Operation management device, operation management method, and computer program

Abstract

Provision of operation management equipment, operation management methods, and computer programs. [Solution] The system comprises at least one processing unit, which converts a first operational SOC based on the integrated current value of the energy storage elements mounted in the energy storage system to a second operational SOC based on the amount of energy, and outputs the value of the second operational SOC after conversion.

Description

[Technical Field]

[0001] This disclosure relates to an operation management device, an operation management method, and a computer program. [Background technology]

[0002] Energy storage systems that store electricity supplied by power generation facilities such as solar and wind power plants, and then supply that stored electricity to loads such as factories and office buildings as needed, are becoming widespread. These energy storage systems are equipped with multiple banks.

[0003] In energy storage systems, it is necessary to manage the charging and discharging of each bank to ensure a stable power supply. In energy storage systems with multiple banks, the State of Charge (SOC) is calculated by a management device for each bank. At the system level, the highest bank SOC, average SOC, and lowest bank SOC are calculated from the SOC calculated for each bank. Higher-level systems such as a Power Conditioning System (PCS) or Energy Management System (EMS) use one SOC selected from the highest, average, and lowest SOCs as an indicator to perform charging and discharging control for each bank. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2016 / 135853 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Conventional systems display the current state of charge (SOC) of a bank based on the bank's current capacity (Ah). If the total charge / discharge capacity of the entire system is estimated based on the integrated current value, there is a concern that it may not be able to discharge as much as expected, or that the system may shut down with remaining capacity.

[0006] An object of the present disclosure is to provide an operation management device, an operation management method, and a computer program that can convert an operational state of charge (SOC) based on an integrated current value into an operational SOC based on electric energy and output the converted operational SOC. Means for Solving the Problem

[0007] The operation management device of the present disclosure includes at least one processing unit, wherein the processing unit converts a first operational SOC based on an integrated current value of a power storage element mounted in a power storage system into a second operational SOC based on electric energy, and outputs the value of the converted second operational SOC. Effects of the Invention

[0008] According to the present disclosure, an operational SOC based on an integrated current value can be converted into an operational SOC based on electric energy and output. Brief Description of the Drawings

[0009] [Figure 1] FIG. 1 is a schematic diagram showing the overall configuration of a storage capacity management system according to an embodiment. [Figure 2] FIG. 2 is an explanatory diagram illustrating the internal configuration of a storage battery panel and a control panel in a power storage system. [Figure 3] FIG. 3 is a block diagram illustrating the configuration of a host system. [Figure 4] FIG. 4 is an explanatory diagram outlining a method for determining an operational SOC. [Figure 5] FIG. 5 is an explanatory diagram illustrating details of a calculation method for an operational SOC in a high SOC region. [Figure 6] FIG. 6 is an explanatory diagram illustrating details of a calculation method for an operational SOC in a low SOC region. [Figure 7] FIG. 7 is a flowchart showing a procedure for determining an operational SOC. [Figure 8] FIG. 8 is a flowchart showing a procedure for determining an operational SOC. [Figure 9] FIG. 9 is a conceptual diagram of a table showing the relationship between a capacity retention rate and upper-limit SOC and lower-limit SOC. [Figure 10] This is a conceptual diagram of a table showing the relationship between the first operational SOC and the second operational SOC. [Figure 11] This is a flowchart showing the procedure for determining the operational State of Control (SOC) based on electricity consumption. [Figure 12] This is a flowchart showing the procedure for determining the operational State of Control (SOC) based on electricity consumption. [Modes for carrying out the invention]

[0010] (1) The operation management device of the present disclosure comprises at least one processing unit, which converts a first operation SOC based on the integrated current value of the energy storage elements mounted on the energy storage system to a second operation SOC based on the amount of energy, and outputs the value of the second operation SOC after conversion.

[0011] An energy storage system is installed alongside power generation facilities such as solar power generation facilities and wind power generation facilities. It stores the electricity supplied from the power generation facilities and supplies the stored electricity to the load. An example of an energy storage system is an ESS (Energy Storage System). Alternatively, an energy storage system may be a power conditioner or a backup power supply unit.

[0012] The energy storage system comprises multiple banks connected in parallel. Each bank consists of multiple battery modules connected in series. The energy storage system includes a management unit (bank BMU) for each bank to monitor or control the multiple banks. The energy storage system further includes a higher-level management unit (domain BMU) to monitor or control the multiple banks.

[0013] Each bank BMU acquires measurement data, such as current, measured for the corresponding bank, and calculates the State of Charge (SOC) for that bank based on the acquired measurement data. The current integration method is often used to calculate the SOC.

[0014] When using a State of Charge (SOC) based on the integrated current value, the amount of energy that can be extracted when the SOC discharges from 100% to 50% is different from the amount of energy that can be extracted when the SOC discharges from 50% to 0%. Conventional systems display the current charge status of a bank based on the integrated current value (Ah) of the bank, making it difficult for the average user to understand the amount of energy that can be extracted from the energy storage system.

[0015] According to the operation management device described in (1) above, the first operational SOC, which is based on the integrated current value, is converted to a second operational SOC, which is based on the amount of energy, and output. By checking the second operational SOC output from the operation management device, the user can easily understand the amount of energy that can be extracted from the energy storage system.

[0016] (2) The operation management device described in (1) above includes a storage unit that stores a table or function showing the relationship between the first operation SOC and the second operation SOC, and the processing unit may convert the first operation SOC to the second operation SOC by referring to the table or function stored in the storage unit.

[0017] According to the operation management device described in (2) above, a first operation SOC based on the integrated current value can be converted to a second operation SOC based on the energy quantity using a table or function.

[0018] (3) In the operation management device described in (1) or (2) above, the processing unit may acquire individual SOCs based on the integrated current values ​​of a plurality of energy storage elements mounted on the energy storage system, aggregate the acquired individual SOCs to calculate a plurality of aggregated SOCs, and determine the first operation SOC to be used in the energy storage system based on the calculated plurality of aggregated SOCs.

