CN117761555A - Automatic SOC calibration method and control system under large lithium battery energy storage hot standby - Google Patents

Abstract

The invention relates to a method and a control system for automatically calibrating SOC under hot standby of a large lithium battery energy storage system, wherein the method is used for automatically calibrating the actual electric quantity of a battery through linkage control between IED, EMS, PMS, BMS, BMU, an EMS (energy management system) fits an OCV-SOC characteristic curve based on a neural network algorithm of batch data, and updates the electric quantity and the characteristic curve of a BMU (battery management unit), so that the SOC estimation precision of the BMU in the subsequent operation period is improved. According to the technical scheme, the automatic deep SOC calibration and the operation SOC estimation precision improvement of the energy storage system in the continuous operation state are realized, and the response accuracy of the energy storage whole-station power grid is improved.

Description

Automatic SOC calibration method and control system under large lithium battery energy storage hot standby

Technical Field

The invention belongs to the technical field of control of energy storage systems of large lithium batteries, and particularly relates to a method and a control system for automatic SOC calibration under the standby of energy storage heat of a large lithium battery.

Background

With the rapid development and popularization of renewable energy sources, energy storage technology plays an increasingly important role in power systems, and more hundred megawatt-hour energy storage systems are put into power grid application. The lithium battery energy storage system is used as an efficient, reliable and environment-friendly energy storage solution and is widely applied to the fields of peak regulation and valley filling of a power grid, frequency regulation and control, standby power supply and the like. In energy storage systems, accurate estimation and management of the state of the battery is critical.

The State of a battery is represented by its State of Charge (SOC), i.e., the percentage of the battery's currently stored energy relative to its full capacity. Accurate estimation of the SOC of the battery is important for stable operation of the energy storage system and optimization of the power generation schedule. At present, commonly used SOC estimation methods are mainly based on algorithms such as an open-circuit voltage method and a Kalman filter, but the methods have some limitations, such as problems of influence of internal resistance, aging and self-discharge of a battery, uncertainty of parameters of a process model and the like. The existing automatic calibration SOC technology is difficult to realize the automatic full-range calibration of the hot standby state of the energy storage system.

Disclosure of Invention

In order to solve the defects in the prior art, the invention provides the method for automatically calibrating the SOC of the large lithium battery under the standby of energy storage heat. By the method, the SOC of the battery can be accurately estimated, and intelligent management and optimized operation of the large-scale lithium battery energy storage system can be realized.

The invention adopts the following technical scheme.

The first aspect of the invention provides a method for automatic SOC calibration under a large lithium battery energy storage hot standby, which comprises the following steps:

step 1, selecting a calibrated cell stack in an SOC calibration interval, discharging the calibrated cell stack with rated power, charging other cell stacks in the SOC calibration interval, wherein the total output power of the SOC calibration interval is 0, stopping all charging and discharging after the electric quantity of the calibrated cell stack is emptied, and setting the SOC value of the calibrated cell stack to 0%;

step 2, charging the cell stack calibrated in the step 1 with rated power, discharging the rest cell stacks in an SOC calibration interval, stopping all charging and discharging until the electric quantity of the calibrated cell stack is full, calibrating the SOC value of the cell stack to be 100%, and calibrating SOH;

step 3, discharging the calibrated battery stack calibrated in the step 2 at rated power, charging other battery stacks in an SOC calibration interval, wherein the total output power is 0, discharging the calibrated battery stack until the set SOC stops all charging and discharging, and recording SOC, voltage and temperature data of the calibrated battery stack in the discharging process;

step 4, charging the calibrated battery stack calibrated in the step 3 with rated power, discharging the rest battery stacks, wherein the total output power is 0, charging the calibrated battery stack to a set SOC, stopping all charging and discharging, and recording SOC, voltage and temperature data of the calibrated battery stack in the charging process;

step 5, sending the SOC, voltage and temperature related data recorded in the process of the calibrated battery stack calibrated in the step 3 and the step 4 to an EMS;

step 6, repeating the steps 1 to 5 for the rest of the battery stacks in the SOC calibration interval until all the battery stacks in the SOC calibration interval are calibrated; the energy management system gathers and calculates the data to obtain an OCV correction curve and sends the OCV correction curve to the battery module management unit.

