A soc multi-parameter cooperative correction method for power frequency modulation energy storage battery system

Abstract

The application discloses a SOC multi-parameter cooperative correction method for a power frequency-regulating energy storage battery system, which comprises the following steps: collecting voltage, current and internal resistance data of each battery pack in the energy storage battery system in real time, and correcting a basic SOC value calculated based on a current integration method by a preset step length only when the SOC is lower than a first threshold value or higher than a second threshold value based on an internal resistance-voltage joint correction model; meanwhile, a cluster linkage mechanism is established, and when the single cell voltage of any parallel battery pack is lower than a preset linkage threshold value, the SOCs of all the parallel battery packs are uniformly calibrated to a real SOC value corresponding to the lowest voltage pack. The application is based on multi-parameter cooperative correction and cluster linkage calibration, effectively compensates for the cumulative error of the current integration, suppresses the expansion of the SOC difference between the parallel battery packs, and significantly improves the consistency of the energy storage battery system.

Description

Technical Field

[0001] This application belongs to the field of power energy storage system control technology, specifically relating to a method for collaborative correction of SOC multiple parameters in a power frequency regulation energy storage battery system. Background Technology

[0002] In the field of power frequency regulation energy storage, to meet the needs of rapid grid response, energy storage systems must be capable of full-power charging and discharging at any time. Existing energy storage sites generally adopt a hierarchical architecture of "transformer-container-PCS-battery cabinet," with a large number of battery packs operating in parallel. The remaining battery charge (State of Charge, SOC) is a key parameter for the system's power distribution and charge / discharge management.

[0003] Currently, the current integration method is commonly used for SOC calculation. However, this method has inherent drawbacks: First, the measurement error of the current sensor accumulates over time, causing the calculated SOC value to deviate from the true value; second, differences in the State of Health (SOH) between battery packs further amplify this error. In power frequency regulation applications, the system often operates in a plateau region around 50% SOC, where voltage changes are gradual, making it impossible to effectively calibrate the SOC using voltage. This leads to a continuous accumulation of SOC errors and a deterioration in the SOC consistency among parallel battery packs.

[0004] The accuracy and consistency of State of Charge (SOC) directly affect the system's power output capability. When the calculated SOC falls into a high range (e.g., >90%) or a low range (e.g., <10%) due to errors, the Battery Management System (BMS) will trigger unnecessary power limiting, causing the system to be unable to stably output full power according to scheduling instructions, severely affecting the response speed and stability of power frequency regulation services. Furthermore, existing technologies rely on a single power limiting mechanism, primarily depending on SOC and temperature, lacking verification of the battery's actual physical state, resulting in a high false trigger rate. Summary of the Invention

[0005] The purpose of this invention is to provide a method for collaborative correction of multiple parameters of SOC in a power frequency regulation energy storage battery system. This method is used to solve the technical problem that the accumulation of SOC calculation errors and poor consistency in the prior art lead to the limitation of the system's full-power operation.

[0006] To achieve the above objectives, the present invention provides a method for coordinated correction of multiple parameters of state of charge (SOC) in a power frequency regulation energy storage battery system, the method comprising the following steps: S100: Real-time acquisition of voltage, current and internal resistance data of each battery pack in the energy storage battery system; S200, calculates the basic SOC value of each battery pack based on the current integration method; S300: Determine the range of the base SOC value of each battery pack. If the base SOC value of the battery pack is lower than the first threshold, enter the discharge correction mode; if the base SOC value of the battery pack is higher than the second threshold, enter the charging correction mode. The first threshold is less than the second threshold, the first threshold is 20%, and the second threshold is 80%. The discharge correction mode is specifically: calculate the corresponding correction voltage based on the measured minimum voltage, real-time internal resistance, and current of the current battery pack. If the measured minimum voltage is greater than the correction voltage, the base SOC value is corrected upward by a preset step size. The charging correction mode is specifically: calculate the corresponding correction voltage based on the measured maximum voltage, real-time internal resistance, and current of the current battery pack. If the measured maximum voltage is less than the correction voltage, the base SOC value is corrected downward by a preset step size. S400, outputs the corrected SOC value.

[0007] Furthermore, in step S300, the calculation model for the corrected voltage is: V real = V SOC + I*R, where V real To correct the voltage, V SOC I is the standard open-circuit voltage corresponding to the current base SOC value, I is the current current, and R is the real-time internal resistance.

[0008] Furthermore, the internal resistance data is obtained in real time by DC discharge method and is dynamically updated based on the initial internal resistance of the battery pack, SOH decay characteristics and periodic calibration results.

