Method and control system for automatic soc calibration under large lithium battery energy storage thermal backup

Abstract

The present application relates to a kind of automatic calibration SOC under large lithium battery energy storage system thermal backup method and control system, the method is through the linkage control between IED, EMS, PMS, BMS, BMU five, automatically calibrates battery actual electric quantity, EMS is based on the neural network algorithm of batch data, fitting OCV-SOC characteristic curve, and update BMU electric quantity and characteristic curve, improve the SOC estimation accuracy of BMU during subsequent operation.The technical scheme of the present application realizes the depth SOC automatic calibration of energy storage system without outage state and the improvement of operation SOC estimation accuracy, improves the response accuracy of energy storage whole station power grid.

Description

Technical Field

[0001] This invention belongs to the field of control technology for large-scale lithium battery energy storage systems, and more specifically, relates to a method and control system for automatic SOC calibration under hot standby conditions of large-scale lithium battery energy storage. Background Technology

[0002] With the rapid development and widespread application of renewable energy, energy storage technology is playing an increasingly important role in the power system, and more and more megawatt-hour (MWH) energy storage systems are being deployed in the grid. Lithium-ion battery energy storage systems, as a highly efficient, reliable, and environmentally friendly energy storage solution, are widely used in grid peak shaving, frequency regulation, and backup power. Accurate estimation and management of the battery's state are crucial in energy storage systems.

[0003] The state of a battery is represented by its State of Charge (SOC), which is the percentage of energy currently stored relative to its full capacity. Accurately estimating the SOC is crucial for the stable operation of energy storage systems and the optimization of power generation plans. Currently, commonly used SOC estimation methods are mainly based on algorithms such as the open-circuit voltage method and Kalman filters. However, these methods have limitations, such as being affected by battery internal resistance, aging, self-discharge, and the uncertainty of process model parameters. Existing automatic SOC calibration technologies struggle to achieve automatic full-range calibration of energy storage systems in their hot standby state. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for automatic SOC calibration under large-scale lithium battery energy storage with thermal standby. This method achieves accurate SOC calibration of the battery by performing discharge and charge processes, combining real-time monitoring and analysis of current and voltage data, and utilizing an improved SOC estimation algorithm. This improves the reliability and performance of the energy storage system. This method enables accurate assessment of the battery's SOC and facilitates intelligent management and optimized operation of large-scale lithium battery energy storage systems.

[0005] The present invention adopts the following technical solution.

[0006] The first aspect of the present invention provides a method for automatic SOC calibration under large-scale lithium battery energy storage thermal standby conditions, comprising the following steps:

[0007] Step 1: Select the calibration battery stack in the SOC calibration interval, discharge the calibration battery stack at rated power, charge the other battery stacks in the SOC calibration interval, the total output power of the SOC calibration interval is 0, stop all charging and discharging after the calibration battery stack is completely discharged, and set the SOC value of the calibration battery stack to 0%.

[0008] Step 2: Charge the battery stack being calibrated in Step 1 at rated power, while discharging the remaining battery stacks in the SOC calibration interval. The total output power of the SOC calibration interval is 0. Stop all charging and discharging when the calibrated battery stack is fully charged. Set the SOC value of the calibrated battery stack to 100% and calibrate the SOH.

[0009] Step 3: Discharge the calibration battery stack being calibrated in Step 2 at rated power, charge the other battery stacks during the SOC calibration interval, and the total output power is 0. Discharge the calibration battery stack to the set SOC and stop all charging and discharging. Record its SOC, voltage and temperature data during the discharge process of the calibration battery stack.

[0010] Step 4: Charge the calibration battery stack being calibrated in Step 3 at rated power, while discharging the remaining battery stacks. The total output power is 0. Charge the calibration battery stack to the set SOC and stop all charging and discharging. Record its SOC, voltage and temperature data during the charging process of the calibration battery stack.

[0011] Step 5: Send the SOC, voltage, and temperature data recorded during the calibration of the battery stack in Steps 3 and 4 to EMS;

[0012] Step 6: Repeat steps 1 to 5 for the remaining battery stacks in the SOC calibration interval until all battery stacks in the SOC calibration interval have been calibrated; the energy management system will summarize and calculate the data to obtain the OCV correction curve and send it to the battery module management unit.

[0013] Preferably, step 1 includes:

[0014] Step 1.1: After starting the SOC calibration, the EMS sends the SOC calibration interval to the PMS and IED, the coordinating controller stops controlling the energy storage converter, and the charge and discharge control device selects PCSi as the calibration battery stack, where i is a natural number not greater than m.

