Energy storage system SOC correction method, device, processor and storage medium applied to flywheel frequency modulation system

Abstract

The present invention relates to the technical field of SOC correction, and specifically discloses a method, device, processor and storage medium for SOC correction of an energy storage system applied to a flywheel frequency modulation system. The method includes: determining whether a preset fast SOC correction condition is currently satisfied; if the preset fast SOC correction condition is satisfied, obtaining an estimated SOC value of the energy storage system; determining whether the estimated SOC value is within a fast correction interval; if the estimated SOC value is within the fast correction interval, performing a fast correction operation; if the estimated SOC value is less than the fast correction interval, performing a low power SOC correction operation; if the estimated SOC value is greater than the fast correction interval, performing a high power SOC correction operation. By utilizing the actual physical characteristics of lithium iron phosphate batteries during use, precise SOC correction is performed on the middle and end of their use, thereby improving the monitoring accuracy of the battery capacity of the energy storage system, improving the SOC monitoring accuracy, meeting the business requirements of specific scenarios, and meeting the actual needs of enterprises.

Description

Technical Field

[0001] The present invention relates to the technical field of SOC correction, and in particular to a method for correcting the SOC of an energy storage system applied to a flywheel frequency modulation system, an apparatus for correcting the SOC of an energy storage system applied to a flywheel frequency modulation system, a processor, and a computer-readable storage medium. Background Art

[0002] With the continuous development of new energy technologies, the access of new energy to the power grid has affected the power grid. To solve this technical problem, technicians use an energy storage system to store and buffer the electric energy generated by new energy, such as using a flywheel for energy conversion.

[0003] In the traditional on-vehicle new energy control field, since the operating conditions are relatively stable and the charging and discharging are managed by the on-vehicle controller, the electric energy management is relatively simple and accurate. However, when applied to a flywheel system, due to the large randomness of the flywheel operation and the uncontrollability of charging and discharging at any time, it is required that the battery system can effectively operate in the 50% - 80% interval of the SOC. Therefore, the existing energy storage system faces at least the following technical problems in the management process:

[0004] On the one hand, in the field of power batteries, due to the weak linear characterization of the open-circuit voltage of lithium iron phosphate battery cells and the existence of a plateau period, there are certain deviations in the correction of the SOC. And in the flywheel frequency modulation system, there are occasional large current inputs / outputs. If the electric energy of the energy storage system is at the critical value of the plateau period at this time, the energy storage system cannot respond to the large current inputs / outputs of the flywheel frequency modulation system, thus unable to meet the actual use requirements.

[0005] On the second hand, compared with the conventional power consumption scenarios where full charge or full discharge can be achieved, the energy storage system lacks the opportunity for end correction when used in the above application scenarios. Therefore, it is impossible to ensure the correction requirements and accuracy in the 50% - 80% interval, and it is impossible to effectively evaluate and monitor the capacity in this interval.

[0006] On the other hand, when using a semi-solid or solid-state battery system, large current charging and discharging are allowed. At this time, the current change increases, and the large current operating conditions will cause abnormal effects on the voltage, further resulting in large deviations in the SOC estimation. Therefore, the existing SOC correction methods cannot meet the actual requirements. Summary of the Invention

[0007] To overcome the above technical problems existing in the prior art, an embodiment of the present invention provides a method, device, processor, and storage medium for SOC correction of an energy storage system applied to a flywheel frequency modulation system. By utilizing the actual physical characteristics of a lithium iron phosphate battery during use, precise SOC correction is performed in the middle and end of its use, thereby improving the monitoring accuracy of the battery capacity of the energy storage system, improving the SOC monitoring accuracy, meeting the business requirements of specific scenarios, and satisfying the actual needs of enterprises.

[0008] To achieve the above object, an embodiment of the present invention provides a method for SOC correction of an energy storage system applied to a flywheel frequency modulation system, the method including: determining whether a preset fast SOC correction condition is currently satisfied; if the preset fast SOC correction condition is satisfied, obtaining an estimated SOC value of the energy storage system; determining whether the estimated SOC value is located in a fast correction interval, the fast correction interval being located in the plateau region of the OCV curve of the energy storage system; if the estimated SOC value is located in the fast correction interval, performing a fast correction operation; if the estimated SOC value is less than the fast correction interval, performing a low-power SOC correction operation; if the estimated SOC value is greater than the fast correction interval, performing a high-power SOC correction operation.

[0009] Preferably, the performing the fast correction operation includes: obtaining a fast OCV table; obtaining the current voltage value of the energy storage system; determining an actual SOC value from the fast OCV table based on the current voltage value; determining whether the deviation between the actual SOC value and the estimated SOC value is greater than a deviation threshold; if so, replacing the estimated SOC value with the actual SOC value.