Preferably, step 1 comprises:

step 1.1, after starting SOC calibration, EMS sends an SOC calibration interval to PMS and IED, a coordination controller stops controlling an energy storage converter, a charge-discharge control device selects PCSi as a calibration cell stack, and i is a natural number not greater than m;

step 1.2, the PMS stops controlling the PCS1-PCSm, and m represents the number of PCS in the SOC calibration interval;

in step 1.3, the IED controls PCSi to discharge at rated power, PCS other than PCSi to charge, and controls PCS1-PCSm total output power to 0.

Preferably, step 2 comprises:

step 2.1, the IED controls PCSi to charge at rated power, the rest PCS discharges, and the total output power of PCS1-PCSm is 0;

step 2.2, after the PCSi is fully charged corresponding to the battery stack electric quantity, the IED controls the PCS1-PCSm to stop charging and discharging; BMS1 calibrates SOH and calibrates SOC 100%.

Preferably, step 3 comprises:

step 3.1, the IED controls PCSi to discharge at rated power, the rest PCS charges, controls the total output power of PCS1-PCSm to be 0, and records SOC, voltage and temperature data in the process of calibrating the discharging of the battery stack;

and 3.2, after the PCS1 corresponding battery stack is discharged to the SOC of 10%, the IED controls the PCS1-PCSm to stop charging and discharging.

Preferably, step 4 comprises:

step 4.1, the IED controls PCSi to charge at rated power, the rest PCS discharges, and the total output power of PCS1-PCSm is controlled to be 0;

and 4.2, after the PCS1 corresponding battery stack is charged to the SOC of 90%, the IED controls the PCS1-PCSm to stop charging and discharging.

Preferably, between step 1 and step 2, between step 2 and step 3, between step 3 and step 4, a rest for a set period of time is further included.

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

Preferably, in step 6, the EMS collects the offline calibration SOC, voltage and temperature data, obtains an optimal OCV correction curve based on a kalman filter algorithm, and issues an online SOC calibration algorithm to the BMU update BMS.

The second aspect of the present invention provides a control system for automatic SOC calibration in a hot standby state of energy storage of a large lithium battery, and the method for performing automatic SOC calibration in a hot standby state of energy storage of a large lithium battery, comprising:

the energy storage system monitors a data network for data interaction between IED, PMS, BMS, PCS equipment and the EMS; after starting SOC calibration, the EMS transmits an SOC calibration interval to the PMS and the IED, and the coordination controller stops controlling the energy storage converter;

the energy storage system control data network is used for controlling data interaction among IED, PMS, PCS devices;

the IED is installed on the site of the energy storage equipment, acquires the voltage and current of grid-connected points of all PCSs controlled by the IED, and calculates and controls the real-time output power of a plurality of PCSs; during calibration, the IED controls the calibrated battery stack to charge or discharge at rated power, and the rest battery stacks correspondingly discharge or charge, so that the total output power is 0.

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

the energy storage system controls the data network to adopt GOOSE protocol.

Compared with the prior art, the invention has the beneficial effects that at least:

1. the SOC calibration method provided by the invention is automatic capacity calibration and SOC calibration, and the middle process does not need manual operation, so that the SOC calibration of the energy storage system is more efficient and faster; the SOC calibration precision and the SOC estimation accuracy in the later running process are greatly improved, and the availability and reliability of the large-scale energy storage power station are improved.

2. The SOC calibration method provided by the invention ensures that related equipment is in a hot standby state, can respond to the requirement of a user at any time to stop SOC calibration and put into operation, and does not influence the functional response and normal operation of the large-scale energy storage power station.

3. The SOC calibration method provided by the invention is not specific to a specific energy storage battery type, has a wide application range and has remarkable economic benefit.

Drawings

FIG. 1 is a block diagram of a control system used in the method of the present invention for automatically calibrating SOC in hot standby of a large lithium battery energy storage system;

FIG. 2 is a flow chart of a method for automatically calibrating SOC in hot standby of a large lithium battery energy storage system according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. The embodiments described herein are merely some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art without making any inventive effort, are within the scope of the present invention.

As shown in fig. 1 and 2, embodiment 1 of the present invention provides a method for automatic SOC calibration under hot standby of energy storage of a large lithium battery, including the following steps:

step 1, selecting a calibrated battery stack in an SOC calibration interval, discharging the calibrated battery stack with rated power, charging other battery stacks in the SOC calibration interval, and stopping all charging and discharging until the electric quantity of the calibrated battery stack is emptied, wherein the SOC value of the calibrated battery stack is set to 0%.