[0015] Step 1.2: PMS stops controlling PCS1-PCSm, where m represents the number of PCS in the SOC calibration interval;

[0016] Step 1.3: IED controls PCSi to discharge at rated power, PCS other than PCSi to charge, and controls the total output power of PCS1-PCSm to be 0.

[0017] Preferably, step 2 includes:

[0018] Step 2.1: IED controls PCSi to charge at rated power, while the remaining PCS discharges, and the total output power of PCS1-PCSm is 0.

[0019] Step 2.2: After the battery stack corresponding to PCSi is fully charged, the IED controls PCS1-PCSm to stop charging and discharging; BMS1 calibrates the SOH and calibrates the SOC to 100%.

[0020] Preferably, step 3 includes:

[0021] Step 3.1: IED controls PCSi to discharge at rated power, while the remaining PCS are charged. The total output power of PCS1-PCSm is controlled to be 0. During the discharge process of the calibrated battery stack, its SOC, voltage and temperature data are recorded.

[0022] Step 3.2: After the battery stack corresponding to PCS1 is discharged to 10% SOC, the IED controls PCS1-PCSm to stop charging and discharging.

[0023] Preferably, step 4 includes:

[0024] Step 4.1: IED controls PCSi to charge at rated power, while the remaining PCS discharges, and controls the total output power of PCS1-PCSm to be 0.

[0025] Step 4.2: After the battery stack corresponding to PCS1 is charged to 90% SOC, the IED controls PCS1-PCSm to stop charging and discharging.

[0026] Preferably, between step 1 and step 2, between step 2 and step 3, and between step 3 and step 4, there is also a set period of rest.

[0027] Preferably, steps 1 to 6 are calibrated in a hot standby state, and the coordinating controller can terminate the SOC calibration at any time and resume control of the energy storage converter.

[0028] Preferably, in step 6, the EMS summarizes the offline calibration SOC, voltage, and temperature data, derives the optimal OCV correction curve based on the Kalman filter algorithm, and sends it to the BMU to update the BMS's online SOC verification algorithm.

[0029] A second aspect of the present invention provides a control system for automatic SOC calibration under thermal standby conditions in large-scale lithium battery energy storage, and a method for performing automatic SOC calibration under thermal standby conditions in large-scale lithium battery energy storage, comprising:

[0030] The energy storage system monitoring data network is used for data interaction between IED, PMS, BMS, PCS devices and EMS; after the SOC calibration is started, the EMS sends the SOC calibration interval to the PMS and IED, and coordinates the controller to stop controlling the energy storage converter.

[0031] Energy storage system control data network, used for control data exchange between IED, PMS, and PCS devices;

[0032] The IED is installed locally on the energy storage device and collects the grid connection point voltage and current of all PCS controlled by it. It calculates and controls the real-time output power of multiple PCS. During the calibration period, the IED controls the calibration battery stack to charge or discharge at the rated power, and the other battery stacks discharge or charge accordingly, with a total output power of 0.

[0033] Preferably, the energy storage system monitoring data network adopts the IEC 61850 or IEC 104 protocol;

[0034] The energy storage system control data network adopts the GOOSE protocol.

[0035] Compared with the prior art, the beneficial effects of the present invention include at least the following:

[0036] 1. The SOC calibration method provided by this invention is an automatic capacity calibration and SOC calibration, which does not require manual operation in the intermediate process, making the SOC calibration of energy storage system more efficient and faster; it greatly improves the accuracy of SOC calibration and the accuracy of SOC estimation in the later operation process, and improves the availability and reliability of large-scale energy storage power stations.

[0037] 2. The SOC calibration method provided by this invention ensures that the relevant equipment is in a hot standby state, and can respond to user requests to stop SOC calibration and start operation at any time without affecting the functional response and normal operation of large-scale energy storage power stations.

[0038] 3. The SOC calibration method provided by this invention is not targeted at any specific type of energy storage battery, has a wide range of applications, and has significant economic benefits. Attached Figure Description

[0039] Figure 1 This is a framework diagram of the control system used in the method for automatically calibrating the SOC of a large-scale lithium battery energy storage system under hot standby conditions, as described in this invention.

[0040] Figure 2 This is a flowchart of the method for automatically calibrating the State of Charge (SOC) of a large-scale lithium battery energy storage system under hot standby conditions, as described in this invention. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, other embodiments obtained by those skilled in the art without creative effort are all within the protection scope of this invention.