[0019] In energy storage systems with multiple banks, a State of Charge (SOC) is calculated for each bank. Generally, there are individual differences between banks, and the degree of degradation also differs from bank to bank, so the calculated individual SOCs will vary between banks. Therefore, if the charging and discharging capacity of the energy storage system is estimated and controlled based on any one of the individual SOCs, or the average value (highest or lowest value) of the individual SOCs, there is a concern that the system may not be able to discharge as much as expected, or that the system may be shut down with excess capacity remaining.

[0020] According to the operation management device described in (3) above, the individual SOC for each bank is aggregated to calculate the aggregated SOC, and the operational SOC to be used for the energy storage system is determined based on the calculated aggregated SOC. For example, the operational SOC can be set within the range of the upper limit of the energy storage system that can be charged and the lower limit of the energy storage system that can be discharged. Therefore, by using the operational SOC as an indicator, it is possible to avoid situations where the system cannot be discharged as much as expected, or where the system is shut down with excess capacity remaining.

[0021] (4) In the operation management device described in (3) above, the processing unit may calculate the minimum SOC, the maximum SOC, and the average SOC from among the individual SOCs of the plurality of energy storage elements as the aggregated SOC, and in the high SOC region where the SOC is higher than the first set value, the first operation SOC may be determined so as charging progresses that it approaches the maximum SOC from the average SOC.

[0022] According to the operation management device described in (4) above, in the high SOC region, as charging progresses, the operational SOC of the entire energy storage system is determined so that it approaches the maximum SOC from the average SOC calculated from the individual SOCs.

[0023] (5) In the operation management device described in (3) above, the processing unit may calculate the minimum SOC, the maximum SOC, and the average SOC from among the individual SOCs of the plurality of energy storage elements as the aggregated SOC, and in the low SOC region where the SOC is lower than the second set value, the first operation SOC may be determined so as discharge progresses that the average SOC approaches the minimum SOC.

[0024] According to the operation management device described in (5) above, in the low SOC region, as discharge progresses, the operating SOC of the entire energy storage system is determined so that it approaches the minimum SOC from the average SOC calculated from the individual SOCs.

[0025] (6) In the operation management device described in (3) above, the processing unit may calculate the minimum SOC, the maximum SOC, and the average SOC from among the individual SOCs of the plurality of energy storage elements as the aggregated SOC, and determine the operation SOC to be equal to the average SOC in the intermediate SOC region where the SOC is lower than the first set value and higher than the second set value.

[0026] According to the operation management device described in (6) above, in the intermediate SOC region, the average SOC obtained from individual SOCs is defined as the operation SOC for the entire energy storage system.

[0027] (7) In the operation management device described in any one of (1) to (6) above, the energy storage system may be a system for storing electricity that is bought and sold in the electricity market.

[0028] According to the operation management device described in (7) above, the amount of electricity that can be extracted from the energy storage system can be easily estimated.

[0029] (8) The operational management method of this disclosure involves a computer performing a process to convert a first operational SOC, which is based on the integrated current value of the energy storage elements installed in the energy storage system, into a second operational SOC, which is based on the amount of energy, and outputting the value of the second operational SOC after the conversion.

[0030] According to the operation management method described in (8) above, the user can easily determine the amount of electricity that can be extracted from the energy storage system by checking the second operation SOC output from the operation management device.

[0031] (9) The computer program of this disclosure is a computer program that causes a computer to perform a process of converting a first operational SOC, which is based on the integrated current value of the energy storage elements installed in the energy storage system, into a second operational SOC, which is based on the amount of energy, and outputting the value of the second operational SOC after the conversion.

[0032] According to the computer program described in (9) above, the user can easily determine the amount of electricity available for extraction from the energy storage system by checking the second operational SOC output from the operation management device.

[0033] The present invention will be described in detail below with reference to the drawings illustrating its embodiments. (Embodiment 1) Figure 1 is a schematic diagram showing the overall configuration of a power storage capacity management system according to an embodiment. The power storage capacity management system according to the embodiment comprises a power storage system 1, a higher-level system 2, and a user terminal 3. The power storage system 1 is, for example, an ESS, which stores electricity supplied from a power generation facility PG and supplies the stored electricity to a load PC. The power generation facility PG includes solar power generation facilities, wind power generation facilities, etc. The load PC includes power consuming facilities such as factories, office buildings, schools, hospitals, restaurants, and airports.

[0034] The energy storage system 1 may store electricity supplied from the power generation equipment PG and supply the stored electricity to the power grid PS. The energy storage system 1 may also store electricity supplied from the power grid PS and supply the stored electricity to the load PC.

[0035] The energy storage system 1 comprises a battery panel 10 and a control panel 11. The battery panel 10 comprises multiple banks 101. Each bank 101 is configured by electrically connecting multiple battery modules BT in series. In the example in Figure 1, the battery panel 10 comprises three banks 101, and each bank 101 is configured by electrically connecting a total of 18 battery modules BT in two vertical rows in series. These three banks 101 are connected in parallel to each other. A group of banks 101 connected in parallel is also called a domain. The number of banks 101 in the battery panel 10, the number of battery modules BT constituting each bank 101, and the number of domains in the energy storage system 1 are designed as appropriate.

[0036] The battery module BT is constructed by connecting multiple battery cells in series. In one example, the battery cells are lithium-ion secondary batteries. Alternatively, the battery cells may be solid-state batteries, lead-acid batteries, redox flow batteries, zinc-air batteries, alkaline manganese batteries, lithium-sulfur batteries, sodium-sulfur batteries, silver-zinc oxide batteries, nickel-metal hydride batteries, molten salt thermal batteries, etc., or they may be capacitors. The number of battery cells constituting the battery module BT is designed as appropriate.