In a preferred but non-limiting embodiment of the present invention, step 1 comprises:

step 1.1, after starting SOC calibration, the EMS sends an SOC calibration interval to the PMS and the IED, the coordination controller stops controlling the energy storage converter, and the charge-discharge control device selects one calibration cell stack.

Step 1.2, PMS stops control of PCS1-PCSm, m represents the number of PCS in the SOC calibration interval.

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

it is noted that PCS1 selection of PCS1 as an example of a calibration stack is merely an illustrative but non-limiting implementation that is convenient for presentation, and one skilled in the art may select a calibration stack in any order during the SOC calibration interval.

During the period when the calibrated stacks are discharged at rated power, all PCS in the SOC calibration interval participate in charging, and the selection strategy preferably but not exclusively considers the SOC state of each stack, so that the charging power of each stack is reasonably distributed. And continuing to participate in the subsequent calibration step after the calibration until the calibration of all the cell stacks is completed, and exiting the whole.

Step 1.4, after the battery stack electric quantity corresponding to the PCS1 is exhausted, the IED controls the PCS1-PCSm to stop charging and discharging; BMS1 calibrates SOC0%.

Further preferably, step 1 further comprises step 1.5, and the IED is allowed to stand for a set period of time, preferably but not limited to 30 minutes, after the PCS1-PCSm is controlled to stop charging and discharging.

And 2, charging the cell stack calibrated in the step 1 at rated power, discharging the rest cell stacks in an SOC calibration interval, stopping all charging and discharging after the electric quantity of the calibrated cell stack is full, calibrating the SOC value of the cell stack to 100%, and calibrating SOH.

In a preferred but non-limiting embodiment of the present invention, step 2 comprises:

step 2.1, continuing to select PCS1 as the calibration stack for example, IED controls PCS1 to charge at rated power, PCS2-PCSm to discharge, and PCS1-PCSm total output power is 0.

Step 2.2, after the battery stack electric quantity corresponding to the PCS1 is full, the IED controls the PCS1-PCSm to stop charging and discharging; BMS1 calibrates SOH and calibrates SOC 100%.

It is further preferred that step 2 also includes step 2.3, the ied is allowed to stand for a set period of time, preferably but not limited to 30 minutes, after the ied has controlled the PCS1-PCSm to stop charging and discharging.

And 3, discharging the calibrated battery stack calibrated in the step 2 at rated power, charging the rest battery stacks in an SOC calibration interval, wherein the total output power is 0, discharging the calibrated battery stack until the set SOC stops all charging and discharging, and recording SOC, voltage and temperature data of the calibrated battery stack in the discharging process.

In a preferred but non-limiting embodiment of the invention, calibrating the stack discharge to 10% SOC stops full charge-discharge.

In a preferred but non-limiting embodiment of the present invention, step 3 comprises:

step 3.1, continuously selecting PCS1 as a calibration battery stack for example, controlling PCS1 to discharge at rated power by the IED, charging PCS2-PCSm, controlling the total output power of PCS1-PCSm to be 0, and recording SOC, voltage and temperature data of the calibration battery stack in the discharging process of the calibration battery stack;

and 3.2, after the PCS1 corresponding battery stack is discharged to the SOC of 10%, the IED controls the PCS1-PCSm to stop charging and discharging.

It is further preferred that step 3 also includes step 3.3, the ied is allowed to stand for a set period of time, preferably but not limited to 30 minutes, after the ied has controlled the PCS1-PCSm to stop charging and discharging.

And 4, charging the calibrated battery stack calibrated in the step 3 with rated power, discharging the rest battery stacks, wherein the total output power is 0, charging the calibrated battery stack to a set SOC, stopping all charging and discharging, and recording SOC, voltage and temperature data in the charging process of the calibrated battery stack.

In a preferred but non-limiting embodiment of the invention, calibrating the stack charge to 90% SOC stops full charge and discharge.

In a preferred but non-limiting embodiment of the present invention, step 4 comprises:

in step 4.1, the IED controls PCS1 to charge at rated power, PCS2-PCSm to discharge, and controls PCS1-PCSm total output power to be 0.

And 4.2, after the PCS1 corresponding battery stack is charged to the SOC of 90%, the IED controls the PCS1-PCSm to stop charging and discharging.

It is further preferred that step 4 also includes step 4.3, where the IED controls the PCS1-PCSm to stop charging and discharging, and then to stand for a set period of time, preferably but not limited to 30 minutes.

