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

Abstract

The invention relates to the technical field of SOC correction, and particularly discloses an energy storage system SOC correction method and device applied to a flywheel frequency modulation system, a processor and a storage medium, and the method comprises the steps: judging whether a preset rapid SOC correction condition is met at present or not; if the preset fast SOC correction condition is met, obtaining an estimated SOC value of the energy storage system; judging whether the estimated SOC value is in a rapid correction interval or not; if the estimated SOC value is in the rapid correction interval, executing rapid correction operation; if the estimated SOC value is smaller than the rapid correction interval, low-electric-quantity SOC correction operation is executed; and if the estimated SOC value is greater than the rapid correction interval, executing a high-electric-quantity SOC correction operation. Accurate SOC correction is carried out on the middle part and the tail end of the lithium iron phosphate battery in the use process by utilizing the actual physical characteristics of the lithium iron phosphate battery in the use process, so that the monitoring accuracy of the energy storage system on the battery capacity is improved, the SOC monitoring accuracy is improved, the service requirements of specific scenes are met, and the actual requirements of enterprises are met.

Description

Technical Field

[0001] The present invention relates to the field of SOC correction technology, and in particular to a SOC correction method for an energy storage system applied to a flywheel frequency modulation system, a SOC correction device for 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 had an impact on the power grid. In order to solve this technical problem, technicians use energy storage systems to store and buffer the electricity generated by new energy, such as using flywheels for energy conversion.

[0003] In the field of traditional on-board new energy control, the operating conditions are relatively stable and the charging and discharging are managed by the on-board controller, so the power management is relatively simple and accurate. However, when it is applied to the flywheel system, the operation of the flywheel is highly random and the charging and discharging are uncontrollable at any time. The battery system is required to work effectively in the range of 50% to 80% 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, since the open-circuit voltage of lithium iron phosphate cells is not linearly representative and has a plateau period, there is a certain deviation in the correction of SOC, and the flywheel frequency modulation system has occasional large current input / output. 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 input / output of the flywheel frequency modulation system, and thus cannot meet actual usage needs.

[0005] Secondly, compared to conventional electricity usage scenarios where the battery can be fully charged or fully discharged, the energy storage system lacks the opportunity for end-point calibration when used in the above application scenarios. Therefore, the calibration requirements and accuracy in the 50-80% range cannot be guaranteed, and the capacity in this range cannot be effectively evaluated and monitored.

[0006] On the other hand, when a semi-solid or solid-state battery system is used, large current charging and discharging are allowed. At this time, the current change increases, and the large current operating condition will have an abnormal impact on the voltage, further leading to large deviations in SOC estimation. Therefore, the existing SOC correction method cannot meet actual needs. Summary of the invention

[0007] In order to overcome the above-mentioned technical problems existing in the prior art, the embodiments of the present invention provide 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 properties of the lithium iron phosphate battery during use, accurate SOC correction is performed in the middle and end of use, thereby improving the accuracy of the energy storage system's monitoring of the battery capacity, improving the accuracy of SOC monitoring, achieving the business needs of specific scenarios, and satisfying the actual needs of the enterprise.

[0008] In order to achieve the above-mentioned purpose, an embodiment of the present invention provides an energy storage system SOC correction method applied to a flywheel frequency modulation system, the method comprising: judging whether a preset fast SOC correction condition is currently met; if the preset fast SOC correction condition is met, obtaining an estimated SOC value of the energy storage system; judging whether the estimated SOC value is located in a fast correction interval, the fast correction interval being located in a platform area of ​​an 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 of the quick correction operation includes: obtaining a quick OCV table; obtaining a current voltage value of the energy storage system; determining an actual SOC value from the quick OCV table based on the current voltage value; determining whether a deviation between the actual SOC value and the estimated SOC value is greater than a deviation threshold; and if so, replacing the estimated SOC value based on the actual SOC value.

[0010] Preferably, obtaining a fast OCV table comprises: determining a step range of a platform area in an 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; and generating a fast OCV table based on the discharge OCV table and the charge OCV table.

