequency regulation capacity offset represents the influence of grid frequency on the second SOC adjustment target value; then, the second SOC adjustment target value is calculated by combining the first frequency regulation capacity offset, the second frequency regulation capacity offset and the median of the full power operation range of the flow battery.

[0051] It should be noted that the above calculation process can be implemented through a calculation formula in the actual execution process, and it is not necessary to strictly execute the process of first calculating the frequency modulation capacity offset and then calculating the second SOC adjustment target value.

[0052] In some embodiments, when the predicted grid frequency average is higher than the grid standard frequency and the predicted average electricity price is lower than the current electricity price, the second SOC adjustment target value is determined to satisfy the following formula 2: ( , ).

[0053] When the predicted grid frequency average is lower than the grid standard frequency and the predicted average electricity price is higher than the current electricity price, the second SOC adjustment target value is determined to satisfy the following formula 3: ( , ).

[0054] In formula 2 and formula 3, represents a second SOC adjustment target value; It represents the median value of the full power operating range of the flow battery. Taking the full power operating range of the flow battery as 30% to 80% as an example, The value is 55%; represents the predicted mean grid frequency, Indicates the standard frequency of the power grid, generally 50Hz; represents the predicted average electricity price, Indicates the current electricity price; and They represent the first frequency modulation capacity offset and the second frequency modulation capacity offset respectively.

[0055] Satisfies the following formula 4: ; in, represents the rounding function, Indicates the maximum impact of electricity price on the second SOC adjustment target value. In actual implementation, It is generally set to an integer between 0 and 25, that is, the maximum impact of electricity price on the second SOC adjustment target value cannot exceed 25%, otherwise the second adjustment target value will exceed the SOC upper limit value of 80%.

[0056] Satisfies the following formula 5: .

[0057] in, represents the rounding function, Indicates the maximum deviation value of the power grid frequency, Indicates the maximum impact of the grid frequency on the second SOC adjustment target value. In actual implementation, the maximum grid frequency deviation value It is usually set to 0.2, and the small power grid system is set to 0.5; It is usually set to an integer between 0 and 25 and satisfies .

[0058] It can be seen from the above formula that the second SOC adjustment target value fluctuates based on the median of the full-power operating range of the flow battery. This can ensure to the greatest extent that the SOC values ​​of all power units after adjustment are still within the full-power operating range of the flow battery and will not touch the charging and discharging restrictions or cut-off conditions.

[0059] S204: Determine whether the current SOC value of each power unit meets a third adjustment condition based on the determined second SOC adjustment target value.

[0060] Specifically, the priority of SOC economic regulation is generally lower than SOC over-limit regulation, that is, SOC economic regulation is only considered to be triggered when it is determined that the current SOC values ​​of all power units in the frequency-modulation liquid flow battery energy storage power station do not meet the first regulation condition. Therefore, in the process of SOC economic regulation, after initially judging that SOC economic regulation is required through the second regulation condition, the calculated second SOC regulation target value is used as the basis for over-limit judgment to determine the power unit that needs SOC over-limit regulation.

[0061] When the predicted grid frequency average is higher than the grid standard frequency and the predicted average electricity price is lower than the current electricity price, the second SOC adjustment target value is lower than the median of the full power operation range of the flow battery, and if the current SOC value of the power unit is greater than the second SOC adjustment target value, discharge is required. The third adjustment condition includes: the current SOC value is greater than the second SOC adjustment target value.

[0062] When the predicted grid frequency average is lower than the grid standard frequency and the predicted average electricity price is higher than the current electricity price, the second SOC adjustment target value is higher than the median of the full power operation range of the flow battery, and if the current SOC value of the power unit is less than the second SOC adjustment target value, charging is required. The third adjustment condition includes: the current SOC value is less than the second adjustment target value.

[0063] S205: If there are multiple second power units whose current SOC values ​​satisfy the third adjustment condition, determine the charging and discharging priority of the second power units based on the deviation between the current SOC value and the second SOC adjustment target value and the SOC average value.

[0064] Specifically, the second power unit is a power unit whose current SOC value satisfies the third adjustment condition. If the current SOC values ​​of all power units do not meet the third adjustment condition, it means that there is no need to perform SOC over-limit adjustment. If only one power unit has a current SOC value that meets the third adjustment condition, then only the SOC over-limit adjustment needs to be performed for the power unit.