And 5, sending the data related to the SOC, the voltage and the temperature recorded in the process of calibrating the battery stack in the step 3 and the step 4 to the EMS.

Step 6, repeating the steps 1 to 5 for the rest of the battery stacks in the SOC calibration interval until all the battery stacks in the SOC calibration interval are calibrated; the energy management system gathers and calculates the data to obtain an OCV correction curve and sends the OCV correction curve to the battery module management unit.

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

In a preferred but non-limiting embodiment of the invention, the EMS aggregates the offline calibration SOC, voltage and temperature data, derives an optimal OCV correction curve based on a Kalman filter algorithm, and issues an online SOC calibration algorithm to the BMU update BMS.

Notably, the core concept of the present invention includes at least: the invention is calibrated in a hot standby state based on big data, the operation of the whole station is not affected, if necessary, the PMS can stop the calibration of the SOC at any time, and the control of the PCS1-PCSm is recovered.

As shown in fig. 2, embodiment 2 of the present invention provides a control system used in a method for automatic SOC calibration in hot standby of energy storage of a large lithium battery. Wherein, the number 2 represents an energy storage system monitoring data network, which is used for data interaction between IED, PMS, BMS, PCS equipment and EMS, and can adopt IEC 61850 or IEC 104 protocol; the number 4 represents an energy storage system control data network, which is used for rapid interaction of control data among IED, PMS, PCS devices and can adopt GOOSE protocol; the IED is installed on the site of the energy storage equipment, acquires the voltage and the current of grid connection points of all PCSs controlled by the IED, and calculates and controls the real-time output power of a plurality of PCSs.

The meaning of the terms and the reference numerals are as follows:

1: the energy management system of the energy storage power station is used for monitoring the energy storage power station;

2: the energy storage power station monitoring data network is used for monitoring data interaction between EMS, IED, PMS, BMS, PCS;

3: a PMS, an energy storage power station total station coordination controller, a power supply system and a power supply system, wherein the PMS is used for controlling an energy storage total station PCS;

4: the energy storage power station control data network is used for quickly interacting power control data among IED, PMS, PCS;

5: a BMS, a battery management system for monitoring and protecting the battery system;

6: PCS, energy storage converter, which is used for AC/DC conversion;

7: BMS and PCS data interaction network, is used for BMS and PCS data interaction;

8: BCMU, battery cluster level management unit for monitoring and protecting battery clusters;

9: the BMU is used for monitoring and protecting the battery module;

10: and the IED is used for controlling the charging and discharging of the PCSs.

The present disclosure may be a system, method, and/or computer program product. The computer program product may include a computer readable storage medium having computer readable program instructions embodied thereon for causing a processor to implement aspects of the present disclosure.

Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that: modifications and equivalents may be made to the specific embodiments of the invention without departing from the spirit and scope of the invention, which is intended to be covered by the claims.

Claims (10)

1. The automatic SOC calibration method under the standby of the energy storage heat of the large lithium battery is characterized by comprising the following steps of:

step 1, selecting a calibrated cell stack in an SOC calibration interval, discharging the calibrated cell stack with rated power, charging other cell stacks in the SOC calibration interval, wherein the total output power of the SOC calibration interval is 0, stopping all charging and discharging after the electric quantity of the calibrated cell stack is emptied, and setting the SOC value of the calibrated cell stack to 0%;

step 2, charging the cell stack calibrated in the step 1 with rated power, discharging the rest cell stacks in an SOC calibration interval, stopping all charging and discharging until the electric quantity of the calibrated cell stack is full, calibrating the SOC value of the cell stack to be 100%, and calibrating SOH;

step 3, discharging the calibrated battery stack calibrated in the step 2 at rated power, charging other battery stacks in an SOC calibration interval, wherein the total output power is 0, discharging the calibrated battery stack until the set SOC stops all charging and discharging, and recording SOC, voltage and temperature data of the calibrated battery stack in the discharging process;

step 4, charging the calibrated battery stack calibrated in the step 3 with rated power, discharging the rest battery stacks, wherein the total output power is 0, charging the calibrated battery stack to a set SOC, stopping all charging and discharging, and recording SOC, voltage and temperature data of the calibrated battery stack in the charging process;

step 5, sending the SOC, voltage and temperature related data recorded in the process of the calibrated battery stack calibrated in the step 3 and the step 4 to an EMS;

step 6, repeating the steps 1 to 5 for the rest of the battery stacks in the SOC calibration interval until all the battery stacks in the SOC calibration interval are calibrated; the energy management system gathers and calculates the data to obtain an OCV correction curve and sends the OCV correction curve to the battery module management unit.