[0009] Furthermore, the preset step size in step S300 is 1% SOC.

[0010] Furthermore, it also includes an inter-cluster linkage calibration step: The voltage of individual cells in all parallel battery packs is monitored in real time. When the voltage of any individual cell is lower than the preset linkage voltage threshold, linkage calibration is triggered. The linkage calibration specifically includes: taking the lowest voltage battery pack that triggers the linkage as a reference and determining its true SOC value, and then uniformly calibrating the SOC value of all parallel battery packs to the true SOC value.

[0011] Furthermore, it also includes a dual power-limiting verification step: When the base SOC value is greater than 80%, the charging power limit prediction is triggered to determine whether the maximum voltage of the current single cell exceeds the voltage threshold calculated based on the current dynamic SOH and current. If it does not exceed the threshold, the charging power limit is lifted. When the base SOC value is less than 20%, the discharge power limit prediction is triggered to determine whether the minimum voltage of the current single cell is lower than the voltage threshold calculated based on the current dynamic SOH and current. If it is not lower than the threshold, the discharge power limit is lifted.

[0012] To achieve the above objectives, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the cooperative correction method as described above.

[0013] To achieve the above objectives, the present invention also provides a power frequency regulation energy storage battery system, including a battery pack and a BMS battery management system. The BMS battery management system includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the aforementioned cooperative correction method.

[0014] Compared with the prior art, the present invention has the following beneficial technical effects: (1) This invention effectively compensates for the cumulative error of current integration by coordinating the correction of multiple parameters such as voltage, internal resistance and current, and only performs calibration in the SOC sensitive range. At the same time, the inter-cluster linkage mechanism fundamentally suppresses the expansion of SOC difference between parallel groups and significantly improves system consistency.

[0015] (2) By extending the effective operating range of SOC to 20%-80% of the actual range and combining it with dual power limit verification of "SOC + voltage", this invention completely avoids unnecessary power limits caused by SOC calculation errors, ensuring that the system can stably respond to the full power requirements of power frequency regulation.

[0016] (3) This invention is a pure software algorithm optimization, which does not require modification of the existing hardware architecture and is easy to deploy in the existing power frequency regulation energy storage system; at the same time, it supports dynamic adjustment of parameters according to different battery types and SOH states, and has strong adaptability.

[0017] (4) The collaborative correction method provided by the present invention effectively avoids the risk of overcharging and over-discharging of the battery by correcting the constraints of frequency and amplitude, dual power limit verification and inter-cluster linkage protection. The parameter dynamic update mechanism can adapt to the battery aging characteristics and ensure the operating accuracy and reliability of the system throughout its entire life cycle. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a flowchart of a method for collaborative correction of multiple parameters of state of charge (SOC) in a power frequency regulation energy storage battery system according to the present invention; Figure 2This is a flowchart of the interval correction step in an embodiment of the present invention; Figure 3 This is a flowchart of the inter-cluster linkage calibration step in an embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and technical effects of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings, multiple embodiments, and comparative examples. In the following description, the same components are referred to by the same reference numerals.

[0021] Example 1 This embodiment provides a method for collaborative correction of SOC multiple parameters in a power frequency regulation energy storage battery system. It is applicable to typical power frequency regulation energy storage site architectures, such as: a typical energy storage site includes: 10 transformers, each transformer connected to 6 containers; each container is equipped with 2 sets of PCS (each set with a maximum output of 700kW), each set of PCS is connected to 4 sets of parallel battery cabinets, and the system needs to output 1.4MW of power at any time to meet the frequency regulation requirements.

[0022] like Figure 1 As shown, the method includes the following steps: S100: Real-time acquisition of voltage, current and internal resistance data of each battery pack in the energy storage battery system; Specifically, this step involves real-time acquisition of voltage, current, and internal resistance data for each battery pack through the Battery Management System (BMS), where: Voltage data includes: the maximum voltage (Vmax), minimum voltage (Vmin) of each battery pack and the voltage distribution of individual cells, as well as pre-stored key voltage thresholds, such as the open-circuit voltage corresponding to 20% SOC and the open-circuit voltage corresponding to 80% SOC. The internal resistance data includes: using the DC discharge method, the DC internal resistance R of the battery pack is calculated in real time based on the voltage drop and current change at the moment of battery discharge. To ensure accuracy, the internal resistance value can be dynamically updated by combining the initial internal resistance of the battery at the time of manufacture, the SOH decay curve, and the periodic calibration results to ensure the accuracy of R. Simultaneously, data such as battery pack SOH, runtime, and cycle count are collected to provide a basis for dynamic adjustment of subsequent correction parameters.