[0010] Preferably, the obtaining the fast OCV table includes: determining a step range of the plateau region in the OCV curve of the energy storage system; performing multiple discharge processes on the energy storage system within the step range to obtain first voltage data of the energy storage system at a unit OCV value, generating a discharge OCV table based on the first voltage data; performing multiple charge processes on the energy storage system within the step range to obtain second voltage data of the energy storage system at a unit OCV value, generating a charge OCV table based on the second voltage data; generating a fast OCV table based on the discharge OCV table and the charge OCV table.

[0011] Preferably, the execution of the low - power SOC correction operation includes: determining whether there is a low - voltage single - cell battery in the energy storage system with a voltage value less than a preset empty - battery voltage; if there is such a low - voltage single - cell battery, obtaining the prior usage state of the energy storage system; in the case where the prior usage state is static discharge, obtaining the first duration for which the energy storage system is in a static state, and performing static SOC correction processing based on the first duration; in the case where the prior usage state is a large - current discharge state, obtaining the second duration for which the energy storage system is in the large - current discharge state, where the first duration is greater than the second duration, and performing dynamic SOC correction processing based on the second duration.

[0012] Preferably, the performing of the static SOC correction processing based on the first duration includes: determining whether the first duration reaches a first time threshold; if the first duration reaches the first time threshold, assigning the estimated SOC value to zero; the performing of the dynamic SOC correction processing based on the second duration includes: determining whether the second duration reaches a second time threshold; if the second duration reaches the second time threshold, determining whether the estimated SOC value is greater than a preset SOC limit value, and if the estimated SOC value is greater than the preset SOC limit value, replacing the estimated SOC value with the preset SOC limit value.

[0013] Preferably, the method further includes: initializing the available energy value of the energy storage system; real - time obtaining the operating voltage and operating current of the energy storage system, and adjusting the available energy value based on the operating voltage and the operating current; if the estimated SOC value is less than the preset SOC limit value, determining whether the adjusted available energy value is zero: if the adjusted available energy value is zero, assigning the estimated SOC value to zero; if the adjusted available energy value is not zero and the estimated SOC value is zero, setting the estimated SOC value to a non - zero parameter, and in the case where it is monitored that the adjusted available energy value is zero, assigning the estimated SOC value to zero.

[0014] Preferably, the execution of the high - power SOC correction operation includes: determining whether there is a high - voltage single - cell battery in the energy storage system with a voltage value greater than or equal to a preset full - battery voltage; if there is such a high - voltage single - cell battery, obtaining the charge - discharge condition of the energy storage system; if the energy storage system is in a charging state, obtaining the third duration of the charging state; in the case where the third duration reaches a third time threshold and the available energy value reaches 100%, assigning the estimated SOC value to 100.

[0015] Correspondingly, the present invention further provides a SOC correction device for an energy storage system applied to a flywheel frequency modulation system. The device includes: a first judgment unit for judging whether the current meets a preset rapid SOC correction condition; an acquisition unit for acquiring the estimated SOC value of the energy storage system when the preset rapid SOC correction condition is met; a second judgment unit for judging whether the estimated SOC value is within a rapid correction interval, where the rapid correction interval is located in the plateau region of the OCV curve of the energy storage system; a first correction unit for performing a rapid correction operation when the estimated SOC value is within the rapid correction interval; a second correction unit for performing a low-battery SOC correction operation when the estimated SOC value is less than the rapid correction interval; and a third correction unit for performing a high-battery SOC correction operation when the estimated SOC value is greater than the rapid correction interval.

[0016] On the other hand, the present invention further provides a processor for running a program, where the program, when run, is used to execute the method provided by the embodiments of the present invention.

[0017] On the other hand, the present invention further provides a computer-readable storage medium having a computer program stored thereon, and the program, when executed by a processor, implements the method provided by the embodiments of the present invention.

[0018] Through the technical solution provided by the present invention, the present invention has at least the following technical effects:

[0019] By analyzing the physical characteristics of the lithium iron phosphate battery in detail, and aiming at its physical characteristics in the step region of the plateau region, as well as its physical characteristics in the empty-battery state, full-battery state, and large-current discharge state, a targeted SOC correction strategy is adopted to improve the traditional SOC correction method, realizing faster and more accurate SOC correction, greatly improving the accuracy and efficiency of SOC correction, meeting higher business requirements in specific scenarios, and meeting the actual needs of enterprises.