[0042] like Figure 1 , 2As shown, Embodiment 1 of the present invention provides a method for automatic SOC calibration under large-scale lithium battery energy storage thermal standby, comprising the following steps:

[0043] Step 1: Select the calibration battery stack in the SOC calibration interval. Discharge the calibration battery stack at rated power. Charge the other battery stacks in the SOC calibration interval. The total output power of the SOC calibration interval is 0. Stop all charging and discharging after the calibration battery stack is completely discharged. Set the SOC value of the calibration battery stack to 0%.

[0044] In a preferred but non-limiting embodiment of the present invention, step 1 includes:

[0045] Step 1.1: After starting the SOC calibration, the EMS sends the SOC calibration interval to the PMS and IED, the coordinating controller stops controlling the energy storage converter, and the charge and discharge control device selects a calibration battery stack.

[0046] Step 1.2: PMS stops controlling PCS1-PCSm, where m represents the number of PCS in the SOC calibration interval.

[0047] Step 1.3, taking PCS1 as the selected calibration battery stack as an example, the IED controls PCS1 to discharge at rated power, PCS2-PCSm to charge, and controls the total output power of PCS1-PCSm to be 0.

[0048] It is worth noting that the selection of PCS1 as the calibration battery stack is merely an example for ease of description and is not a limiting implementation. Those skilled in the art can select the calibration battery stack in any order during the SOC calibration interval.

[0049] During the calibration of the battery stacks at rated power discharge, all other PCS (Polymers) in the SOC calibration interval participate in charging. Preferably, but not limited to, the selection strategy considers the SOC state of each battery stack and rationally allocates the charging power to each stack. Those already calibrated continue to participate in subsequent calibration steps until all battery stacks are calibrated, at which point the entire process exits.

[0050] Step 1.4: After the battery stack corresponding to PCS1 is discharged, the IED controls PCS1-PCSm to stop charging and discharging; BMS1 is calibrated to SOC 0%.

[0051] More preferably, step 1 further includes step 1.5, after the IED controls PCS1-PCSm to stop charging and discharging, it is left to stand for a set time, preferably but not limited to 30 minutes.

[0052] Step 2: Charge the battery stack being calibrated in Step 1 at rated power, while discharging the remaining battery stacks in the SOC calibration interval. The total output power of the SOC calibration interval is 0. Stop all charging and discharging when the calibrated battery stack is fully charged. Set the SOC value of the calibrated battery stack to 100% and calibrate the SOH.

[0053] In a preferred but non-limiting embodiment of the present invention, step 2 includes:

[0054] Step 2.1: Continuing with PCS1 as the calibration battery stack as an example, the IED controls PCS1 to charge at its rated power, PCS2-PCSm to discharge, and the total output power of PCS1-PCSm is 0.

[0055] Step 2.2: After the battery stack corresponding to PCS1 is fully charged, the IED controls PCS1-PCSm to stop charging and discharging; BMS1 is calibrated to SOH and SOC to 100%.

[0056] More preferably, step 2 also includes step 2.3, after the IED controls PCS1-PCSm to stop charging and discharging, it is left to stand for a set time, preferably but not limited to 30 minutes.

[0057] Step 3: Discharge the calibration battery stack being calibrated in Step 2 at rated power, while charging the other battery stacks during the SOC calibration interval. The total output power is 0. Discharge the calibration battery stack until the set SOC is reached and then stop all charging and discharging. Record the SOC, voltage, and temperature data of the calibration battery stack during the discharge process.

[0058] In a preferred but non-limiting embodiment of the invention, the battery stack is calibrated to discharge to 10% SOC and then stop full charging and discharging.

[0059] In a preferred but non-limiting embodiment of the present invention, step 3 includes:

[0060] Step 3.1: Continue to select PCS1 as the calibration battery stack as an example. The IED controls PCS1 to discharge at rated power, PCS2-PCSm to charge, and controls the total output power of PCS1-PCSm to be 0. During the discharge process of the calibration battery stack, its SOC, voltage and temperature data are recorded.

[0061] Step 3.2: After the battery stack corresponding to PCS1 is discharged to 10% SOC, the IED controls PCS1-PCSm to stop charging and discharging.

[0062] More preferably, step 3 also includes step 3.3, after the IED controls PCS1-PCSm to stop charging and discharging, it is left to stand for a set time, preferably but not limited to 30 minutes.

[0063] Step 4: Charge the calibration battery stack being calibrated in Step 3 at rated power, while discharging the remaining battery stacks. The total output power is 0. Charge the calibration battery stack to the set SOC and stop all charging and discharging. Record its SOC, voltage, and temperature data during the charging process.

[0064] In a preferred but non-limiting embodiment of the invention, the battery stack is calibrated to charge to 90% SOC and then all charging and discharging is stopped.