[0065] If there are multiple second power units whose current SOC values ​​meet the third adjustment condition, due to the capacity limitation of the energy storage power station and the limitation on the number of SOC adjustment devices, it is not necessarily possible to perform real-time SOC adjustment on all the second power units that exceed the limit at the same time. Therefore, it is necessary to judge the charging and discharging priority of the multiple second power units.

[0066] When determining the charge and discharge priority of each second power unit during the SOC economy adjustment process, the deviation between the current SOC value of the second power unit and the second SOC adjustment target value, as well as the SOC consistency between different power units, are also taken into account. The overall charge and discharge priority judgment follows the following principles: the greater the deviation between the current SOC value and the second SOC adjustment target value, the higher the charge and discharge priority; the greater the deviation between the current SOC value and the SOC mean, the higher the charge and discharge priority.

[0067] In some embodiments, the charge and discharge priority of the second power unit determined in S205 satisfies the following formula: ; in, Indicates i The charging and discharging priority of the second power unit, The larger the value, the higher the charge and discharge priority; Indicates i a current SOC value of a second power unit; represents a second SOC adjustment target value, and the second SOC adjustment target values ​​corresponding to different second power units are the same; represents the mean SOC; and They represent the adjustable weight coefficients, representing the SOC limit degree and SOC consistency for the priority of charging and discharging. degree of contribution.

[0068] That is, the same formula is used to calculate the charge and discharge priority in the SOC economic regulation and SOC over-limit regulation process. The difference is that in the SOC economic regulation process, the second SOC regulation target values ​​of different second power units are the same. It should be noted that in the SOC over-limit regulation and SOC economic regulation process, the charge and discharge priority formula and The value can be set differently according to actual needs.

[0069] S206 : Select a second target power unit based on the charge and discharge priority to perform SOC over-limit adjustment.

[0070] Specifically, one or more second power units with the highest charge and discharge priority are selected for SOC over-limit adjustment according to the ascending or descending order of charge and discharge priority. The one or more second power units selected in the SOC over-limit judgment are the second target power units. The target or cutoff condition of SOC over-limit adjustment during SOC economic adjustment is to reach the second SOC adjustment target value, or the current electricity price reaches the predicted average electricity price.

[0071] The real-time SOC adjustment method for a flow battery energy storage power station for frequency regulation provided in the embodiment of the present application, on the basis of avoiding the SOC from reaching the charge and discharge limit or cut-off condition through the SOC over-limit condition, further considers the economy of the flow battery energy storage power station for frequency regulation, calculates the second SOC adjustment target value by predicting the mean value of the grid frequency and the predicted average electricity price, and uses the second SOC adjustment target value to further perform SOC over-limit adjustment, thereby further enhancing the stability of the grid frequency, optimizing the operation strategy of the energy storage power station, and reducing the operation cost of the energy storage power station.

[0072] Furthermore, considering the physical separation of the power unit and the energy unit of the flow battery, the SOC over-limit regulation of the target power unit is realized by externally connecting an SOC real-time regulation device to the energy unit of the target power unit. The SOC real-time regulation device at least includes: a battery stack, a charger and a circulation loop, the circulation loop connects the battery stack and the energy unit, and the charger and the circulation loop are connected.

[0073] Figure 3 is a structural diagram of the SOC real-time adjustment device provided in an embodiment of the present application, such as Figure 3 As shown, the SOC real-time adjustment device includes: a battery stack, a charging and discharging machine and a circulation loop.

[0074] The energy unit of the target power unit includes a positive electrode storage tank and a negative electrode storage tank.

[0075] Battery stack: A small liquid flow battery stack composed of graphite bipolar plates and ion exchange membranes. The bidirectional current provided by the charger and discharger drives the electrolyte redox reaction and directly regulates the electrolyte valence state.

[0076] Circulation loop: It includes the positive main loop connecting the battery stack and the positive electrode storage tank, and the negative main loop connecting the battery stack and the negative electrode storage tank. The top and bottom of the flow battery storage tank are respectively provided with SOC adjustment backup interfaces, and each interface is extended to the outside of the storage tank through an acid-resistant hose (with a quick-connect interface matching the SOC real-time adjustment device at the end) to facilitate the access of the SOC real-time adjustment device. Pumps and flow meters are provided on both the positive and negative main loops. The pump is used to transport electrolyte. The pump drives the electrolyte to flow out of the storage tank - through the battery stack reaction - back to the storage tank. The flow meter is used to monitor and feedback flow data in real time.