[0020] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent specific implementation part. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings are used to provide a further understanding of the embodiments of the present invention, and constitute a part of the specification, and are used to explain the embodiments of the present invention together with the following specific implementation manners, but do not constitute a limitation to the embodiments of the present invention. In the drawings:

[0022] Figure 1 is a schematic diagram of the OCV curve of the lithium iron phosphate battery provided by the embodiments of the present invention;

[0023] Figure 2It is a specific implementation flowchart of the SOC correction method for the energy storage system applied to the flywheel frequency modulation system provided by the embodiments of the present invention;

[0024] Figure 3 It is a schematic structural diagram of the SOC correction device for the energy storage system applied to the flywheel frequency modulation system provided by the embodiments of the present invention. Detailed implementation manners

[0025] The following details the specific implementation manners of the embodiments of the present invention in conjunction with the accompanying drawings. It should be understood that the specific implementation manners described herein are only used to illustrate and explain the embodiments of the present invention, and are not used to limit the embodiments of the present invention.

[0026] The terms "system" and "network" in the embodiments of the present invention can be used interchangeably. "Multiple" means two or more. In view of this, "multiple" in the embodiments of the present invention can also be understood as "at least two". "And / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " generally represents an "or" relationship between the associated objects before and after, unless otherwise specified. In addition, it should be understood that in the description of the embodiments of the present invention, terms such as "first" and "second" are only used for the purpose of distinguishing descriptions, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying order.

[0027] The background technology of the present invention is introduced below.

[0028] In the battery configuration of the existing energy storage system, there are batteries such as lithium iron phosphate batteries and ternary lithium batteries. In power scenarios and large-scale energy storage scenarios, lithium iron phosphate batteries are more widely used. Please refer to Figure 1 , which is the static discharge SOC-OCV curve of the lithium iron phosphate battery. It can be seen from the figure that the curve only has good linearity at both ends, there is a plateau region in the middle, and the voltage in the plateau region does not change significantly with the change of energy, which greatly increases the difficulty of SOC correction for the battery. In ordinary application scenarios, accurate monitoring only needs to be carried out when the energy storage system is almost fully charged or almost fully discharged to meet the requirements. Therefore, the inaccurate SOC monitoring caused by the above-mentioned plateau region has little impact on users. However, in special application scenarios such as flywheel frequency modulation systems, since it is necessary to accurately control the energy storage amount of the energy storage system in the middle region to cope with extreme discharge or extreme charge conditions, the traditional SOC correction method cannot meet the application requirements in special scenarios.

[0029] Please refer to Figure 2 , the embodiments of the present invention provide a SOC correction method for the energy storage system applied to the flywheel frequency modulation system. The method includes:

[0030] S10: Determine whether the preset fast SOC calibration condition is currently satisfied;

[0031] S20: If the preset fast SOC calibration condition is satisfied, obtain the estimated SOC value of the energy storage system;

[0032] S30: Determine whether the estimated SOC value is within the fast calibration interval, and the fast calibration interval is located in the plateau region of the OCV curve of the energy storage system;

[0033] S41: If the estimated SOC value is within the fast calibration interval, perform a fast calibration operation;

[0034] S42: If the estimated SOC value is less than the fast calibration interval, perform a low-battery SOC calibration operation;

[0035] S43: If the estimated SOC value is greater than the fast calibration interval, perform a high-battery SOC calibration operation.

[0036] In a possible implementation manner, during the application process of the energy storage system, the master control center configured for the energy storage system, such as the battery management system (BMS), monitors in real time whether the energy storage system satisfies the fast SOC calibration condition. For example, in this embodiment, although the voltage of the energy storage system fluctuates non-linearly during use instead of changing linearly according to the usage situation, after it is deactivated or placed for 10 minutes, its fluctuation range gradually converges, and the deviation caused by the fluctuation is within an acceptable range. At the same time, the duration of this time will not cause trouble to the user (an overly long waiting duration will cause the user's impatience and other emotions). Therefore, when the deactivation time of the energy storage system reaches 10 minutes, it can be regarded as satisfying the fast SOC calibration condition. Of course, those skilled in the art can adjust the above judgment time according to the actual configuration of the energy storage system and the actual needs of the user to adapt to the actual needs of specific scenarios, and no more details will be elaborated here.