[0011] Preferably, the execution of the low-battery SOC correction operation includes: determining whether there is a low-voltage single cell in the energy storage system whose voltage value is less than a preset empty-battery voltage; if the low-voltage single cell exists, obtaining a previous use state of the energy storage system; when the previous use state is static discharge, obtaining a first duration that the energy storage system is in a static state, and performing a static SOC correction process based on the first duration; when the previous use state is a high-current discharge state, obtaining a second duration that the energy storage system is in the high-current discharge state, the first duration being greater than the second duration, and performing a dynamic SOC correction process based on the second duration.

[0012] Preferably, the static SOC correction processing is performed based on the first duration, including: 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 processing is performed based on the second duration, including: 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 also includes: initializing the available energy value of the energy storage system; acquiring 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, 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 when monitoring that the adjusted available energy value is zero, assigning the estimated SOC value to zero.

[0014] Preferably, the high-power SOC correction operation includes: determining whether there is a high-voltage single cell in the energy storage system whose voltage value is greater than or equal to a preset full-charge voltage; if the high-voltage single cell exists, obtaining the charging and discharging condition of the energy storage system; if the energy storage system is in a charging state, obtaining a third duration of the charging state; when 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 also provides an energy storage system SOC correction device applied to a flywheel frequency regulation system, the device comprising: a first judgment unit, used to judge whether a preset fast SOC correction condition is currently met; an acquisition unit, used to acquire an estimated SOC value of the energy storage system when the preset fast SOC correction condition is met; a second judgment unit, used to judge whether the estimated SOC value is located in a fast correction interval, and the fast correction interval is located in the platform area of ​​the OCV curve of the energy storage system; a first correction unit, used to perform a fast correction operation when the estimated SOC value is located in the fast correction interval; a second correction unit, used to perform a low-power SOC correction operation when the estimated SOC value is less than the fast correction interval; and a third correction unit, used to perform a high-power SOC correction operation when the estimated SOC value is greater than the fast correction interval.

[0016] On the other hand, the present invention further provides a processor for running a program, wherein the program, when run, is used to execute the method provided by an embodiment 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, which implements the method provided by the embodiment of the present invention when the program is executed by a processor.

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

[0019] Through a detailed analysis of the physical properties of lithium iron phosphate batteries, targeted SOC correction strategies are adopted for their physical properties in the step zone in the platform area, as well as their physical properties in the empty state, fully charged state and high current discharge state, to improve the traditional SOC correction method, achieve faster and more accurate SOC correction, greatly improve the SOC correction accuracy and efficiency, meet higher business requirements in specific scenarios, and meet 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 detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0024] Figure 3 It is a structural schematic diagram of a SOC correction device for an energy storage system applied to a flywheel frequency modulation system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment 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 than two. In view of this, "multiple" can also be understood as "at least two" in the embodiments of the present invention. "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 at the same time, and B exists alone. In addition, the character " / ", unless otherwise specified, generally indicates that the previous and subsequent associated objects are in an "or" relationship. In addition, it should be understood that in the description of the embodiments of the present invention, the words "first", "second", etc. are only used to distinguish the purpose of description, 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] The battery configuration of the existing energy storage system includes lithium iron phosphate batteries, ternary lithium batteries and other batteries. In power scenarios and large-scale energy storage scenarios, lithium iron phosphate batteries are widely used. Figure 1 , is the static discharge SOC-OCV curve of lithium iron phosphate battery. As can be seen from the figure, the curve has good linearity only at the two ends, and there is a platform area in the middle. The voltage in the platform area does not change significantly with the change of energy, which greatly increases the difficulty of battery SOC correction. In ordinary application scenarios, it is only necessary to accurately monitor the energy storage system when it is almost full or almost discharged to meet the needs. Therefore, the inaccurate SOC monitoring caused by the above platform area has little impact on users. In special application scenarios such as flywheel frequency modulation systems, since it is necessary to accurately control the energy storage capacity of the energy storage system in the middle area to cope with extreme discharge or extreme charging conditions, the traditional SOC correction method cannot meet the application needs in special scenarios.