[0077] Charger and Discharger: Provides controllable current to the battery stack and realizes SOC up / down regulation by switching the current direction. It is connected to the positive main circuit through the positive branch circuit and to the negative main circuit through the negative branch circuit.

[0078] It is conceivable that the access of the SOC real-time adjustment device can be achieved through automated means, or manually. For the access of the SOC real-time adjustment device through automated means, it can be achieved by issuing SOC real-time adjustment instructions to control the on-off of the pipeline between the liquid storage tank backup interface and the SOC real-time adjustment device interface.

[0079] Optionally, the SOC real-time adjustment device is configured as a movable independent device, equipped with an electric crawler or track moving mechanism to achieve rapid access to energy units corresponding to different power units.

[0080] Optionally, the SOC real-time adjustment device is powered directly by the energy storage power station power system.

[0081] The technical solution provided in the embodiments of the present application is further illustrated by two specific examples below.

[0082] Assume that there is a small frequency-modulated liquid flow battery energy storage power station, configured as 2MW / 4MWh, including 4 energy storage units, each of which is configured as 500KW / 1MWh, and equipped with a 50KW SOC real-time adjustment device. The full power operating range of the liquid flow battery is 30%-80%.

[0083] Figure 4 This is the third flow chart of the real-time SOC adjustment method for the frequency modulation liquid flow battery energy storage power station provided in the embodiment of the present application, referring to Figure 4 , give priority to SOC over-limit adjustment: Assume that the current SOC values ​​of each power unit are 0.27, 0.29, 0.34, and 0.35, respectively, and the average SOC value is: .

[0084] Step a: SOC over-limit judgment: Power units 1 and 2 meet the first adjustment condition: .

[0085] Step b: Select the first SOC adjustment target value as 35%.

[0086] Step c: Calculate the charging and discharging priority: Calculate the charging priority of power units 1 and 2 (When calculating, priority is given to whether the SOC exceeds the limit, so α=0.7, β=0.3): ; .

[0087] Step d: Select the first target power unit to perform SOC over-limit adjustment: Therefore, power unit 1 is charged first and the charging stops when the SOC value reaches 0.35.

[0088] When the current SOC value of each power unit is between 30% and 80%, SOC economic adjustment is performed: Assume that the current SOC values ​​of each power unit are 0.42, 0.38, 0.44, and 0.46, respectively, and predict the average electricity price in the next 24 hours. The current electricity price is 2 yuan / Wh. 1.2 yuan / Wh, and the average grid frequency for the next 2 hours is predicted is 49.85Hz; the economic operation strategy of the energy storage power station is to reserve capacity for frequency regulation first, and the maximum impact of electricity price and frequency on SOC does not exceed 10%, that is, λ=β=10; The frequency deviation limit of 0.2 under normal operating conditions of the power system specified in the national standard GB / T 15945-2008 is taken.

[0089] Step a, SOC economic adjustment trigger judgment: the current electricity price is lower than the predicted average electricity price, and the predicted frequency is low, and the second adjustment condition is met to trigger SOC economic adjustment.

[0090] Step b: Determine a second SOC adjustment target value.

[0091] First calculate and : ; .

[0092] Calculate the second SOC adjustment target value: .

[0093] Step c: SOC over-limit judgment: the current SOC values ​​of all power units are less than 66%.

[0094] Step d: Calculate the charging and discharging priority: Calculate the charging priority of all power units (Set α=0.5, β=0.5): ; ; ; .

[0095] Step e: Select the second target power unit to perform SOC over-limit adjustment: Therefore, the No. 2 power unit is charged first until the SOC value is 0.66 or the electricity price is higher than the average electricity price.

[0096] The SOC real-time adjustment system of the liquid flow battery energy storage power station for frequency modulation provided in the present application is described below. The SOC real-time adjustment system of the liquid flow battery energy storage power station for frequency modulation described below and the SOC real-time adjustment method of the liquid flow battery energy storage power station for frequency modulation described above can be referred to each other.