[0037] For example, at a certain moment, if it is determined that the energy storage system meets the preset rapid SOC correction condition, the estimated SOC value of the energy storage system is immediately obtained. This estimated SOC value is the value obtained according to the traditional SOC estimation method and is used to be displayed to the user in real time through the display screen. In the actual application process, due to the defects of the traditional SOC correction method, there may be a large deviation between the estimated SOC value and the actual SOC value. At this time, a precise analysis is carried out in combination with the actual situation of the energy storage system. Since there is a section in the plateau region with good linear step characteristics, the SOC value of the energy storage system can be quickly corrected in this region. Specifically, it is judged whether the estimated SOC value is within the rapid correction interval. For example, in the embodiment of the present invention, this step interval is used as the rapid correction interval. Preferably, this step interval is 50%-70%. Of course, in order to further improve the accuracy of the rapid SOC correction, those skilled in the art can experiment with the precise step interval according to the actual physical characteristics of the current energy storage system, which will not be elaborated here too much.

[0038] In the first embodiment, the energy storage system monitors that the current estimated SOC value is within this rapid correction interval, so a rapid correction operation is immediately performed on the energy storage system.

[0039] In the embodiment of the present invention, the performing the rapid correction operation includes: obtaining a rapid OCV table; obtaining the current voltage value of the energy storage system; determining the actual SOC value from the rapid OCV table based on the current voltage value; judging whether the deviation between the actual SOC value and the estimated SOC value is greater than the deviation threshold; if so, replacing the estimated SOC value with the actual SOC value.

[0040] Since the lithium iron phosphate battery has good linear characteristics in the step interval of the OCV curve, its capacity and voltage can be sampled and tested in advance to form corresponding tabular data to accurately determine the corresponding relationship between the actual capacity and voltage in this step interval. In the subsequent SOC correction process, it can be directly corrected quickly by looking up the table.

[0041] In the embodiment of the present invention, the obtaining the rapid OCV table includes: determining the step range of the plateau region in the OCV curve of the energy storage system; performing multiple discharge processes on the energy storage system within the step range to obtain the first voltage data of the energy storage system at the unit OCV value, and generating a discharge OCV table based on the first voltage data; performing multiple charge processes on the energy storage system within the step range to obtain the second voltage data of the energy storage system at the unit OCV value, and generating a charge OCV table based on the second voltage data; generating a rapid OCV table based on the discharge OCV table and the charge OCV table.

[0042] For example, in the embodiments of the present invention, the step range is pre-determined to be 50% - 70%. Therefore, an accurate voltage relationship table within the range of 50% - 70% of SOC, that is, a fast OCV table, is established. Since the voltage change relationships under charging and discharging conditions of the battery are inconsistent, the corresponding voltage data can be collected separately and finally a fast OCV table is formed. Specifically, in the discharge sampling test link: First, fully charge the energy storage system. For example, charge the single cell to 3.65V at a constant current of 1C, and then charge at a constant voltage of 3.65V and stop charging when the current is less than 0.05C, which is determined to be fully charged. During the discharge process, in the existing standards or test specifications, the OCV curve data provided by the battery manufacturer are all measured values after the battery has been static for 180 minutes after discharge to ensure sufficient accuracy. However, in actual application scenarios, customers cannot wait for such a long time, so it cannot meet the actual needs.

[0043] In the embodiments of the present invention, combined with the actual physical characteristics of the battery after charge and discharge, and the detection deviation acceptable to the user, 10 minutes is determined as the acceptable waiting time. Based on this, after full charge, first, according to the capacity of the single cell, control the discharge device to perform a 30% capacity discharge at a discharge current of 1C, and then stand still for 30 minutes, that is, ensure that the discharge operations starting from 70% capacity are all discharge operations with accurate starting capacity. Further, in order to reduce the operation complexity and avoid reducing the work efficiency due to excessive rounds of discharge operations, according to the detection accuracy of the current detection device, it is determined to adopt a unit discharge operation with an interval of 2% of the capacity. Of course, those skilled in the art can determine a more appropriate sampling interval according to the actual accuracy of the current detection device, which will not be elaborated here. After each discharge operation is completed, stand still for 10 minutes, and then continue the next discharge operation until it is repeated 10 times, thus the cumulative discharge reaches 20%, that is, the discharge operation from 70% to 50% is completed, and the voltage data of the even capacities in this interval are obtained.

[0044] At this time, further, fully charge this single cell again, then perform a 31% capacity discharge, and then further perform the above 10 - cycle discharge operations to obtain the discharge operations from 69% - 49%, and obtain the voltage data of the odd capacities in this interval. Thus, the fast discharge OCV list values of the single cell in the 70% - 50% section are obtained. In the charging sampling test link, based on the same principle as above, charging sampling is carried out, and the fast charging OCV list values of the single cell in the 70% - 50% section are obtained. Thus, the overall fast OCV table of the single cell in this interval section is obtained.