2. The method for automatic SOC calibration under hot standby of large lithium battery energy storage of claim 1, wherein the method comprises the steps of:

the step 1 comprises the following steps:

step 1.1, after starting SOC calibration, EMS sends an SOC calibration interval to PMS and IED, a coordination controller stops controlling an energy storage converter, a charge-discharge control device selects PCSi as a calibration cell stack, and i is a natural number not greater than m;

step 1.2, the PMS stops controlling the PCS1-PCSm, and m represents the number of PCS in the SOC calibration interval;

in step 1.3, the IED controls PCSi to discharge at rated power, PCS other than PCSi to charge, and controls PCS1-PCSm total output power to 0.

3. The method for automatic SOC calibration under hot standby of large lithium battery energy storage of claim 2, wherein the method comprises the steps of:

the step 2 comprises the following steps:

step 2.1, the IED controls PCSi to charge at rated power, the rest PCS discharges, and the total output power of PCS1-PCSm is 0;

step 2.2, after the PCSi is fully charged corresponding to the battery stack electric quantity, the IED controls the PCS1-PCSm to stop charging and discharging; BMS1 calibrates SOH and calibrates SOC 100%.

4. The method for automatic SOC calibration under hot standby for energy storage of a large lithium battery as claimed in claim 3, wherein:

the step 3 comprises the following steps:

step 3.1, the IED controls PCSi to discharge at rated power, the rest PCS charges, controls the total output power of PCS1-PCSm to be 0, and records SOC, voltage and temperature data in the process of calibrating the discharging of the battery stack;

and 3.2, after the PCS1 corresponding battery stack is discharged to the SOC of 10%, the IED controls the PCS1-PCSm to stop charging and discharging.

5. The method for automatic SOC calibration under hot standby for energy storage of a large lithium battery as claimed in claim 4, wherein the method comprises the steps of:

step 4 comprises:

step 4.1, the IED controls PCSi to charge at rated power, the rest PCS discharges, and the total output power of PCS1-PCSm is controlled to be 0;

and 4.2, after the PCS1 corresponding battery stack is charged to the SOC of 90%, the IED controls the PCS1-PCSm to stop charging and discharging.

6. The method for automatic SOC calibration under hot standby for energy storage of a large lithium battery as claimed in claim 4, wherein the method comprises the steps of:

between step 1 and step 2, between step 2 and step 3, between step 3 and step 4, still include setting for long standing.

7. The method for automatic SOC calibration under hot standby for energy storage of a large lithium battery as claimed in claim 4, wherein the method comprises the steps of:

and (3) calibrating in the hot standby state, wherein the coordination controller can terminate SOC calibration at any time and resume the control of the energy storage converter.

8. The method for automatic SOC calibration under hot standby for energy storage of a large lithium battery as claimed in claim 4, wherein the method comprises the steps of:

in step 6, the EMS collects the offline calibration SOC, voltage and temperature data, obtains an optimal OCV correction curve based on a Kalman filter algorithm, and sends the optimal OCV correction curve to an online SOC verification algorithm of the BMU updating BMS.

9. A control system for automatic SOC calibration in a large lithium battery hot standby, performing a method for automatic SOC calibration in a large lithium battery hot standby as claimed in any of claims 1-8, comprising:

the energy storage system monitors a data network for data interaction between IED, PMS, BMS, PCS equipment and the EMS; after starting SOC calibration, the EMS transmits an SOC calibration interval to the PMS and the IED, and the coordination controller stops controlling the energy storage converter;

the energy storage system control data network is used for controlling data interaction among IED, PMS, PCS devices;

the IED is installed on the site of the energy storage equipment, acquires the voltage and current of grid-connected points of all PCSs controlled by the IED, and calculates and controls the real-time output power of a plurality of PCSs; during calibration, the IED controls the calibrated battery stack to charge or discharge at rated power, and the rest battery stacks correspondingly discharge or charge, so that the total output power is 0.

10. The control system for automatic SOC calibration in hot standby for large lithium battery storage of claim 9, wherein:

the energy storage system monitoring data network adopts IEC 61850 or IEC 104 protocol;

the energy storage system controls the data network to adopt GOOSE protocol.