[0097] Figure 5 : is a structural schematic diagram of the SOC real-time adjustment system of the frequency modulation liquid flow battery energy storage power station provided in the embodiment of the present application, such as Figure 5 As shown, the device at least includes: The first acquisition module 501 is used to obtain the current SOC value and the SOC mean value of each power unit in the frequency regulation liquid flow battery energy storage power station; A first judgment module 502 is used to judge whether the current SOC value of each power unit meets the first adjustment condition; A first target value determination module 503, configured to select a first SOC adjustment target value for each first power unit if there are multiple first power units whose current SOC values ​​satisfy the first adjustment condition; A first priority determination module 504, configured to determine the charge and discharge priority of each first power unit based on a deviation between a current SOC value of each first power unit and an SOC mean value and a selected first SOC adjustment target value; A first selection module 505, configured to select a first target power unit for SOC over-limit regulation based on the charge and discharge priority; The first adjustment condition includes: the current SOC value is greater than or equal to the SOC upper limit value, or the current SOC value is less than or equal to the SOC lower limit value.

[0098] In some embodiments, the first target value determination module 503 is specifically used to: If the current SOC value of the first power unit is greater than or equal to the SOC upper limit value, the first SOC adjustment target value is selected as the SOC lower adjustment threshold value; If the current SOC value of the first power unit is less than or equal to the SOC lower limit value, the first SOC adjustment target value is selected as the SOC upper adjustment threshold value; Among them, the SOC lower adjustment threshold is less than the SOC upper limit value, and the SOC upper adjustment threshold is greater than the SOC lower limit value.

[0099] In some embodiments, the apparatus further comprises: The second acquisition module is used to obtain the predicted grid frequency mean and predicted average electricity price for the current period; A second judgment module is used to judge whether the predicted grid frequency mean and the predicted average electricity price meet the second adjustment condition; A second target value determination module, configured to determine a second SOC adjustment target value based on a predicted grid frequency mean and a predicted average electricity price if a second adjustment condition is met; a third judgment module, configured to judge whether a current SOC value of each power unit satisfies a third adjustment condition based on the determined second SOC adjustment target value; a second priority determination module, configured to determine the charge and discharge priority of the second power unit based on a deviation between the current SOC value and the second SOC adjustment target value and the SOC mean value if there are a plurality of second power units whose current SOC values ​​satisfy the third adjustment condition; A second selection module, configured to select a second target power unit for SOC over-limit adjustment based on the charge and discharge priority; Among them, the second adjustment condition includes: the predicted average grid frequency is higher than the grid standard frequency and the predicted average electricity price is lower than the current electricity price, or the predicted average grid frequency is lower than the grid standard frequency and the predicted average electricity price is higher than the current electricity price.

[0100] In some embodiments, the second target value determination module is specifically used to: Based on the deviation between the predicted average electricity price and the current electricity price, a first frequency regulation capacity offset is determined; based on the deviation between the predicted grid frequency mean and the grid standard frequency, a second frequency regulation capacity offset is determined; Based on the median value of the full power operation range of the flow battery, combined with the first frequency modulation capacity offset and the second frequency modulation capacity offset, a second SOC adjustment target value is determined.

[0101] In some embodiments, when the predicted grid frequency average is higher than the grid standard frequency and the predicted average electricity price is lower than the current electricity price, the second SOC adjustment target value is determined to satisfy: ( , ); When the predicted grid frequency mean is lower than the grid standard frequency and the predicted average electricity price is higher than the current electricity price, the second SOC adjustment target value is determined to meet the following conditions: ( , ); in, represents the second SOC adjustment target value, represents the median value of the full power operating range of the flow battery, represents the predicted mean grid frequency, Indicates the standard frequency of the power grid, represents the predicted average electricity price, represents the current electricity price, and They respectively represent the influence of electricity price and grid frequency on the second SOC adjustment target value, satisfying: ; ; in, represents the rounding function, Indicates the maximum deviation value of the power grid frequency, and They respectively represent the maximum impact of electricity price and grid frequency on the second SOC adjustment target value.