[0045] In subsequent application processes, when the energy storage system is determined to meet the conditions for rapid SOC correction, if the estimated SOC value is within the rapid correction range (for example, 60% - 65%), the current voltage data of the energy storage system is directly obtained, and the corresponding actual SOC value is queried in the rapid OCV table, and it is determined whether the deviation between the estimated SOC value and the actual SOC value is greater than the specified deviation range. For example, the specified deviation range is 5%. If so, the estimated SOC value is forcibly corrected according to the queried actual SOC value, so as to quickly and accurately achieve the SOC correction of the energy storage system in the platform area, enabling the energy storage system to accurately control the input / output of the flywheel frequency modulation system according to its actual capacity and meet the actual working conditions requirements.

[0046] In the actual application process, under the control of the control system, the capacity of the energy storage system often changes in the platform area, that is, most of its working conditions operate in the range of 50% - 80% to meet the actual working conditions requirements. However, in the flywheel frequency modulation system, in order to meet the large current charge and discharge requirements of the flywheel frequency modulation system, the energy storage system is configured with solid batteries or semi-solid batteries. Therefore, in this energy storage system, charge and discharge operations are often carried out with a current greater than 1C (peak value 2C), and the specific charge and discharge parameters are determined by the grid power supply or discharge characteristics and are uncontrollable. The large current charge and discharge have a great impact on the sampling accuracy of the current detection device. On the one hand, it is easy for those skilled in the art to know that the greater the charge and discharge current, the lower the sampling accuracy, resulting in a deviation in SOC estimation; on the other hand, there are also phenomena such as cumulative deviation and natural discharge in the energy storage system during use, all of which have an impact on the deviation of SOC estimation. Therefore, in extreme working conditions, such as when the estimated SOC is at the end of the capacity, due to the deviation of the estimated SOC, problems of overcharge or over-discharge are likely to occur, greatly reducing the battery life and having an adverse impact on the normal operation of the flywheel frequency modulation system.

[0047] To solve the above technical problems, combined with the actual physical characteristics of the energy storage system discharging continuously at low power states and charging continuously at high power states, targeted end correction operations are carried out.

[0048] In the embodiment of the present invention, the execution of the low-power SOC correction operation includes: determining whether there is a low-voltage single-cell battery in the energy storage system whose voltage value is less than the preset empty-battery voltage; if there is such a low-voltage single-cell battery, obtaining the prior usage state of the energy storage system; in the case where the prior usage state is static discharge, obtaining the first continuous duration when the energy storage system is in a static state, and performing static SOC correction processing based on the first continuous duration; in the case where the prior usage state is a large current discharge state, obtaining the second continuous duration when the energy storage system is in the large current discharge state, the first continuous duration being greater than the second continuous duration, and performing dynamic SOC correction processing based on the second continuous duration.

[0049] In a possible implementation, the energy storage system detects that the current estimated SOC value is less than the rapid correction range, so it performs a low-battery SOC correction operation. Specifically, first, it determines whether there is a low-voltage single-cell battery in the energy storage system with a voltage value less than the preset empty-battery voltage. For example, the preset empty-battery voltage is 2500 mv. When the voltage of all batteries is higher than this value, it can be determined that the energy storage system still has a certain amount of power. However, since it is operating in the plateau region at this time, its accurate SOC value cannot be determined, so no SOC correction is performed. At a certain moment, the energy storage system detects that at least the voltage of a certain battery is less than 2500 mv, so it monitors its duration, and when the rapid SOC correction condition is triggered subsequently, the SOC value of the energy storage system is rapidly corrected.

[0050] Specifically, due to the different physical characteristics of the voltage value of the energy storage system in the static state and the high-current state, especially in the scenario of high current (discharging greater than 1C), the voltage value of the battery will drop rapidly, and the dropped value will gradually be greater than the voltage value corresponding to its actual capacity. And it will immediately rise after the discharge ends, and after about 3 hours, it will stabilize at the voltage value corresponding to its capacity. Therefore, in the embodiment of the present invention, after detecting a low-voltage single-cell battery with a voltage less than 2500 mv, the prior usage state of the energy storage system is immediately obtained, and a corresponding correction strategy is adopted.

[0051] In the embodiment of the present invention, the SOC correction process based on the first duration includes: determining whether the first duration reaches a first time threshold; if the first duration reaches the first time threshold, assigning the estimated SOC value to zero; the dynamic SOC correction process based on the second duration includes: determining whether the second duration reaches a second time threshold; if the second duration reaches the second time threshold, determining whether the estimated SOC value is greater than a preset SOC limit value, and if the estimated SOC value is greater than the preset SOC limit value, replacing the estimated SOC value with the preset SOC limit value.