[0029] See also Figure 2 The embodiment of the present invention provides a method for correcting the SOC of an energy storage system applied to a flywheel frequency modulation system, the method comprising:

[0030] S10: Determine whether a preset fast SOC correction condition is currently met;

[0031] S20: If the preset fast SOC correction condition is met, obtaining an estimated SOC value of the energy storage system;

[0032] S30: Determine whether the estimated SOC value is in a rapid correction interval, the rapid correction interval being in a platform area of ​​an OCV curve of the energy storage system;

[0033] S41: If the estimated SOC value is within the rapid correction interval, performing a rapid correction operation;

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

[0035] S43: If the estimated SOC value is greater than the fast correction interval, a high-power SOC correction operation is performed.

[0036] In a possible implementation, during the application of the energy storage system, a main control center configured by the energy storage system, such as a battery management system (BMS), monitors in real time whether the energy storage system meets the fast SOC correction condition. For example, in this embodiment, although the voltage of the energy storage system will produce nonlinear fluctuations during use, rather than linear changes according to the usage, 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 length of this time will not cause trouble to the user (too long waiting time will cause the user's impatience and other emotions). Therefore, when the energy storage system is deactivated for 10 minutes, it can be regarded as meeting the fast SOC correction condition. Of course, technicians 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 the specific scenario, and no further elaboration will be made here.

[0037] For example, at a certain moment, if it is determined that the energy storage system meets the preset rapid SOC correction conditions, the estimated SOC value of the energy storage system is immediately obtained. The estimated SOC value is a value obtained according to the traditional SOC estimation method. The value is used to display to the user in real time through the display screen. In actual application, due to the defects of the traditional SOC correction method, the estimated SOC value and the actual SOC value may have a large deviation. At this time, the energy storage system is accurately analyzed in combination with its actual situation. Since there is a section in the platform area with good linear step characteristics, the SOC value of the energy storage system can be quickly corrected in this area. Specifically, it is determined whether the estimated SOC value is in the rapid correction interval. For example, in an embodiment of the present invention, the step interval is used as a rapid correction interval. Preferably, the step interval is 50%-70%. Of course, in order to further improve the accuracy of the SOC rapid correction, technicians can test the precise step interval based on the actual physical characteristics of the current energy storage system, which will not be elaborated here.

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

[0039] In an embodiment of the present invention, the fast correction operation includes: obtaining a fast OCV table; obtaining a 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 a deviation between the actual SOC value and the estimated SOC value is greater than a deviation threshold; and if so, replacing the estimated SOC value based on the actual SOC value.

[0040] Since lithium iron phosphate batteries have good linear characteristics in the step interval of the OCV curve, capacity and voltage sampling tests can be carried out in advance and corresponding table data can be formed to accurately determine the corresponding relationship between the actual capacity and voltage in the step interval. In the subsequent SOC correction process, it can be quickly corrected by directly looking up the table.

[0041] In an embodiment of the present invention, the obtaining of a fast OCV table includes: determining a step range of a platform area in an 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; and generating a fast OCV table based on the discharge OCV table and the charge OCV table.

[0042] For example, in an embodiment of the present invention, the step range is predetermined to be 50%-70%, so an accurate voltage relationship table of SOC in the range of 50%-70% is established, that is, a fast OCV table. Since the voltage change relationship of the battery under charging and discharging conditions is 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, the energy storage system is fully charged, for example, the single cell is charged to 3.65V at a constant current of 1C, and then charged at a constant voltage of 3.65V, and the charging is stopped when the current is less than 0.05C, and it is determined to be fully charged. In the process of discharging, 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 left to stand for 180 minutes after discharge to ensure sufficient accuracy. However, in actual application scenarios, customers cannot wait for such a long time, so the actual needs cannot be met.