[0102] In some embodiments, the charge and discharge priority satisfies the following formula: ; in, Indicates i The charging and discharging priority of each power unit, Indicates i The current SOC value of each power unit, Indicates the SOC adjustment target value, represents the mean SOC value, and Respectively represent adjustable weight coefficients.

[0103] It can be understood that the detailed functional implementation of each of the above-mentioned units / modules can be found in the introduction of the aforementioned method embodiment, and will not be repeated here.

[0104] It should be understood that the above-mentioned system is used to execute the methods in the above-mentioned embodiments. The implementation principles and technical effects of the corresponding program modules in the system are similar to those described in the above-mentioned methods. The working process of the system can refer to the corresponding process in the above-mentioned method and will not be repeated here.

[0105] Based on the method in the above embodiment, an embodiment of the present application provides an electronic device. The device may include: at least one memory for storing programs and at least one processor for executing the programs stored in the memory. When the program stored in the memory is executed, the processor is used to execute the method described in the above embodiment.

[0106] Figure 6 is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application, such as Figure 6As shown, the electronic device may include: a processor (Processor) 601, a communication interface (Communications Interface) 602, a memory (Memory) 603 and a communication bus 604, wherein the processor 601, the communication interface 602, and the memory 603 communicate with each other through the communication bus 604. The processor 601 can call the software instructions in the memory 603 to execute the method described in the above embodiment.

[0107] In addition, the logic instructions in the above-mentioned memory 603 can be implemented in the form of software functional units and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present application.

[0108] Based on the method in the above embodiment, an embodiment of the present application provides a computer-readable storage medium, which stores a computer program. When the computer program runs on a processor, the processor executes the method in the above embodiment.

[0109] Based on the method in the above embodiment, an embodiment of the present application provides a computer program product. When the computer program product runs on a processor, the processor executes the method in the above embodiment.

[0110] It is understandable that the processor in the embodiment of the present application may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, transistor logic devices, hardware components or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0111] The method steps in the embodiments of the present application can be implemented by hardware or by a processor executing software instructions. The software instructions can be composed of corresponding software modules, and the software modules can be stored in random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, mobile hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can be located in an ASIC.

[0112] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented by software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted through the computer-readable storage medium. The computer instructions may be transmitted from a website site, computer, server or data center to another website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)), etc.

[0113] It should be understood that the various numerical numbers involved in the embodiments of the present application are only used for the convenience of description and are not used to limit the scope of the embodiments of the present application.

[0114] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for real-time SOC adjustment of a flow battery energy storage power station for frequency modulation, characterized in that: include: Obtain the current SOC value and SOC average value of each power unit in the frequency regulation liquid flow battery energy storage power station; Determining whether the current SOC value of each power unit meets the first adjustment condition; If there are multiple first power units whose current SOC values ​​satisfy the first adjustment condition, selecting a first SOC adjustment target value for each first power unit; Determining the charge and discharge priority of each first power unit based on the deviation between the current SOC value of each first power unit and the SOC mean value and the selected first SOC adjustment target value; Selecting a first target power unit based on the charge and discharge priority to perform SOC over-limit regulation; The first adjustment condition includes: the current SOC value is greater than or equal to the SOC upper limit value, or the current SOC value is less than or equal to the SOC lower limit value.

2. The method for real-time SOC adjustment of a frequency modulation liquid flow battery energy storage power station according to claim 1, characterized in that: The selecting the first SOC adjustment target value of each first power unit includes: If the current SOC value of the first power unit is greater than or equal to the SOC upper limit value, selecting the first SOC adjustment target value as the SOC lower adjustment threshold; If the current SOC value of the first power unit is less than or equal to the SOC lower limit value, selecting the first SOC adjustment target value as the SOC upper adjustment threshold value; The SOC lower adjustment threshold is smaller than the SOC upper limit value, and the SOC upper adjustment threshold is larger than the SOC lower limit value.