[0037] The control panel 11 is a control device that manages the status of banks 101 installed in the battery storage panel 10 and controls the charging and discharging of each bank 101 according to the status of each bank 101. For example, the control panel 11 acquires measurement data such as current, voltage, and temperature measured for each bank 101, and data such as the State of Charge (SOC) calculated for each bank 101 from the battery storage panel 10. The control panel 11 uses the individual SOC acquired from the battery storage panel 10 to determine the operational SOC to be used for the battery storage system. The operational SOC is a unique value used for the system. Based on the various data acquired from the battery storage panel 10 and the determined operational SOC, the control panel 11 controls the charging and discharging of each bank 101.

[0038] The energy storage system 1 may further include a power converter 12. The power converter 12 converts the power (AC power or DC power) supplied from the power generation equipment PG into DC power of the required magnitude and supplies the converted DC power to the battery storage panel 10. The battery storage panel 10 stores the power supplied from the power generation equipment PG through the power converter 12. The battery storage panel 10 supplies the stored power to the load PC in response to an external request. The power converter 12 converts the power supplied from the battery storage panel 10 to the load PC from DC power to AC power.

[0039] In this embodiment, the energy storage system 1 is configured to include one battery panel 10, one control panel 11, and one power converter 12. Alternatively, the energy storage system 1 may include multiple battery panels 10, or multiple control panels 11 for controlling multiple battery panels 10. The battery panels 10 and control panels 11 may be housed in a container. The energy storage system 1 may further include ancillary equipment such as an air conditioner and lighting equipment.

[0040] The higher-level system 2 is, for example, an EMS connected to the energy storage system 1 via a communication network NW. The higher-level system 2 acquires data from the energy storage system 1, such as time-series data of current, voltage, and temperature for each bank 101, individual SOC for each bank 101, and the overall system operation SOC. The higher-level system 2 stores the data acquired from the energy storage system 1 in a database as a usage history database, or displays it on a monitor as data representing the status of the energy storage system 1. The higher-level system 2 manages the amount of power that the power generation equipment PG can supply, the amount of power demand required by the load PC, etc., and instructs the energy storage system 1 to charge and discharge based on the power supply and demand relationship between the power generation equipment PG and the load PC.

[0041] User terminal 3 is a user terminal that is connected to the higher-level system 2 via a communication network NW, enabling access to it. By accessing the higher-level system 2, user terminal 3 obtains information about the energy storage system 1 (individual SOC, operational SOC) and displays the obtained information about the energy storage system 1 on its screen.

[0042] Figure 2 is an explanatory diagram illustrating the internal configuration of the battery panel 10 and control panel 11 in the energy storage system 1. The battery panel 10 of the energy storage system 1 comprises multiple banks 101 and a Bank BMU (Battery Management Unit) 102 provided corresponding to each bank 101. In the example in Figure 2, the battery panel 10 comprises three banks 101 and three Bank BMUs 102 provided corresponding to each bank 101. The three banks 101 of the battery panel 10 constitute a domain 110.

[0043] Bank 101 is connected to the outside (power converter 12, power source, power supply destination, etc.) via the main circuit MC. The main circuit MC has a main path P1 that is connected to the outside and branch paths P2 that branch off from the main path P1 and are connected to each bank 101. A switch for switching the target of charging and discharging may be provided in the branch path P2.

[0044] The power source for bank 101 is the power generation equipment PG (or power grid PS), and the power destination of bank 101 is the load PC (or power grid PS). A power converter 12 may be provided between bank 101 and the power source or power destination. Bank 101 stores (charges) the power supplied through the power converter 12 and the main circuit MC, and supplies (discharges) the stored power to an external power destination through the main circuit MC and the power converter 12.

[0045] Each bank 101 is equipped with a current sensor SA, a voltage sensor SV, and a temperature sensor ST. The current sensor SA is an existing current sensor such as a Hall sensor, and measures the current flowing through each bank 101 in a time series. The voltage sensor SV is an existing voltmeter, and measures the voltage of each bank 101 in a time series. The temperature sensor ST is an existing temperature sensor such as a thermistor, and is installed inside or near each bank 101 to measure the temperature of each bank 101 in a time series. Multiple sensors may be provided. For example, a voltage sensor SV may be provided for each battery module BT. The temperature sensor ST may be provided at multiple locations in bank 101 to measure the temperature at multiple locations. The current sensor SA, voltage sensor SV, and temperature sensor ST output signals indicating the measurement results to bank BMU 102.

[0046] Bank BMU102 is a management device for managing the status of the corresponding bank 101. Bank BMU102 acquires time-series data of electrical values ​​(current and voltage) or temperature, which are sensor outputs from the current sensor SA, voltage sensor SV, and temperature sensor ST. Based on the acquired time-series data of electrical values ​​or temperature, Bank BMU102 manages the status of bank 101. For example, Bank BMU102 manages the status of bank 101 at each time by calculating the State of Charge (SOC) of bank 101 based on the acquired time-series data of electrical values ​​or temperature. Existing methods such as the current integration method are used for calculating the SOC. Bank BMU102 notifies the higher-level domain BMU111 of the acquired time-series data of current, voltage, temperature, etc., and the calculated SOC data of bank 101. Bank BMU102 may control the start and stop of charging and discharging according to the status of the bank 101 it manages.

[0047] The control panel 11 of the energy storage system 1 includes a domain BMU 111, a memory 112, and a communication interface (communication IF) 113. The domain BMU 111 is a management device for managing the status of domain 110 (the entire bank).

[0048] Domain BMU111 is connected to the bank BMU102 of each bank 101 in a communicative manner. Existing communication standards such as CAN (Controller Area Network) are used for communication between Domain BMU111 and each bank BMU102. Alternatively, communication standards such as LIN (Local Interconnect Network), ECHONET®, and ECHONETLight® may be used. Domain BMU111 acquires time-series data of electrical values ​​and temperature for bank 101, as well as individual SOC data for each bank 101 calculated by each bank BMU102, from each bank BMU102.