[0043] In the embodiment of the present invention, combined with the actual physical characteristics of the battery after charging and discharging, and the user's acceptable detection deviation, 10 minutes is determined to be an acceptable waiting time. Based on this, after full charging, first, according to the capacity of the single cell, the discharge device is controlled to perform 30% capacity discharge according to the 1C discharge current, and then it is rested for 30 minutes, that is, it is ensured that the discharge operation starting from 70% capacity is a discharge operation with an accurate starting capacity. Further, in order to reduce the complexity of the operation and avoid too many rounds of discharge operations to reduce work efficiency, according to the detection accuracy of the current detection device, it is determined to use a unit discharge operation with a capacity interval of 2%. Of course, the technician can determine a more appropriate sampling interval according to the actual accuracy of the current detection device, and no further details are given here. After each discharge operation is performed, it is rested for 10 minutes, and then the next discharge operation is continued until it is repeated 10 times, so that the cumulative discharge reaches 20%, that is, the discharge operation from 70% to 50% is completed, and the voltage data of the even capacity in this interval is obtained.

[0044] At this point, the single cell is further fully charged, and then discharged to 31% capacity, and then the above 10 cycles of discharge operation are further performed to obtain the discharge operation from 69% to 49%, and the voltage data of the odd capacity in this interval are obtained, thereby obtaining the single cell fast discharge OCV list value in the 70%-50% segment. In the charging sampling test phase, based on the same principle as above, charging sampling is performed, and the single cell fast charging OCV list value in the 70%-50% segment is obtained, thereby obtaining the overall fast OCV table of the single cell in this interval.

[0045] In the subsequent application process, when the energy storage system is judged to meet the fast SOC correction conditions, if the estimated SOC value is in the fast correction interval (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 fast 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, such as 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 realize the SOC correction of the energy storage system in the platform area, so that the energy storage system can accurately control the input / output of the flywheel frequency regulation system according to its actual capacity to meet the actual working conditions.

[0046] In actual application, 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 are operated in the range of 50%-80% to meet the actual working conditions. However, in the flywheel frequency modulation system, in order to meet the large current charging and discharging requirements of the flywheel frequency modulation system, the energy storage system is equipped with a solid battery or a semi-solid battery. Therefore, in this energy storage system, the charging and discharging operation is often performed with a current greater than 1C (peak 2C), and the specific parameters of charging and discharging are determined by the grid power replenishment or discharge characteristics and are uncontrollable. The large current charging and discharging has a great impact on the sampling accuracy of the current detection device. On the one hand, it is easy for technicians in this field to know that the larger the charging and discharging current, the lower the sampling accuracy, which causes the deviation of SOC estimation; on the other hand, the energy storage system also has cumulative deviations, natural discharge and other phenomena during use, which cause deviations in the estimation of SOC. Therefore, under extreme working conditions, such as when the estimated SOC is at the end of the capacity, due to the deviation of the estimated SOC, it is very easy to cause overcharging or over-discharging problems, which greatly reduces the battery life and has an adverse effect on the normal operation of the flywheel frequency modulation system.

[0047] In order to solve the above technical problems, targeted terminal correction operations are performed based on the actual physical characteristics of the energy storage system's continuous discharge in a low-power state and continuous charging in a high-power state.

[0048] In an embodiment of the present invention, the low-battery SOC correction operation includes: determining whether there is a low-voltage single cell in the energy storage system whose voltage value is less than a preset empty-battery voltage; if the low-voltage single cell exists, obtaining a previous use state of the energy storage system; when the previous use state is static discharge, obtaining a first duration of time that the energy storage system is in a static state, and performing a static SOC correction process based on the first duration; when the previous use state is a high-current discharge state, obtaining a second duration of time that the energy storage system is in the high-current discharge state, the first duration being greater than the second duration, and performing a dynamic SOC correction process based on the second duration.

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

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

[0051] In an embodiment of the present invention, the SOC correction processing performed 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 processing performed 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 previous usage state is static discharge, its voltage value corresponds to its actual SOC value. At this time, the first duration of the voltage value is continuously monitored. If the first duration reaches a first time threshold (for example, 30 minutes), it can be determined that 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 current energy storage system has been exhausted.

[0053] If the previous usage state is high-current discharge, a second duration of high-current discharge is obtained. If the second duration reaches a second time threshold (for example, 10s), first determine whether the estimated SOC is greater than a preset SOC limit (for example, 15%). If the estimated SOC is greater than 15%, the estimated SOC is forcibly assigned to 15% to correct the actual SOC of the energy storage system.