[0052] Specifically, if the prior usage state is static discharge, its voltage value is relatively corresponding to its actual SOC value. At this time, the first duration of this voltage value is continuously monitored. If the first duration reaches the first time threshold (for example, 30 min), it can be determined that the power of the energy storage system has been exhausted. If the estimated SOC value is not zero at this time, the estimated SOC value of the energy storage system can be forcibly assigned to zero to prompt the user that the power of the current energy storage system has been exhausted.

[0053] If the prior usage state is high-current discharge, obtain the second duration of high-current discharge. If this second duration reaches the second time threshold (e.g., 10 s), first determine whether the estimated SOC is greater than the preset SOC limit value (e.g., 15%). If the estimated SOC is greater than 15%, forcefully assign the estimated SOC as 15% to correct the actual SOC of the energy storage system.

[0054] In the embodiments of the present invention, by adopting a targeted SOC correction strategy according to the actual physical characteristics of low-power discharge, the interference suffered during the SOC correction process is effectively avoided, and the accuracy of SOC correction when the energy storage system discharges at the end is improved. However, in the high-current discharge scenario, if the estimated SOC is less than or equal to 15% at this time, due to the influence of high-current discharge, it is impossible to determine whether the power of the energy storage system has been exhausted, thus affecting the SOC correction at the end.

[0055] In the embodiments of the present invention, the method further includes: initializing the available energy value of the energy storage system; obtaining the operating voltage and operating current of the energy storage system in real time, and adjusting the available energy value based on the operating voltage and the operating current; if the estimated SOC value is less than the preset SOC limit value, determine whether the adjusted available energy value is zero: if the adjusted available energy value is zero, assign the estimated SOC value as zero; if the adjusted available energy value is not zero and the estimated SOC value is zero, set the estimated SOC value to a non-zero parameter, and when it is monitored that the adjusted available energy value is zero, assign the estimated SOC value as zero.

[0056] In a possible implementation manner, using the principle of energy conservation, the concept of the available energy value of the energy storage system is introduced to assist in more accurate SOC correction operations. Specifically, when the energy storage system is first used, a full charge operation is performed on it. At this time, the available energy value of the energy storage system can be calculated according to the rated power of the energy storage system or the voltage and current changes during the full charge process. During the subsequent use of the energy storage system, the above available energy value will be dynamically adjusted automatically according to the voltage and current changes during the discharge process and the voltage and current changes during the charging process.

[0057] During the application process, when in a high-current discharge scenario, if a low-voltage single-cell battery with a detected voltage less than 2500 mV is detected due to high-current discharge, and if the estimated SOC is less than 15% at this time, its actual SOC is not immediately corrected to zero. Instead, the remaining electric energy is further estimated by combining the available energy value. For example, in one embodiment, after 15 s of high-current discharge in the energy storage system, at least one low-voltage single-cell battery is detected. Therefore, the available energy value is immediately queried and found to be 10%. Then, the discharge operation is continued until the available energy value is reduced to zero, and then the estimated SOC is corrected to zero, thus completing the accurate correction of the SOC of the energy storage system at the low-voltage end.

[0058] In another embodiment, due to the influence of the actual usage conditions, especially in the case of high-current discharge, the deviation of current detection or voltage detection will cause abnormal changes in the available energy value, resulting in a situation where the available energy value drops to zero in advance while the electric energy of the actual energy storage system has not been exhausted. That is, in this embodiment, if the available energy value is detected to be zero but the estimated SOC is not zero, the available energy value is set to a non-zero parameter at this time, and the energy storage system is controlled to continue discharging. When the discharge current of the energy storage system is zero or it cannot continue to discharge, the available energy value is corrected to zero, and at the same time, the estimated SOC is corrected to zero, thus achieving double and accurate correction of the SOC value and the available energy value of the energy storage system.

[0059] In the embodiment of the present invention, by introducing an independent parameter of the available energy value, the electric energy during the use of the energy storage system is independently monitored to assist in objectively reference-correcting the SOC correction of the energy storage system, thereby further improving the accuracy of SOC correction for the end-of-life capacity of the energy storage system and meeting the actual requirements.

[0060] In the embodiment of the present invention, the execution of the high-voltage SOC correction operation includes: determining whether there is a high-voltage single-cell battery in the energy storage system with a voltage value greater than or equal to the preset full-charge voltage; if there is such a high-voltage single-cell battery, obtaining the charge-discharge working condition of the energy storage system; if the energy storage system is in a charging state, obtaining the third duration of the charging state; and when the third duration reaches the third time threshold and the available energy value reaches 100%, assigning the estimated SOC value to 100.