[0049] Domain BMU111 is a processing circuit or arithmetic circuit equipped with a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc. The CPU of Domain BMU111 controls various hardware parts by reading and executing various computer programs stored in ROM or memory 112, thereby making the entire device function as an operation management device in this disclosure.

[0050] Alternatively, the domain BMU111 may be any arithmetic circuit equipped with multiple CPUs, multi-core CPUs, GPUs (Graphics Processing Units), microcontrollers, volatile or non-volatile memory, etc. The domain BMU111 may also be equipped with functions such as a timer for measuring the elapsed time from the time a measurement start instruction is given until a measurement end instruction is given, a counter for counting numbers, and a clock for outputting date and time information.

[0051] Memory 112 is equipped with a storage device such as flash memory. Various computer programs and data are stored in Memory 112. The computer programs (program products) stored in Memory 112 include the operational SOC determination program DP for determining the operational SOC used in the energy storage system. The data stored in Memory 112 includes various data used in the operational SOC determination program DP and data generated by the domain BMU 111.

[0052] The computer program, including the operational SOC determination program DP, is provided on a non-temporary recording medium RM on which the computer program is recorded in a readable format. The recording medium RM is a portable memory such as a CD-ROM, USB memory, or SD (Secure Digital) card. The domain BMU 111 reads the desired computer program from the recording medium RM using a reader device (not shown in the diagram) and stores the read computer program in memory 112. Alternatively, the computer program, including the operational SOC determination program DP, may be provided via communication.

[0053] The operational SOC determination program DP may be a single computer program or a group of programs composed of multiple computer programs. The operational SOC determination program DP may partially utilize existing libraries. Furthermore, the operational SOC determination program DP may be executed on a single computer or executed collaboratively by multiple computers.

[0054] Domain BMU111 calculates the operational SOC to be used for energy storage system 1 by executing the operational SOC determination program DP, using the individual SOC for each bank 101 obtained from each bank BMU102. The calculation method will be described in detail later.

[0055] The communication interface 113 is equipped with an interface for connecting to an external communication network NW. The communication interface 113 is a wireless communication interface such as WiFi (registered trademark), 3G, 4G, 5G, or LTE (Long Term Evolution), or a wired communication interface such as Ethernet (registered trademark). The domain BMU 111 transmits data such as time-series data of electrical values ​​and temperature of bank 101 obtained from each bank BMU 102, individual SOCs for each bank, and the overall system operation SOC to the higher-level system 2 via the communication interface 113.

[0056] Figure 3 is a block diagram illustrating the configuration of the higher-level system 2. The higher-level system 2 is a dedicated or general-purpose computer system and includes a control unit 21, a storage unit 22, a communication unit 23, an operation unit 24, a display unit 25, and the like.

[0057] The control unit 21 is a processing circuit or arithmetic circuit equipped with a CPU, ROM, RAM, etc. The CPU of the control unit 21 controls the various hardware parts by reading and executing various computer programs stored in the ROM or storage unit 22, thereby making the entire device function as a higher-level system in this disclosure.

[0058] Alternatively, the control unit 21 may be any arithmetic circuit equipped with multiple CPUs, a multi-core CPU, a GPU (Graphics Processing Unit), a microcontroller, volatile or non-volatile memory, etc. The control unit 21 may also include functions such as a timer for measuring the elapsed time from the time a measurement start instruction is given until a measurement end instruction is given, a counter for counting numbers, and a clock for outputting date and time information.

[0059] The storage unit 22 includes a storage device such as a hard disk or flash memory. Various computer programs and data are stored in the storage unit 22. The computer programs are provided on a non-temporary recording medium on which the computer programs are recorded in a readable format. The recording medium is a portable memory such as a CD-ROM, USB memory, or SD card. The control unit 21 reads the desired computer program from the recording medium using a reading device (not shown in the figure) and stores the read computer program in the storage unit 22. Alternatively, the computer programs to be stored in the storage unit 22 may be provided via communication.

[0060] The communication unit 23 is equipped with a communication interface that connects to a communication network NW. The communication interface provided by the communication unit 23 is a wireless communication interface such as WiFi (registered trademark), 3G, 4G, 5G, or LTE (Long Term Evolution), or a wired communication interface such as Ethernet (registered trademark). The communication unit 23 transmits and receives various types of data through the communication network NW.

[0061] The operation unit 24 is equipped with input devices such as a keyboard and mouse, and accepts operations from administrators, etc. The display unit 25 is equipped with a display device such as a liquid crystal display, and displays information that should be notified to administrators, etc. Alternatively, the higher-level system 2 may be configured to accept necessary operations via an external computer and transmit information that should be notified to administrators, etc. to the external computer. In this case, the higher-level system 2 does not need to be equipped with the operation unit 24 and the display unit 25.

[0062] In this embodiment, the higher-level system 2 may be a computer system composed of multiple computers and peripheral devices, or it may be a single computer. Alternatively, the higher-level system 2 may be a virtual machine whose actual entity is virtualized, or it may be a cloud.

[0063] The following explains the methodology for determining the operational SOC. Figure 4 is an explanatory diagram illustrating the general method for determining the operational SOC. The bank BMU 102 mounted on the battery panel 10 acquires time-series data obtained by measuring the current, voltage, temperature, etc., of the corresponding bank 101. Based on the acquired time-series data, the bank BMU 102 calculates the SOC (individual SOC) of each bank 101. In this embodiment, the bank BMU 102 calculates the individual SOC using the current integration method. The bank BMU 102 calculates the SOC by integrating the current values ​​measured by the current sensor SA to determine the amount of charge entering and leaving bank 101, and then dividing by the total charge amount (full charge capacity) of bank 101.

[0064] Alternatively, Bank BMU102 may calculate the SOC using a voltage method that uses the relationship between terminal voltage or OCV (Open Circuit Voltage) and SOC, or a model-based calculation method that uses a model such as an equivalent circuit model or a Kalman filter. Bank BMU102 notifies Domain BMU111 of the individual SOCs it has calculated.