[0023] S200, calculates the basic SOC value of each battery pack based on the current integration method; Specifically, this step involves using the traditional ampere-hour integration method to calculate the base SOC value of each battery pack in real time based on the collected current data and the initial SOC value. This base SOC value will accumulate errors over time.

[0024] S300: Determine the range of the base SOC value of each battery pack. If the base SOC value of the battery pack is lower than the first threshold, enter the discharge correction mode; if the base SOC value of the battery pack is higher than the second threshold, enter the charging correction mode. The first threshold is 20%, and the second threshold is 80%. Specifically, the discharge correction mode calculates the corresponding correction voltage based on the measured minimum voltage, real-time internal resistance, and current of the current battery pack. If the measured minimum voltage is greater than the correction voltage, the base SOC value is corrected upwards by a preset step size until the base SOC value reaches the first threshold or the number of corrections reaches a preset value. Specifically, the charging correction mode calculates the corresponding correction voltage based on the measured maximum voltage, real-time internal resistance, and current of the current battery pack. If the measured maximum voltage is less than the correction voltage, the base SOC value is corrected downwards by a preset step size until the base SOC value reaches the second threshold or the number of corrections reaches a preset value. In this step, if the base SOC value is between 20% and 80%, it is in the voltage plateau region and no correction is performed; if the base SOC value is less than 20% (first threshold), it enters the discharge correction mode; if the base SOC value is greater than 80% (second threshold), it enters the charging correction mode. like Figure 2 As shown, the specific steps of the discharge correction mode are as follows: (1) Obtain the measured minimum voltage V of the current battery pack min Real-time internal resistance R, current current I; (2) Based on the basic SOC value, look up the table (specifically, look up the OCV table of the cell manufacturer corresponding to the current battery pack) to obtain the standard open circuit voltage V corresponding to the current battery pack. SOC ; (3) Calculate the corrected voltage V of the current battery pack according to the corrected voltage calculation model. real = V SOC + I*R; (4) Determine if V min Greater than V real This indicates that the actual voltage of the battery pack is higher than the model prediction value, which means that the actual SOC of the battery pack is higher than the current calculated value (the integral SOC is too low). At this time, the base SOC value is corrected upward by a preset step size (e.g., 1% SOC). This correction process can be carried out iteratively until the condition is not met or the upper limit of the number of corrections is reached.

[0025] The specific steps for the charging correction mode are as follows: (1) Obtain the measured maximum voltage V of the current battery pack max Real-time internal resistance R, current current I; (2) Based on the base SOC value, look up the table to obtain the standard open-circuit voltage V corresponding to the current battery pack. SOC ; (3) Calculate the corrected voltage V of the current battery pack. real = V SOC + I*R; (4) Determine if V max Less than V real This indicates that the actual voltage of the battery pack is lower than the model prediction value, which means that the actual SOC of the battery pack is lower than the current calculated value (the integral SOC is too high). At this time, the base SOC value is corrected downward by a preset step size (e.g., 1% SOC). This correction process can be carried out iteratively until the condition is not met or the upper limit of the number of corrections is reached.

[0026] S310 also includes inter-cluster linkage calibration, such as Figure 3 As shown, the specific steps are as follows: S311. Real-time monitoring of the voltage of individual cells in all parallel battery packs; S312. When it is detected that the voltage of a single cell in any group of battery packs is ≤ 3.1V (linkage voltage threshold), the inter-cluster linkage mechanism is triggered. 3.1V is chosen as the linkage voltage threshold because near this voltage point, there is a strong correlation between SOC and voltage, which can accurately determine the remaining capacity of the battery. S313. Using the lowest voltage battery pack that triggers the linkage (i.e., the pack with the lowest voltage) as a reference, determine its true SOC value based on its voltage value (e.g., by looking up a table). S314. Force the SOC values ​​of all parallel battery packs displayed in the Battery Management System (BMS) to be uniformly calibrated to the true SOC values ​​of the reference group (lowest voltage battery pack). This can prevent high SOC groups from performing unwanted cross-charging to low SOC groups during subsequent charging and discharging processes, thus suppressing the expansion of SOC differences from the source.