[0061] In a possible implementation, after determining that the energy storage system meets the preset fast SOC correction condition, if the estimated SOC value is greater than the fast correction interval at this time, and if it is discharging, no SOC fast correction is performed on it. If it is charging at this time, once the voltage value of a certain single cell reaches the preset full charge voltage (for example, 3650 mv), the third duration in the charging state is further obtained. If the third duration reaches the third time threshold and the available energy value reaches 100%, it can be determined that the energy storage system is fully charged, and the estimated SOC value is assigned 100.

[0062] Of course, based on the same principle, in the second embodiment, if during the application of the energy storage system, it is monitored that the available energy value is 100%, but the estimated SOC value is less than 100% or there is still a charging current, the available energy value is not continuously accumulated. Instead, the charging process of the energy storage system is continuously monitored, and after it is monitored that the estimated SOC value of the energy storage system reaches 100% or there is no charging current, both the estimated SOC value and the available energy value are assigned 100% to implement the correction operation of the SOC and the available energy value.

[0063] In the embodiments of the present invention, by analyzing the physical characteristics of the lithium iron phosphate battery in detail and adopting different correction strategies at the middle, front, and back ends of the OCV curve using its physical characteristics, the actual SOC value is quickly and accurately corrected, greatly improving the accuracy and efficiency of SOC correction, meeting the higher requirements for SOC correction in specific scenarios, meeting the actual needs of users, better supporting the business requirements for the energy control accuracy of the energy storage system in specific scenarios, and improving the competitiveness of enterprise products.

[0064] Please refer to Figure 3 , based on the same inventive concept, the embodiments of the present invention provide an SOC correction device for an energy storage system applied to a flywheel frequency modulation system. The device includes: a first judgment unit for judging whether the preset fast SOC correction condition is currently met; an acquisition unit for acquiring the estimated SOC value of the energy storage system when the preset fast SOC correction condition is met; a second judgment unit for judging whether the estimated SOC value is within the fast correction interval, and the fast correction interval is located in the plateau region of the OCV curve of the energy storage system; a first correction unit for performing a fast correction operation when the estimated SOC value is within the fast correction interval; a second correction unit for performing a low power SOC correction operation when the estimated SOC value is less than the fast correction interval; and a third correction unit for performing a high power SOC correction operation when the estimated SOC value is greater than the fast correction interval.

[0065] Furthermore, an embodiment of the present invention further provides a processor for running a program, where when the program is run, it is used to execute the method described in the embodiment of the present invention.

[0066] Furthermore, an embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the method described in the present invention is implemented.

[0067] The optional embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above embodiments. Within the scope of the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all fall within the protection scope of the embodiments of the present invention.

[0068] In addition, it should be noted that, in the above specific embodiments, the various specific technical features described can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention do not separately describe various possible combination methods.

[0069] Those skilled in the art can understand that all or part of the steps of implementing the above embodiments of the method can be completed by instructing relevant hardware through a program. The program is stored in a storage medium, including several instructions for causing a single-chip microcomputer, a chip, or a processor to execute all or part of the steps of the method described in various embodiments of the present application. The foregoing storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disc.

[0070] In addition, any combination can be made between various different embodiments of the embodiments of the present invention, as long as it does not violate the idea of the embodiments of the present invention, and it should also be regarded as the content disclosed in the embodiments of the present invention.

Claims

1. A method for correcting the SOC of an energy storage system applied to a flywheel frequency modulation system, characterized in that The method includes: Judging whether the preset fast SOC correction condition is satisfied currently; If the preset fast SOC correction condition is satisfied, obtaining the estimated SOC value of the energy storage system; Judging whether the estimated SOC value is within the fast correction interval, where the fast correction interval is located in the plateau region of the OCV curve of the energy storage system; If the estimated SOC value is within the fast correction interval, performing a fast correction operation; If the estimated SOC value is less than the fast correction interval, performing a low power SOC correction operation; If the estimated SOC value is greater than the fast correction interval, performing a high power SOC correction operation; The performing of the low power SOC correction operation includes: Judging whether there is a low voltage single cell in the energy storage system whose voltage value is less than the preset empty battery voltage; If there is such a low voltage single cell, obtaining the prior usage state of the energy storage system; In the case where the prior usage state is static discharge, obtaining the first duration of the energy storage system in a static state, and performing static SOC correction processing based on the first duration; In the case where the prior usage state is a large current discharge state, obtaining the second duration of the energy storage system in the large current discharge state, where the first duration is greater than the second duration, and performing dynamic SOC correction processing based on the second duration; The performing of the static SOC correction processing based on the first duration includes: Judging whether the first duration reaches a first time threshold; If the first duration reaches the first time threshold, assigning the estimated SOC value to zero; The performing of the dynamic SOC correction processing based on the second duration includes: Judging whether the second duration reaches a second time threshold; If the second duration reaches the second time threshold, judging whether the estimated SOC value is greater than a preset SOC limit value, and if the estimated SOC value is greater than the preset SOC limit value, replacing the estimated SOC value with the preset SOC limit value.