[0065] Domain BMU111 acquires individual SOCs notified from each bank BMU102. If the number of banks 101 installed in the battery panel 10 is n, the individual SOCs are BMU-SOC bank1 BMU-SOC bank2 ,…,BMU-SOC bankn It is written as follows.

[0066] Domain BMU111 aggregates the individual SOCs acquired from each bank 101 to calculate the aggregated SOC. Specifically, Domain BMU111 calculates the highest value of the individual SOCs, which is the maximum SOC (= BMU-SOC). max ), the average SOC (=BMU-SOC) ave ), and the lowest value, the minimum SOC (=BMU-SOC) min Calculate ).

[0067] The domain BMU 111 may calculate a converted SOC converted based on the upper limit SOC and lower limit SOC in the power storage system 1. The upper and lower limits of the individual SOC that can be used for the power storage system 1 are set for the upper limit SOC and lower limit SOC. Here, the upper limit of the individual SOC represents the SOC in a state where the power is limited by the power limiting function of the power storage system 1, or a state where charging is stopped due to a rise in cell voltage. The lower limit of the individual SOC represents the SOC in a state near the discharge lower limit of the power storage system 1, or a state where discharging is stopped due to a decrease in cell voltage. Let the upper limit SOC be SOC up , let the lower limit SOC be SOC low , and when the SOC before conversion is denoted as BMU-SOC, the converted SOC is calculated by the following Equation 1.

[0068] [Expression]

[0069] According to Equation 1, when the individual SOC matches the lower limit SOC, the converted SOC is 0%, and when the individual SOC matches the upper limit SOC, the converted SOC is 100%.

[0070] The domain BMU 111 converts each aggregated SOC according to Equation 1, and obtains the maximum SOC which is the maximum value of converted SOCs (=converted SOC max ), the average SOC which is the average value (=converted SOC ave ), and the minimum SOC which is the minimum value (=converted SOC min ).

[0071] The domain BMU 111 determines which of the high SOC region, the intermediate SOC region, and the low SOC region the current power storage system 1 belongs to. For example, the domain BMU 111 determines that the converted SOC max belongs to the high SOC region if the converted SOC is equal to or greater than a first set value (e.g., 90%), and determines that it belongs to the low SOC region if the converted SOC min is equal to or less than a second set value (e.g., 10%). The domain BMU 111 determines that the converted SOC max is less than the first set value, and the converted SOC minIf it exceeds the second setting value, it is determined to belong to the intermediate SOC region.

[0072] Domain BMU111 determines the operational SOC depending on whether the current energy storage system 1 belongs to the high SOC region, the intermediate SOC region, or the low SOC region. For example, if it is determined that the current energy storage system 1 belongs to the high SOC region, Domain BMU111 determines the operational SOC so that it approaches the maximum SOC from the average SOC as charging progresses. If it is determined that the current energy storage system 1 belongs to the low SOC region, Domain BMU111 determines the operational SOC so that it approaches the minimum SOC from the average SOC as discharging progresses. If it is determined that the current energy storage system 1 belongs to the intermediate SOC region, it determines the operational SOC so that it is equal to the average SOC.

[0073] In this embodiment, when the operational SOC is determined using the individual SOC calculated by the current integration method, the resulting operational SOC is an SOC based on the current integration value (first operational SOC). Domain BMU111 may convert the SOC based on the current integration value (first operational SOC) to an SOC based on energy consumption (second operational SOC). In Figure 4, the first operational SOC based on the current integration value is denoted as first operational SOC(Ah), and the second operational SOC based on energy consumption is denoted as second operational SOC(Wh). Domain BMU111 notifies the higher-level system 2 of at least one of the individual SOC and the operational SOC (first operational SOC or second operational SOC).

[0074] Figure 5 is an explanatory diagram illustrating the details of the calculation method for operational SOC in the high SOC region. To avoid the operational SOC not reaching 100% (or 99.9%) due to variations in multiple banks 101, domain BMU 111 uses converted SOC max In regions where the percentage exceeds 90% (high SOC region), the equivalent SOC max As it rises from 90%, the converted SOC ave Converted from SOC maxThe operational SOC is output as a value that approaches linearity. Specifically, in the high SOC region, domain BMU111 outputs the operational SOC calculated according to the following equation 2.

[0075]

number

[0076] As shown in Figure 5, the converted SOC during charging max In the intermediate SOC region until it reaches 90%, the operational SOC is equivalent to the equivalent SOC. ave It is equal to the value, but it enters the high SOC region, and the converted SOC max As it rises from 90%, the operational SOC becomes the equivalent SOC. ave Converted from SOC max Approaching.

[0077] Figure 6 is an explanatory diagram illustrating the details of the calculation method for operational SOC in the low SOC region. In order to avoid the operational SOC not reaching 0% (or 0.1%) due to variations in multiple banks 101, domain BMU 111 uses converted SOC min In the region where it is 10 or less (low SOC region), the converted SOC min As it decreases from 10%, the equivalent SOC ave Converted from SOC min The operational SOC is output as a value that approaches linearity. Specifically, in the low SOC region, domain BMU111 outputs the operational SOC calculated according to the following equation 3.

[0078]

number

[0079] As shown in Figure 6, the converted SOC during discharge min In the intermediate SOC region until it reaches 10%, the operational SOC is equivalent to the equivalent SOC. ave It is equal to the value, but falls into the low SOC region, and the converted SOC min As it decreases from 10%, the operational SOC becomes the equivalent SOC. ave Converted from SOCmin Approaching.

[0080] For the intermediate SOC region between the high SOC region and the low SOC region, domain BMU111 is calculated using the converted SOC calculated by Equation 1. ave We have decided to designate it as the operational SOC.