[0027] S320 also includes dual power limit verification. This step is used to prevent incorrect power limiting due to SOC calculation errors. When the SOC is in the boundary region, a secondary verification is performed in conjunction with the voltage, as follows: When the calculated base SOC value is greater than 80%, the system prepares to limit the charging power. Before limiting the power, a second judgment is made: check whether the maximum voltage of the current single cell exceeds the voltage threshold calculated based on the dynamic SOH and the current current. If the actual maximum voltage does not exceed the voltage threshold, it means that the battery still has charging space and the current SOC value may be too high. Therefore, the charging power limit is lifted. When the calculated base SOC value is less than 20%, the system prepares to limit the discharge power. Before limiting the power, a second judgment is made: check whether the minimum voltage of the current single cell is lower than the voltage threshold calculated based on the dynamic SOH and the current current. If the actual minimum voltage is not lower than the voltage threshold, it means that the battery still has discharge capacity and the current SOC value may be too low. Therefore, the discharge power limit is lifted.

[0028] S400 outputs the corrected SOC value, which is used for the system's charging and discharging strategy, power allocation, and data display.

[0029] Example 2 As an alternative to the present invention, the corrected voltage calculation model in step S300 can be replaced by a Kalman filter algorithm. Kalman filtering can fuse multi-dimensional data such as voltage, current, and temperature in real time and make optimal estimates of the system state (SOC), which can further improve the SOC correction accuracy in dynamic frequency response scenarios. This alternative also falls within the protection scope of the present invention.

[0030] The above provides a detailed description of a multi-parameter collaborative correction method for the State of Charge (SOC) of a power frequency regulation energy storage battery system. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are merely for the purpose of helping to understand the core ideas of this application. It should be noted that those skilled in the art can make various improvements and modifications to this application without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A method for coordinated correction of multiple parameters of state of charge (SOC) in a power frequency regulation energy storage battery system, characterized in that, The method includes the following steps: S100: Real-time acquisition of voltage, current and internal resistance data of each battery pack in the energy storage battery system; S200, calculates the basic SOC value of each battery pack based on the current integration method; S300: Determine the range of the base SOC value of each battery pack. If the base SOC value of the battery pack is lower than the first threshold, enter the discharge correction mode; if the base SOC value of the battery pack is higher than the second threshold, enter the charging correction mode. Specifically, the first threshold is less than the second threshold. The discharge correction mode is as follows: calculate the corresponding correction voltage based on the measured minimum voltage, real-time internal resistance, and current of the current battery pack. If the measured minimum voltage is greater than the correction voltage, the base SOC value is corrected upward by a preset step size. The charging correction mode is as follows: calculate the corresponding correction voltage based on the measured maximum voltage, real-time internal resistance, and current of the current battery pack. If the measured maximum voltage is less than the correction voltage, the base SOC value is corrected downward by a preset step size. S400, outputs the corrected SOC value.

2. The collaborative correction method according to claim 1, characterized in that, In step S300, the calculation model for the corrected voltage is: V real = V SOC + I*R, where V real To correct the voltage, V SOC I is the standard open-circuit voltage corresponding to the current base SOC value, I is the current current, and R is the real-time internal resistance.

3. The collaborative correction method according to claim 1, characterized in that, The first threshold is 20%, and the second threshold is 80%.

4. The collaborative correction method according to claim 1, characterized in that, The internal resistance data is obtained in real time by DC discharge method and is dynamically updated based on the initial internal resistance of the battery pack, SOH decay characteristics and periodic calibration results.

5. The collaborative correction method according to claim 1, characterized in that, The preset step size in step S300 is 1% SOC.

6. The collaborative correction method according to claim 1, characterized in that, It also includes inter-cluster linkage calibration steps: The voltage of individual cells in all parallel battery packs is monitored in real time. When the voltage of any individual cell is lower than the preset linkage voltage threshold, linkage calibration is triggered. The linkage calibration specifically includes: taking the lowest voltage battery pack that triggers the linkage as a reference and determining its true SOC value, and then uniformly calibrating the SOC value of all parallel battery packs to the true SOC value.

7. The collaborative correction method according to claim 6, characterized in that, The linkage voltage threshold is 3.1V.

8. The collaborative correction method according to claim 1, characterized in that, It also includes a dual power-limiting verification step: When the base SOC value is greater than 80%, the charging power limit prediction is triggered to determine whether the maximum voltage of the current single cell exceeds the voltage threshold calculated based on the current dynamic SOH and current. If it does not exceed the threshold, the charging power limit is lifted. When the base SOC value is less than 20%, the discharge power limit prediction is triggered to determine whether the minimum voltage of the current single cell is lower than the voltage threshold calculated based on the current dynamic SOH and current. If it is not lower than the threshold, the discharge power limit is lifted.

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

10. A power frequency regulation energy storage battery system, comprising a battery pack and a BMS battery management system, characterized in that, The BMS battery management system includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the cooperative correction method as described in any one of claims 1 to 8.

Images