[0054] In the embodiment of the present invention, a targeted SOC correction strategy is adopted based on the actual physical characteristics of low-power discharge, which effectively avoids interference in the SOC correction process and improves the accuracy of SOC correction of the energy storage system during terminal discharge. However, in the high-current discharge scenario, if the estimated SOC is less than or equal to 15% at this time, it is impossible to determine whether the energy storage system has been exhausted due to the influence of high-current discharge, which affects the terminal SOC correction.

[0055] In an embodiment of the present invention, the method also includes: initializing the available energy value of the energy storage system; acquiring 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, 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 when monitoring that the adjusted available energy value is zero, assigning the estimated SOC value to zero.

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

[0057] During the application process, when a low-voltage single cell with a voltage less than 2500mv is detected due to high-current discharge in a high-current discharge scenario, if the estimated SOC is less than 15% at this time, the actual SOC is not immediately corrected to zero, but the remaining electric energy is further estimated in combination with the available energy value. For example, in one embodiment, after 15s of high-current discharge, the energy storage system detects the presence of at least one low-voltage single cell, so it immediately queries the available energy value and finds that the available energy value is 10%, so it continues to perform the discharge operation until the available energy value is reduced to zero, and then the estimated SOC is corrected to zero, thereby completing the precise correction of the SOC of the energy storage system at the low-voltage end.

[0058] In another embodiment, due to the influence of actual use 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 the available energy value dropping to zero in advance, while the actual energy storage system's power 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 equal to zero, then the available energy value is set to a non-zero parameter, and the energy storage system is controlled to continue discharging, and only when the discharge current of the energy storage system is zero or cannot continue to discharge, the available energy value is corrected to zero, and the estimated SOC is corrected to zero at the same time, thereby achieving dual 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 independent available energy value parameters, the electric energy of the energy storage system during use is independently monitored to assist in objective reference correction of the SOC correction of the energy storage system, thereby further improving the accuracy of the SOC correction of the terminal capacity of the energy storage system and meeting actual needs.

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

[0061] In one possible implementation, after determining that the energy storage system meets the preset fast SOC correction conditions, if the estimated SOC value at this time is greater than the fast correction interval, 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 single battery cell is monitored to reach the preset full-charge voltage (for example, 3650mv), the third duration of 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 to 100.

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

[0063] In the embodiment of the present invention, by conducting a detailed analysis of the physical properties of the lithium iron phosphate battery, different correction strategies are adopted in the middle, front and back ends of the OCV curve by utilizing its physical properties, so as to quickly and accurately correct its actual SOC value, thereby greatly improving the SOC correction accuracy and correction efficiency, meeting higher requirements for SOC correction in specific scenarios, meeting the actual needs of users, better supporting the business needs for the energy control accuracy of the energy storage system in specific scenarios, and improving the competitiveness of enterprise products.

[0064] See also Figure 3 Based on the same inventive concept, an embodiment of the present invention provides an energy storage system SOC correction device applied to a flywheel frequency modulation system, the device comprising: a first judgment unit, used to judge whether a preset fast SOC correction condition is currently met; an acquisition unit, used to acquire an estimated SOC value of the energy storage system when the preset fast SOC correction condition is met; a second judgment unit, used to judge whether the estimated SOC value is located in a fast correction interval, and the fast correction interval is located in a platform area of ​​an OCV curve of the energy storage system; a first correction unit, used to perform a fast correction operation when the estimated SOC value is located in the fast correction interval; a second correction unit, used to perform a low-power SOC correction operation when the estimated SOC value is less than the fast correction interval; a third correction unit, used to perform 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, wherein the program, when being run, is used to execute the method described in the embodiment of the present invention.

[0066] Furthermore, an embodiment of the present invention also 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 implementation modes of the embodiments of the present invention are 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 implementation modes. Within the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical scheme of the embodiments of the present invention, and these simple modifications all belong to the protection scope of the embodiments of the present invention.

[0068] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not further describe various possible combinations.