[0081] Domain BMU111 is equivalent SOC max For the range of 90% to 99.9%, the operational SOC can be calculated using equation 2, and if the upper limit of what can be charged as energy storage system 1 is reached, the operational SOC at that time may be set to 100%.

[0082] Specifically, Domain BMU111 should reset the operational SOC to 100% when it detects a state where power is limited by the power limiting function of the energy storage system 1, or a state where charging is stopped due to an increase in cell voltage. For example, Domain BMU111 should reset the operational SOC to 100% when any of the following four conditions are met. (1) When an increase in cell voltage is detected (2) When, during charging operation and current integration, it is detected that the current of bank 101, which has the highest bank voltage, is 1A or less, and the highest cell voltage is 4.2V or higher for 10 seconds: (3) BMU-SOC after OCV reset max ≥SOC up If detected (4) At the previous timing, the operational SOC was 100% and the current BMU-SOC max ≥SOC up If detected

[0083] Domain BMU111 is equivalent SOC min For the range from 10% to 0.1%, the operational SOC can be calculated using Equation 3, and if it reaches the lower limit of discharge possible as energy storage system 1, the operational SOC at that time may be set to 0%.

[0084] Specifically, Domain BMU111 should reset the operational SOC to 0% when it detects that the energy storage system 1 is near its lower discharge limit or that the discharge should be stopped due to a drop in cell voltage. For example, Domain BMU111 should reset the operational SOC to 0% when any of the following three conditions are met. (1) When a decrease in cell voltage is detected (2) If it is detected that the average cell voltage of domain 110 has remained above 3.2V for 10 seconds. (3) At the previous timing, the operational SOC was 0% and the current BMU-SOC min ≦SOC low If detected

[0085] Figures 7 and 8 are flowcharts showing the procedure for determining the operational SOC. While the energy storage system 1 is operating, the current flowing through each bank 101 is measured in time series by the current sensor SA. Each bank BMU 102 acquires the measured values ​​(time series data) from the current sensor SA and calculates the SOC of the corresponding bank 101 (individual SOC) using the current integration method. Each bank BMU 102 outputs the calculated individual SOC to the domain BMU 111 at an appropriate timing.

[0086] Domain BMU111 reads and executes the operational SOC determination program DP from memory 112, thereby performing the following processes: Domain BMU111 acquires individual SOCs output from each of the multiple bank BMU102 (step S101). The individual SOCs acquired from bank BMU102 are, for example, SOCs based on the integrated current value.

[0087] Domain BMU111 aggregates the acquired individual SOCs to calculate multiple aggregated SOCs (step S102). Specifically, Domain BMU111 calculates the highest SOC, the average SOC, and the lowest SOC among the individual SOCs.

[0088] Domain BMU111 converts the calculated aggregated SOC to a converted SOC (step S103). Domain BMU111 converts the upper limit SOC of the energy storage system 1 which is set in advance. up and lower limit SOC low Using this, the aggregated SOC is converted to the converted SOC using Equation 1, and the converted SOC max , conversion SOC ave , and converted SOC min Obtain it.

[0089] In this flowchart, Domain BMU111 first calculated the aggregated SOC, and then converted the aggregated SOC to calculate the converted SOC. Alternatively, Domain BMU111 may calculate the converted SOC by converting the individual SOCs, and then calculate the aggregated SOC from the calculated converted SOC.

[0090] Domain BMU111 determines whether the current energy storage system 1 belongs to the high SOC region (step S104). Domain BMU111 determines the converted SOC max If the value is equal to or greater than the first set value (e.g., 90%), it is determined to belong to the high SOC region. The first set value is not limited to 90% and can be set as appropriate.

[0091] If the current energy storage system 1 is determined to be in the high SOC region (S104: YES), the domain BMU 111 determines whether or not to reset the operational SOC to 100% (step S105). Specifically, the domain BMU 111 determines to reset the operational SOC to 100% if it detects a state in which power is limited by the power limiting function of the energy storage system 1, or a state in which charging is stopped due to an increase in cell voltage. For example, the domain BMU 111 will (1) detect an increase in cell voltage, (2) detect that during charging operation and current integration the current of bank 101 with the highest bank voltage is 1A or less and the highest cell voltage is 4.2V or higher for 10 seconds, or (3) after OCV reset the BMU-SOC max ≥SOC up If this is detected, and (4) at the previous timing the operational SOC was 100% and the current BMU-SOC max ≥SOC upIf any one of the conditions for detection is met, it will be decided to reset the operational SOC to 100%.

[0092] If it is determined to reset the operational SOC to 100% (S105: YES), the domain BMU111 determines the operational SOC of energy storage system 1 to be 100% at that time (step S106). When the operational SOC is reset to 100%, the cell voltage is close to its upper limit (around 4.209V), and the charging current is sufficiently reduced to around 1A. If charging continues after resetting the operational SOC to 100%, the current value may fluctuate slightly around 1A, or the operational SOC may repeatedly fluctuate between 100% and 99.9% in short cycles due to the release of the charging state. Also, if charging is stopped, the current value may exceed 1A, causing the system to move to the calculation step for the high SOC region, and the operational SOC may return to 99.9%. To avoid the above, Domain BMU111 resets the operational SOC to 100% and then maintains the operational SOC at 100% while the maximum SOC is above the upper limit SOC.

[0093] If it is determined that the operational SOC should not be reset to 100% (S105:NO), the domain BMU111 will, as charging progresses, calculate the average SOC (converted SOC). ave ) to the highest SOC (equivalent SOC) max The operational SOC is determined to approach (step S107). Specifically, Domain BMU111 calculates the operational SOC in the high SOC region according to Equation 2.

[0094] In step S104, if it is determined that the current energy storage system 1 does not belong to the high SOC region (S104: NO), then domain BMU 111 determines whether the current energy storage system 1 belongs to the low SOC region (step S108). Domain BMU 111 determines the converted SOC min If the second setting value (e.g., 10%) is below this value, it is determined to belong to the low SOC region. The second setting value is not limited to 10% and can be set as appropriate.