2. The method according to claim 1, wherein The performing of the fast correction operation includes: Obtaining a fast OCV table; Obtaining the current voltage value of the energy storage system; Determining the actual SOC value from the fast OCV table based on the current voltage value; Judging whether the deviation between the actual SOC value and the estimated SOC value is greater than a deviation threshold; If so, replacing the estimated SOC value with the actual SOC value.

3. The method according to claim 2, wherein The obtaining of the fast OCV table includes: Determining the step range of the plateau region in the OCV curve of the energy storage system; Performing multiple discharge processes on the energy storage system within the step range to obtain first voltage data of the energy storage system at a unit OCV value, and generating a discharge OCV table based on the first voltage data; Performing multiple charge processes on the energy storage system within the step range to obtain second voltage data of the energy storage system at a unit OCV value, and generating a charge OCV table based on the second voltage data; Generating a fast OCV table based on the discharge OCV table and the charge OCV table.

4. The method according to claim 1, wherein The method further includes: Initializing the available energy value of the energy storage system; Obtain the operating voltage and operating current of the energy storage system in real time, and adjust the available energy value based on the operating voltage and the operating current; If the estimated SOC value is less than the preset SOC limit value, determine whether the adjusted available energy value is zero: If the adjusted available energy value is zero, assign the estimated SOC value to zero; If the adjusted available energy value is not zero and the estimated SOC value is zero, set the estimated SOC value to a non-zero parameter, and when it is monitored that the adjusted available energy value is zero, assign the estimated SOC value to zero.

5. The method according to claim 4, wherein The execution of the high battery SOC correction operation includes: Determine whether there is a high-voltage single-cell battery in the energy storage system with a voltage value greater than or equal to the preset full-charge voltage; If there is the high-voltage single-cell battery, obtain the charge-discharge working condition of the energy storage system; If the energy storage system is in the charging state, obtain the third duration of the charging state; When the third duration reaches the third time threshold and the available energy value reaches 100%, assign the estimated SOC value to 100.

6. An energy storage system SOC correction device applied to a flywheel frequency modulation system, characterized in that The device includes: A first judgment unit for judging whether the preset fast SOC correction condition is currently satisfied; An acquisition unit for acquiring the estimated SOC value of the energy storage system when the preset fast SOC correction condition is satisfied; A second judgment unit for judging whether the estimated SOC value is within the fast correction interval, and the fast correction interval is located in the flat region of the OCV curve of the energy storage system; A first correction unit for performing a fast correction operation when the estimated SOC value is within the fast correction interval; A second correction unit for performing a low-battery SOC correction operation when the estimated SOC value is less than the fast correction interval; A third correction unit for performing a high-battery SOC correction operation when the estimated SOC value is greater than the fast correction interval; The second correction unit is specifically used for: Determine whether there is a low-voltage single-cell battery in the energy storage system with a voltage value less than the preset empty-battery voltage; If there is the low-voltage single-cell battery, obtain the prior usage state of the energy storage system; When the prior usage state is static discharge, obtain the first duration of the energy storage system in a static state, and perform static SOC correction processing based on the first duration; When the prior usage state is a large-current discharge state, obtain the second duration of the energy storage system in the large-current discharge state, the first duration is greater than the second duration, and perform dynamic SOC correction processing based on the second duration; The performing static SOC correction processing based on the first duration includes: Determine whether the first duration reaches the first time threshold; If the first duration reaches the first time threshold, assign the estimated SOC value to zero; The performing dynamic SOC correction processing based on the second duration includes: Determine whether the second duration reaches the second time threshold; If the second duration reaches the second time threshold, determine whether the estimated SOC value is greater than a preset SOC limit value. If the estimated SOC value is greater than the preset SOC limit value, replace the estimated SOC value with the preset SOC limit value.

7. A processor, characterized in that, For running a program, wherein when the program is run, it is used to execute the method according to any one of claims 1-5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by a processor, it implements the method according to any one of claims 1-5.

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