[0065] In a preferred but non-limiting embodiment of the present invention, step 4 includes:

[0066] Step 4.1: The IED controls PCS1 to charge at its rated power, PCS2-PCSm to discharge, and controls the total output power of PCS1-PCSm to be 0.

[0067] Step 4.2: After the battery stack corresponding to PCS1 is charged to 90% SOC, the IED controls PCS1-PCSm to stop charging and discharging.

[0068] More preferably, step 4 also includes step 4.3, after the IED controls PCS1-PCSm to stop charging and discharging, it is left to stand for a set time, preferably but not limited to 30 minutes.

[0069] Step 5: Send the SOC, voltage, and temperature data recorded during the calibration of the battery stack in Steps 3 and 4 to EMS.

[0070] Step 6: Repeat steps 1 to 5 for the remaining battery stacks in the SOC calibration interval until all battery stacks in the SOC calibration interval have been calibrated; the energy management system will summarize and calculate the data to obtain the OCV correction curve and send it to the battery module management unit.

[0071] In a preferred but non-limiting embodiment of the present invention, if necessary, the coordination controller can terminate the SOC calibration at any time and resume control of the energy storage converter.

[0072] In a preferred but non-limiting embodiment of the present invention, the EMS summarizes the offline calibration SOC, voltage and temperature data, derives the optimal OCV correction curve based on the Kalman filter algorithm, and sends it to the BMU to update the BMS's online SOC verification algorithm.

[0073] It is worth noting that, unlike the model-based calibration in the prior art, the core concept of this invention includes at least the following: This invention calibrates based on big data in a hot standby state, without affecting the operation of the entire site. If necessary, the PMS can terminate the SOC calibration at any time and restore control over PCS1-PCSm.

[0074] like Figure 2As shown, Embodiment 2 of the present invention provides a control system used in the method for automatic SOC calibration under large-scale lithium battery energy storage with thermal standby. Here, number 2 represents the energy storage system monitoring data network, used for data interaction between IED, PMS, BMS, PCS devices and EMS, and can adopt IEC 61850 or IEC 104 protocols; number 4 represents the energy storage system control data network, used for rapid control data interaction between IED, PMS, and PCS devices, and can adopt the GOOSE protocol; the IED is installed locally on the energy storage device and collects the grid connection point voltage and current of all PCS controlled by it, calculating and controlling the real-time output power of multiple PCS.

[0075] The meanings of the terms and figures are as follows:

[0076] 1: EMS, Energy Management System for Energy Storage Power Stations, used to monitor energy storage power stations;

[0077] 2: Energy storage power station monitoring data network, used for monitoring data exchange between EMS, IED, PMS, BMS, and PCS;

[0078] 3: PMS, the total station coordination controller of the energy storage power station, is used to control the entire PCS of the energy storage station;

[0079] 4: Energy storage power station control data network, used for rapid exchange of power control data between IED, PMS, and PCS;

[0080] 5: BMS, Battery Management System, used to monitor and protect the battery system;

[0081] 6: PCS, energy storage converter, used for AC / DC conversion;

[0082] 7: BMS and PCS data interaction network, used for data interaction between BMS and PCS;

[0083] 8: BCMU, Battery Cluster Management Unit, used to monitor and protect battery clusters;

[0084] 9: BMU, Battery Module Management Unit, used to monitor and protect the battery module;

[0085] 10: IED, a device for controlling the charging and discharging of multiple PCS, used to control the charging and discharging of multiple PCS.

[0086] This disclosure can be a system, method, and / or computer program product. A computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for causing a processor to implement various aspects of this disclosure.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A method for automatic SOC calibration under thermal standby conditions for large-scale lithium battery energy storage, characterized in that, Includes the following steps: Step 1: Select the calibration battery stack in the SOC calibration interval. Discharge the calibration battery stack at rated power, while the other battery stacks in the SOC calibration interval are charged. The total output power of the SOC calibration interval is 0. Stop all charging and discharging after the calibration battery stack is completely discharged, and set the SOC value of the calibration battery stack to 0%. Step 2: Charge the battery stack being calibrated in Step 1 at rated power, while discharging the remaining battery stacks in the SOC calibration interval. The total output power of the SOC calibration interval is 0. Stop all charging and discharging when the calibrated battery stack is fully charged. Set the SOC value of the calibrated battery stack to 100% and calibrate the SOH. Step 3: Discharge the calibration battery stack being calibrated in Step 2 at rated power, charge the other battery stacks during the SOC calibration interval, and the total output power is 0. Discharge the calibration battery stack to the set SOC and stop all charging and discharging. Record its SOC, voltage and temperature data during the discharge process of the calibration battery stack. Step 4: Charge the calibration battery stack being calibrated in Step 3 at rated power, while discharging the remaining battery stacks. The total output power is 0. Charge the calibration battery stack to the set SOC and stop all charging and discharging. Record its SOC, voltage and temperature data during the charging process of the calibration battery stack. Step 5: Send the SOC, voltage, and temperature data recorded during the calibration of the battery stack in Steps 3 and 4 to EMS; Step 6: Repeat steps 1 to 5 for the remaining battery stacks in the SOC calibration interval until all battery stacks in the SOC calibration interval have been calibrated; the energy management system will summarize and calculate the data to obtain the OCV correction curve and send it to the battery module management unit. Steps 1 to 6 are calibrated in hot standby mode. The coordinating controller can terminate the SOC calibration at any time and resume control of the energy storage converter.