[0095] If the domain BMU 111 determines that the current energy storage system 1 is in the low SOC region (S108: YES), it determines whether or not to reset the operational SOC to 0% (step S109). Specifically, the domain BMU 111 determines to reset the operational SOC to 0% if it detects that the energy storage system 1 is near the lower discharge limit, or that the discharge will stop due to a decrease in cell voltage. For example, the domain BMU 111 should reset the operational SOC to 0% if any of the following three conditions are met: For example, the domain BMU 111 may reset the operational SOC to 0% if (1) a decrease in cell voltage is detected, (2) the average cell voltage of domain 110 has remained above 3.2V for 10 seconds, and (3) the operational SOC was 0% at the previous timing and the current BMU-SOC min ≦SOC low If any one of the conditions for detection is met, it is decided to reset the operational SOC to 0%.

[0096] If it is determined to reset the operating SOC to 0% (S109: YES), the domain BMU111 determines the operating SOC of energy storage system 1 to 0% at that time (step S110). If discharge is stopped when the operating SOC is 0%, the cell voltage will rise. When the average cell voltage exceeds 3.2V, the operating SOC will rise from 0% to 0.1%. That is, since the OCV at 0% operating SOC is about 3.4V, in most cases the reset to 0% operating SOC will only work for a moment and then immediately return to 0.1%. To avoid the above, the domain BMU111 maintains the operating SOC at 0% as long as the minimum SOC is below the lower limit SOC.

[0097] If it is decided not to reset the operational SOC to 0% (S109:NO), the domain BMU111 will, as discharge progresses, reduce the average SOC (converted SOC) ave ) Minimum SOC (equivalent SOC) min The operational SOC is determined to approach (step S111). Specifically, Domain BMU111 calculates the operational SOC in the low SOC region according to Equation 3.

[0098] In step S108, if it is determined that the current energy storage system 1 does not belong to the low SOC region (S108:NO), that is, if it is determined that it belongs to an intermediate SOC that does not belong to either the high SOC region or the low SOC region, the domain BMU111 will determine the converted SOC at that time. ave The system is designated as the operational SOC (Step S112).

[0099] Domain BMU111 notifies the higher-level system 2 of the determined operational SOC via the communication interface (step S113). Alternatively, Domain BMU111 may notify the higher-level system 2 of the individual SOCs of each bank 101 and the operational SOC of the energy storage system 1, or it may notify the higher-level system 2 of either the individual SOC or the operational SOC selected by the user. The notification destination may also be the user terminal 3.

[0100] As described above, in Embodiment 1, the State of Charge (SOC) calculated from the actual battery capacity used in the energy storage system 1 can be presented as the operational SOC, thus avoiding unintended system shutdowns and other issues for the user, and enabling more effective use of battery information.

[0101] (Embodiment 2) Embodiment 2 describes a configuration in which the upper and lower limits of SOC used when calculating the converted SOC are changed according to the capacity retention rate of bank 101. Since the internal configuration of the energy storage system 1 is the same as in Embodiment 1, its explanation will be omitted.

[0102] The bank BMU 102 according to Embodiment 2 measures the capacity retention rate of the corresponding bank 101 at periodic intervals. Existing measurement methods are used for measuring the capacity retention rate. For example, the bank BMU 102 measures the discharge capacity (or charge capacity) of bank 101 by performing constant current discharge (or constant current charge) at a predetermined discharge rate (or charge rate) every N cycles. The bank BMU 102 determines the capacity retention rate by calculating the ratio of the measured discharge capacity (or discharge capacity) to the initial value. Each bank BMU 102 notifies the domain BMU 111 of the measured capacity retention rate of bank 101.

[0103] Domain BMU 111 determines the upper and lower limits of the converted SOC to be used when calculating the SOC, based on the capacity retention rate of each bank 101 notified by bank BMU 102 (e.g., the average capacity retention rate). The relationship between the capacity retention rate of bank 101 and the upper and lower limits of the SOC is stored as a table in memory 112.

[0104] Figure 9 is a conceptual diagram of a table showing the relationship between capacity retention rate and upper and lower SOC limits. Domain BMU111 reads the upper and lower SOC values ​​from the table based on the capacity retention rate obtained from bank BMU102. Domain BMU111 can use the read upper and lower SOC values ​​to convert individual SOCs to equivalent SOCs.

[0105] The values ​​in the table may be updated manually or remotely as needed. The upper and lower SOC values ​​may be given as a function of the capacity retention rate.

[0106] In Embodiment 2, the converted SOC can be corrected by changing the upper and lower limits of SOC according to the cycle degradation of bank 101, so that an appropriate operating SOC can be output according to the degree of degradation of the energy storage system 1.

[0107] (Embodiment 3) Embodiment 3 describes a configuration that converts from an operational SOC based on the current integration value (first operational SOC) to an operational SOC based on the energy consumption (second operational SOC). Since the internal configuration of the energy storage system 1 is the same as in Embodiment 1, its explanation will be omitted.

[0108] The domain BMU111 according to Embodiment 3 converts the first operational SOC to the second operational SOC using a table that shows the relationship between the current integration value-based operational SOC (first operational SOC) and the energy consumption-based operational SOC (second operational SOC).

[0109] Figure 10 is a conceptual diagram of a table showing the relationship between the first operational SOC and the second operational SOC. Domain BMU111 can calculate the current-integrated operational SOC (first operational SOC), and then calculate the energy-based operational SOC (second operational SOC) by referring to the table defined as shown in Figure 10.

[0110] The values ​​in the table may be updated manually or remotely as needed. The power-based operational SOC value may be given as a function of the current-integrated operational SOC value.