3. The method for real-time SOC adjustment of a flow battery energy storage power station for frequency modulation according to claim 1, characterized in that: The method further comprises: Obtain the predicted grid frequency mean and predicted average electricity price for the current period; Determining whether the predicted grid frequency mean and the predicted average electricity price meet a second adjustment condition; If the second adjustment condition is met, determining a second SOC adjustment target value based on the predicted grid frequency mean and the predicted average electricity price; determining whether a current SOC value of each power unit meets a third adjustment condition based on the determined second SOC adjustment target value; If there are multiple second power units whose current SOC values ​​satisfy the third adjustment condition, determining the charging and discharging priority of the second power unit based on the deviation between the current SOC value and the second SOC adjustment target value and the SOC mean value; Selecting a second target power unit based on the charge and discharge priority to perform SOC over-limit regulation; Among them, the second adjustment condition includes: the predicted average grid frequency is higher than the grid standard frequency and the predicted average electricity price is lower than the current electricity price, or the predicted average grid frequency is lower than the grid standard frequency and the predicted average electricity price is higher than the current electricity price.

4. The method for real-time SOC adjustment of a flow battery energy storage power station for frequency modulation according to claim 3 is characterized in that: The determining of the second SOC adjustment target value includes: Based on the deviation between the predicted average electricity price and the current electricity price, a first frequency regulation capacity offset is determined; based on the deviation between the predicted grid frequency mean and the grid standard frequency, a second frequency regulation capacity offset is determined; The second SOC adjustment target value is determined based on the median value of the full power operation range of the flow battery in combination with the first frequency modulation capacity offset and the second frequency modulation capacity offset.

5. The method for real-time SOC adjustment of a frequency modulation liquid flow battery energy storage power station according to claim 4, characterized in that: When the predicted grid frequency average is higher than the grid standard frequency and the predicted average electricity price is lower than the current electricity price, the second SOC adjustment target value is determined to meet the following conditions: （ , ）； When the predicted grid frequency mean is lower than the grid standard frequency and the predicted average electricity price is higher than the current electricity price, the second SOC adjustment target value is determined to meet the following conditions: （ ， ）； in, represents the second SOC adjustment target value, represents the median value of the full power operating range of the flow battery, represents the predicted mean grid frequency, Indicates the standard frequency of the power grid, represents the predicted average electricity price, represents the current electricity price, and represent the first frequency modulation capacity offset and the second frequency modulation capacity offset respectively, satisfying: ； ； in, represents the rounding function, Indicates the maximum deviation value of the power grid frequency, and They respectively represent the maximum impact of electricity price and grid frequency on the second SOC adjustment target value.

6. The method for real-time SOC adjustment of a frequency modulation liquid flow battery energy storage power station according to claim 1 or 3, characterized in that: The charging and discharging priority satisfies the following formula: ； in, Indicates i The charging and discharging priority of each power unit, Indicates i The current SOC value of each power unit, Indicates the SOC adjustment target value, represents the mean SOC value, and Respectively represent adjustable weight coefficients.

7. The method for real-time SOC adjustment of a frequency modulation liquid flow battery energy storage power station according to claim 1 or 3, characterized in that: The over-limit regulation is achieved by connecting an SOC real-time regulation device to an energy unit corresponding to the target power unit.

8. The method for real-time SOC adjustment of a frequency modulation liquid flow battery energy storage power station according to claim 7, characterized in that: The SOC real-time adjustment device includes a battery stack, a charger and a discharger, and a circulation loop. The circulation loop connects the battery stack and the energy unit, and the charger and the discharger is connected to the circulation loop.

9. A real-time SOC adjustment system for a flow battery energy storage power station for frequency modulation, characterized in that: include: The first acquisition module is used to obtain the current SOC value and the SOC average value of each power unit in the frequency regulation liquid flow battery energy storage power station; A first judgment module, used to judge whether the current SOC value of each power unit meets the first adjustment condition; A first target value determination module, configured to select a first SOC adjustment target value for each first power unit if there are multiple first power units whose current SOC values ​​satisfy the first adjustment condition; A first priority determination module, configured to determine the charge and discharge priority of each first power unit based on a deviation between a current SOC value of each first power unit and the SOC mean value and a selected first SOC adjustment target value; A first selection module, configured to select a first target power unit for SOC over-limit regulation based on a charge and discharge priority; The first adjustment condition includes: the current SOC value is greater than or equal to the SOC upper limit value, or the current SOC value is less than or equal to the SOC lower limit value.

10. An electronic device, characterized in that: include: at least one memory for storing a computer program; At least one processor is used to execute the program stored in the memory. When the program stored in the memory is executed, the processor is used to execute the method according to any one of claims 1 to 8.

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