2. The method for automatic SOC calibration under thermal standby conditions for large-scale lithium battery energy storage as described in claim 1, characterized in that: Step 1 includes: Step 1.1: After starting the SOC calibration, the EMS sends the SOC calibration interval to the PMS and IED, the coordinating controller stops controlling the energy storage converter, and the charge and discharge control device selects PCSi as the calibration battery stack, where i is a natural number not greater than m. Step 1.2: PMS stops controlling PCS1-PCSm, where m represents the number of PCS in the SOC calibration interval; Step 1.3: IED controls PCSi to discharge at rated power, PCS other than PCSi to charge, and controls the total output power of PCS1-PCSm to be 0.

3. The method for automatic SOC calibration under thermal standby conditions for large-scale lithium battery energy storage as described in claim 2, characterized in that: Step 2 includes: Step 2.1: IED controls PCSi to charge at rated power, while the remaining PCS discharges, and the total output power of PCS1-PCSm is 0. Step 2.2: After the battery stack corresponding to PCSi is fully charged, IED controls PCS1-PCSm to stop charging and discharging; BMS1 calibrates SOH and calibrates SOC to 100%.

4. The method for automatic SOC calibration under thermal standby conditions for large-scale lithium battery energy storage as described in claim 3, characterized in that: Step 3 includes: Step 3.1: IED controls PCSi to discharge at rated power, while the remaining PCS are charged. The total output power of PCS1-PCSm is controlled to be 0. During the discharge process of the calibrated battery stack, its SOC, voltage and temperature data are recorded. Step 3.2: After the battery stack corresponding to PCS1 is discharged to 10% SOC, the IED controls PCS1-PCSm to stop charging and discharging.

5. The method for automatic SOC calibration under thermal standby conditions for large-scale lithium battery energy storage as described in claim 4, characterized in that: Step 4 includes: Step 4.1: IED controls PCSi to charge at rated power, while the remaining PCS discharges, and controls the total output power of PCS1-PCSm to be 0. Step 4.2: After the battery stack corresponding to PCS1 is charged to 90% SOC, the IED controls PCS1-PCSm to stop charging and discharging.

6. The method for automatic SOC calibration under thermal standby conditions for large-scale lithium battery energy storage as described in claim 4, characterized in that: Between step 1 and step 2, between step 2 and step 3, and between step 3 and step 4, there is also a set period of rest.

7. The method for automatic SOC calibration under thermal standby conditions for large-scale lithium battery energy storage as described in claim 4, characterized in that: In step 6, the EMS summarizes the offline calibration SOC, voltage, and temperature data, derives the optimal OCV correction curve based on the Kalman filter algorithm, and sends it to the BMU to update the BMS's online SOC verification algorithm.

8. A control system for automatic SOC calibration under thermal standby conditions in large-scale lithium battery energy storage, executing a method for automatic SOC calibration under thermal standby conditions in large-scale lithium battery energy storage as described in any one of claims 1-7, characterized in that, include: Energy storage system monitoring data network, used for data exchange between IED, PMS, BMS, PCS devices and EMS; After initiating SOC calibration, EMS sends the SOC calibration interval to PMS and IED, and the coordinating controller stops controlling the energy storage converter. Energy storage system control data network, used for control data exchange between IED, PMS, and PCS devices; The IED is installed locally on the energy storage device and collects the grid connection point voltage and current of all PCS controlled by it. It calculates and controls the real-time output power of multiple PCS. During the calibration period, the IED controls the calibration battery stack to charge or discharge at the rated power, and the other battery stacks discharge or charge accordingly, with a total output power of 0.

9. A control system for automatic SOC calibration under thermal standby conditions in large-scale lithium battery energy storage as described in claim 8, characterized in that: The energy storage system monitoring data network adopts the IEC 61850 or IEC 104 protocol; The energy storage system control data network adopts the GOOSE protocol.

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