[0069] Those skilled in the art can understand that all or part of the steps in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a program, and the program is stored in a storage medium, including a number of instructions to enable a single-chip microcomputer, a chip or a processor to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0070] In addition, various implementation modes of the embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the embodiments of the present invention, they should also be regarded as the contents disclosed by the embodiments of the present invention.

Claims

1. A SOC correction method for an energy storage system applied to a flywheel frequency modulation system, characterized in that: The method comprises: Determine whether the preset fast SOC correction condition is currently met; If the preset fast SOC correction condition is met, obtaining an estimated SOC value of the energy storage system; Determining whether the estimated SOC value is in a rapid correction interval, the rapid correction interval being in a platform area of ​​an OCV curve of the energy storage system; If the estimated SOC value is within the rapid correction interval, performing a rapid correction operation; If the estimated SOC value is less than the fast correction interval, performing a low-battery SOC correction operation; If the estimated SOC value is greater than the fast correction interval, a high-power SOC correction operation is performed.

2. The method according to claim 1, characterized in that The performing of the rapid correction operation comprises: Get a quick OCV table; Obtaining a 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 a deviation between the actual SOC value and the estimated SOC value is greater than a deviation threshold; If so, the estimated SOC value is replaced based on the actual SOC value.

3. The method according to claim 1, characterized in that The obtaining of the quick OCV table includes: Determine the step range of the platform region in the OCV curve of the energy storage system; Perform 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 generate a discharge OCV table based on the first voltage data; Perform multiple charging 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 generate a charging OCV table based on the second voltage data; A quick OCV table is generated based on the discharge OCV table and the charge OCV table.

4. The method according to claim 1, characterized in that The performing of the low power SOC correction operation includes: Determine whether there is a low-voltage single cell in the energy storage system whose voltage value is less than a preset empty-power voltage; If the low-voltage single cell exists, obtaining the previous use status of the energy storage system; In a case where the previous use state is static discharge, obtaining a first duration in which the energy storage system is in a static state, and performing a static SOC correction process based on the first duration; In the case where the previous use state is a high-current discharge state, a second duration of the energy storage system being in the high-current discharge state is obtained, the first duration is greater than the second duration, and a dynamic SOC correction process is performed based on the second duration.

5. The method according to claim 4, characterized in that The performing of a static 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 performing of a 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, determine 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, replace the estimated SOC value with the preset SOC limit value.

6. The method according to claim 5, characterized in that The method further comprises: Initializing the available energy value of the energy storage system; Acquire the operating voltage and the 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, 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, the estimated SOC value is set to a non-zero parameter, and when the adjusted available energy value is monitored to be zero, the estimated SOC value is assigned to zero.

7. The method according to claim 6, characterized in that The performing of the high-power SOC correction operation includes: Determine whether there is a high-voltage single cell in the energy storage system whose voltage value is greater than or equal to a preset full-charge voltage; If the high-voltage single cell exists, obtaining the charging and discharging conditions of the energy storage system; If the energy storage system is in a charging state, obtaining a third duration of the charging state; When the third duration reaches a third time threshold and the available energy value reaches 100%, the estimated SOC value is assigned a value of 100.

8. A SOC correction device for an energy storage system applied to a flywheel frequency modulation system, characterized in that: The device comprises: A first determination unit, used to determine whether a preset fast SOC correction condition is currently met; An acquisition unit, configured to acquire an estimated SOC value of the energy storage system when the preset fast SOC correction condition is met; A second judgment unit, used to judge whether the estimated SOC value is in a rapid correction interval, wherein the rapid correction interval is located in a platform area of ​​an OCV curve of the energy storage system; a first correction unit, configured to perform a rapid correction operation when the estimated SOC value is within the rapid correction interval; a second correction unit, configured to perform a low-battery SOC correction operation when the estimated SOC value is less than the fast correction interval; The third correction unit is used to perform a high-power SOC correction operation when the estimated SOC value is greater than the fast correction interval.

9. A processor, characterized in that: Used to run a program, wherein the program is used to execute the method according to any one of claims 1 to 7 when being run.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method described in any one of claims 1 to 7 is implemented.

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