[0111] Figures 11 and 12 are flowcharts illustrating the procedure for determining the power-based operational SOC. While the energy storage system 1 is operating, the domain BMU 111 calculates the current-integrated operational SOC using the same procedure as in Embodiment 1 (steps S301 to S312). That is, the domain BMU 111 determines whether the operational SOC is in a state to be reset to 0% or 100%, and whether the energy storage system 1 belongs to the high SOC region, the intermediate SOC region, or the low SOC region. Based on the determination result, the operational SOC is determined from the individual SOCs of bank 101. If the individual SOCs of each bank 101 calculated in bank BMU 102 are current-integrated SOCs, then the current-integrated operational SOC is obtained in steps S306 to S307 and S310 to S312.

[0112] Domain BMU111 converts the determined current-integrated value-based operational SOC to an energy-based operational SOC (step S313). Domain BMU111 can convert the current-integrated value-based operational SOC to an energy-based operational SOC by referring to a table like the one shown in Figure 10. In the table in Figure 10, the range from 0 to 100% is represented by 11 points at 10% intervals, so the energy-based operational SOC can be calculated for the values ​​in between using linear interpolation or the like.

[0113] Domain BMU111 notifies the higher-level system 2 of the converted energy-based operational SOC via the communication interface (step S314). Alternatively, Domain BMU111 may notify the higher-level system 2 of both the current-integrated value-based operational SOC and the energy-based operational SOC, or it may notify the higher-level system 2 of the individual SOCs of each bank 101 together. Domain BMU111 may notify the higher-level system 2 of any one of the individual SOCs selected by the user, the current-integrated value-based operational SOC, or the energy-based operational SOC. The notification destination may be the user terminal 3.

[0114] In Embodiment 3, the operational SOC based on power consumption can be notified to the higher-level system 2 or user terminal 3, so that the actual usable energy storage capacity of the energy storage system 1 can be informed to the administrator or user.

[0115] Conventional systems display the current charge status of a bank based on the bank's current (Ah). Conventional SOC (State of Charge based on integrated current) is calculated by dividing the integrated current measured during charging and discharging by the bank's discharge capacity, which is calculated in advance through capacity measurement tests. The discharge capacity calculated through capacity measurement tests is not uniquely determined because it changes with ambient temperature and age, making it impossible to calculate accurately. Therefore, it is not possible to calculate the SOC accurately when using the integrated current as the basis. Furthermore, conventional SOC is based on the integrated current, not on the amount of energy. In addition, the relationship between SOC and protection values ​​may cause the system to stop charging and discharging. For example, if the amount of energy extracted during discharge from SOC 100% to 50% was 53kWh, it often leads to the misconception that 53kWh of energy can be extracted during discharge from SOC 50% to 0%, even though the amount of energy that can be extracted is actually less than 53kWh (e.g., 47kWh). In this embodiment, since the operational SOC based on energy consumption is output, the actual usable energy storage capacity (charge state) of the energy storage system 1 can be presented to the user.

[0116] The disclosed embodiments are illustrative in all respects and not restrictive. The scope of the invention is defined by the claims and includes all modifications in the sense and scope equivalent to the claims. [Explanation of Symbols]

[0117] 1. Energy storage system 2. Higher-level system 3. User terminals 10 Battery Panel 11 Control Panel 12 Power Converters 101 Bank 102 Bank BMU 111 Domain BMU 112 memory 113 Communication Interface BT Battery Module DP Operation SOC Decision Program

Claims

1. at least one processing unit Equipped with, The aforementioned processing unit, The first operational SOC, which is based on the integrated current value of the energy storage elements installed in the energy storage system, is converted to a second operational SOC, which is based on the amount of energy. Output the value of the second operational SOC after conversion. Operation management device.

2. The system includes a storage unit that stores a table or function indicating the relationship between the first operational SOC and the second operational SOC, The processing unit refers to the table or function stored in the storage unit and converts the first operational SOC to the second operational SOC. The operation management device according to claim 1.

3. The aforementioned processing unit, Individual State of Control (SOC) is acquired based on the integrated current value of multiple energy storage elements installed in the aforementioned energy storage system. The acquired individual SOCs are aggregated to calculate multiple aggregated SOCs. Based on the multiple aggregated SOCs calculated, the first operational SOC to be used in the energy storage system is determined. The operation management device according to claim 1.

4. The aforementioned processing unit, Among the individual SOCs of the multiple energy storage elements, the minimum SOC representing the lowest value, the maximum SOC representing the highest value, and the average SOC representing the average value are calculated as the aggregated SOC. In the high SOC region, where the SOC is higher than the first set value, the first operational SOC is determined so that, as charging progresses, it approaches the maximum SOC from the average SOC. The operation management device according to claim 3.

5. The aforementioned processing unit, Among the individual SOCs of the multiple energy storage elements, the minimum SOC representing the lowest value, the maximum SOC representing the highest value, and the average SOC representing the average value are calculated as the aggregated SOC. In the low SOC region, where the SOC is lower than the second setpoint, the first operational SOC is determined so that, as discharge progresses, it approaches the minimum SOC from the average SOC. The operation management device according to claim 3.

6. The aforementioned processing unit, Among the individual SOCs of the multiple energy storage elements, the minimum SOC representing the lowest value, the maximum SOC representing the highest value, and the average SOC representing the average value are calculated as the aggregated SOC. In the intermediate SOC region, where the SOC is lower than the first setpoint and higher than the second setpoint, the operational SOC is determined to be equal to the average SOC. The operation management device according to claim 3.

7. The aforementioned energy storage system is a system for storing electricity that is bought and sold in the electricity market. The operation management device according to claim 1.

8. The first operational SOC, which is based on the integrated current value of the energy storage elements installed in the energy storage system, is converted to a second operational SOC, which is based on the amount of energy. Output the value of the second operational SOC after conversion. An operational management method in which processing is performed by a computer.

9. The first operational SOC, which is based on the integrated current value of the energy storage elements installed in the energy storage system, is converted to a second operational SOC, which is based on the amount of energy. Output the value of the second operational SOC after conversion. A computer program that causes a computer to perform a process.

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